Journal of Cleaner Production 279 (2021) 123676
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Journal of Cleaner Production
journal homepage: www.elsevier.com/locate/jclepro
Review
A review on the deteriorating situation of smog and its preventive
measures in Pakistan
Waseem Raza a, Saad Saeed b, Hammad Saulat a, Hajera Gul c, Muhammad Sarfraz a,
Christian Sonne d, Z.-H. Sohn e, Richard J.C. Brown f, Ki-Hyun Kim g, *
a
State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, 116024, PR China
NFC Institute of Engineering & Technology, Department of Chemical Engineering, Khanewal Road Opposite Pak Arab Fertilizers, Multan, 60000, Pakistan
National Centre of Excellence in Physical Chemistry, University of Peshawar, 25120, Peshawar, Pakistan
d
Aarhus University, Department of Bioscience, Arctic Research Centre (ARC), Frederiksborgvej 399, PO Box 358, DK-4000, Roskilde, Denmark
e
Department of Environmental Engineering, Dong-Eui University, Busan, 47340, Republic of Korea
f
Environment Department, National Physical Laboratory, Teddington, TW11 0LW, UK
g
Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul, 04763, Republic of Korea
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 2 May 2020
Received in revised form
1 August 2020
Accepted 9 August 2020
Available online 15 August 2020
Urbanization, industrialization, and increasing fossil fuel consumption are generally identified as the
main contributors to poor air quality. Smog is a form of visible air pollution processes that can cause
diverse health problems (e.g., pulmonary, respiratory, and skin diseases). In Lahore, the second-largest
city of Pakistan, smog pollution has been a significant socioeconomic issue since 2013 of which situation has been worsening each year. In this systematic review, we discuss the major issues concerning
smog in Pakistan: the causes, methods of detection, hazardous effects, and opportunities for preventive
measures based on ground-level information. This study identifies smog as a potential source of human
health risk as serious repercussions of economic development. It is thus suggested that adequate
abatement measures should be established for the proper protection of public health.
© 2020 Elsevier Ltd. All rights reserved.
Handling editor: Prof. Jiri Jaromir Klemes
Keywords:
Smog
Air pollution
Air quality
Smog prevention
Smog formation
Contents
1.
2.
3.
4.
5.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Types of smog and the related chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.1.
Classical smog (London smog) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2.
Photochemical smog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3.
Polish smog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Sources of smog in Pakistan and methods of detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Hazards of smog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1.
Effects on human health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2.
Effect on agricultural sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.3.
Effect on the economy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.4.
Effects on tourism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Smog preventive measures for Pakistan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1.
Technical measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1.1.
Transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1.2.
Domestic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
* Corresponding author.
E-mail address: kkim61@hanyang.ac.kr (K.-H. Kim).
https://doi.org/10.1016/j.jclepro.2020.123676
0959-6526/© 2020 Elsevier Ltd. All rights reserved.
2
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
5.1.3.
Industrial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Basic measures to improve air quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.2.1.
Increasing plantation area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.2.2.
Healthy practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.3.
Administrative measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.3.1.
Public awareness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.3.2.
Social & behavioral changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Funding source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Declaration of competing interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.2.
6.
1. Introduction
The adverse effects of air pollution on human health and the
environment, due to the myriad of pollutants released and
dispersed into the atmosphere, have been reported to be significant
worldwide (Kim et al., 2015b). Among these pollutants, fine particulate matter (PM2.5: particles less than 2.5 mm in diameter) is of
major environmental concern. The extremely small particle(s) can
travel into the human respiratory tract and penetrate the deep lung
epithelia, causing coughing, sneezing, shortness of breath, and
respiratory infections (Garçon et al., 2006; Grantz et al., 2003;
Raaschou-Nielsen et al., 2016). The main components of PM include
inorganic ammonium salts, nitrates, sulfates, sodium chloride,
mineral dust, black carbon, organic matter, and water (Pui et al.,
2014; Tucker, 2000). The primary sources of PM2.5 are agricultural
activities, road dust, vehicle emissions, power generation, general
combustion, construction sites, mining operations, and other
similar industries (Matus et al., 2012). It has been estimated that,
across the world, approximately two million deaths are caused
annually by air pollution of which nearly 25% are associated with
fine PM (Shah et al., 2013).
The word “smog” is a portmanteau of the words smoke and fog.
Fog is a visible aerosol consisting of tiny water droplets or ice
crystals suspended in the air; it can be considered as a low-lying
cloud. The distribution and properties of smog are shaped by
diverse factors including wind, temperature, and sunlight (Ali et al.,
2019b). Typically, smog is formed by chemical reactions when
excessive levels of key pollutants in the air (e.g., volatile organic
compounds (VOCs) and nitrogen oxides (NOx)) interact with oxidants (e.g., hydroxyl, ozone, and nitrates) (Fig. 1) (Arif, 2016; Liu,
2016). The main sources of the particles and pollutants needed
for smog formation include coal-fired power plants, traffic emissions, stubble burning, and erupting volcanoes (Kim et al., 2015b).
These activities can directly or indirectly contribute to the production of PM2.5 which is the main precursor for smog (Wang et al.,
2016b). Globally, the occurrences of smog have been reported fairly
frequently in many major cities around the world (e.g., Beijing,
Delhi, Lahore, Mexico City, Los Angeles, and Tehran) (Chen et al.,
2013; Mohammadi et al., 2012; Shabbir et al., 2019). The environmental significance of smog has started to attract attention since
the 1950s, with the report of well-known air pollution events in
London, UK. To tackle the smog problem, Clean Air Acts were
enacted by the UK and US governments, with the aim of mitigating
air pollution including smog (Longhurst et al., 2016; Thackeray,
2003). The concerns posed by smog on health and the environment have grown rapidly as evidenced by a large number of
research papers on the related issues (Fig. 2).
Air pollution has been one of the Pakistan’s main environmental
concerns in recent years. The situation has been worsening in
Lahore, the provincial capital. Lahore has a 4% annual economic
growth rate and is the second-largest city in the country (Riaz and
Hamid, 2018). In the latest air quality index (AQI) rankings of the
most polluted cities in the world, Lahore ranked the sixth, while
Karachi, the largest city in Pakistan, was the 16th with their AQI
values of 170 and 155, respectively (2019a).
The ranking of air quality between cities based on annual
average concentrations of PM2.5 (in 2018) is illustrated in Fig. 3
World most polluted cities (2018). Recent reports by Amnesty International and WHO have emphasized the need for immediate and
stringent abatement measures to mitigate smog events with the aid
of comprehensive air quality legislation (Ali, 2019; CarmonaCabezas et al., 2020; Organization, 2007). However, the emphasis
on creating public awareness as a preventive tool for smog can also
be a helpful option to implement such strategy. However, the
effectiveness of such approach is not likely significant, especially in
developing countries like Pakistan. The main factors contributing to
the increasing occurrences of smog in the developing countries are
generally identified to be the anthropogenic emission activities.
Therefore, an organized effort must be made to make the masses
learn more about the harmful effects of smog on the human health
and environment as well as the implementation of preventive
measures. Moreover, there are limited studies on the harmful effects of smog on human health in Pakistan with hardly any efforts to
assess its economic impact. The acquisition of the local data is also
necessary to support such mitigation efforts, which should be
instrumental in accelerating public response.
Although the government of Pakistan is making efforts to tackle
smog, further actions are needed to fully resolve this problem. In
this paper, we present a detailed analysis of smog, with respect to
causes, detection methods, impacts, and socio-environmental effects. Further, this review addresses preventive measures and the
steps required to resolve the smog-related problems in Pakistan.
Finally, we propose short- and long-term measures that may help
regulatory authorities establish proper mitigation measures to
control the smog issue.
2. Types of smog and the related chemistry
The chemistry of smog is complex and cannot be defined exactly
because of variability in its composition, both temporally and
spatially. However, it is conventionally categorized into two types:
classical (or London type) smog and photochemical (or Los Angeles
(LA) type) smog. Both are serious concerns in terms of their detrimental effects on the environment and human health. In addition
to these types, there is another distinct type of smog, identified
more recently, named Polish smog. In this section, we illustrate the
chemistry involved in formation of these types of smog.
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
3
Fig. 1. Schematic of smog formation in Pakistan.
2.1. Classical smog (London smog)
Classical, or London, smog is a lethal form of environmental
pollution. In December 1952, such a smog formed in London for
approximately 5 days, resulting in several thousand deaths
(Poulopoulos, 2016). This classical smog is also called sulfurous
smog, because it results from abnormally high concentrations of
sulfur oxides (1340 ppb in 1952) predominantly from burning of
fossil fuels, especially coal (Brimblecombe, 2017). The London Smog
was triggered by accumulation of excessive amounts of PM in the
air. In classical smog, the size of the PM increases due to high humidity levels; these particles then act as nuclei for formation of fog
droplets (Noone et al., 1992). Subsequently, sulfur dioxide dissolves
in the fog droplets and is oxidized to sulfuric acid, forming acid rain.
The major reactions are:
Fig. 2. Annual publications on smog in the last decade (data from Web of Science).
SO2 þ OH. / HOSO2
Fig. 3. 10 subcontinent cities recording highest PM2.5 concentration according to 2018 data (2018b).
4
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
HOSO2 þ O2 / HO2 þ SO3
R. þ O2 / RO2
SO3 þ H2O / H2SO4
From this series of reactions, it is clear that higher concentrations of VOCs may result in a lethal form of smog that affects air
quality by producing airborne particles and ground-level ozone. It
is also clear that photochemical smog depends on primary as well
as secondary pollutants.
Due to rapid industrialization and increasing energy and
transport demands worldwide, the atmospheric concentrations of
VOCs and other organic pollutants are increasing. Thus, photochemical smog has become a common environmental issue in
many cities of developing and developed countries worldwide,
forcing governments to develop mitigation strategies.
In 2016, Wang et al. (Wang et al., 2016) presented an experimental study to demonstrate the chemistry of London smog. It was
concluded that formation of classical smog was similar to oxidation
(in clouds) of SO2 by NO2. The main requirements for classical smog
generation are: (1) primary precursors including soot particles and
sulfur oxides, (2) secondary precursors including aerosols, (3)
inversion of radiation temperature, (4) high relative humidity, and
(5) low temperature. After the first lethal London smog event,
environmental agencies and governments implemented Clean Air
Acts worldwide, such as the Act imposed by the British government
in 1956 (the UK Clean Air Act) (Longhurst et al., 2016). However, this
type of smog still occurs in developing countries because of their
dependence on fossil fuels and the absence of stringent clean air
legislation.
2.2. Photochemical smog
Photochemical or Los Angeles (LA) smog is another type of air
pollution and is commonly observed in highly trafficked areas. The
presence of chemical species in urban air, with sunlight and other
specific metrological conditions, is responsible for creation of this
type of smog (Rani et al., 2011; Wang et al., 2014). Mainly, photochemical smog is composed of high concentrations of various
pollutants including oxides of nitrogen, ozone, carbon monoxide,
and aldehydes (Hu et al., 2011). During ozone formation in air, nitrogen dioxide from automobiles and industrial factories is photocatalyzed by solar radiation to generate nitrogen oxide and free,
unpaired oxygen. This unpaired oxygen produces further ozone by
reacting with oxygen radicals. Under normal conditions, the cycle
continues and produces nitrogen dioxide. However, in the presence
of volatile organic compounds (VOCs), the reaction mechanism
may lead instead to lethal photochemical smog. The chemistry of
photochemical smog has been described as follows (Wallace and
Hobbs, 2006):
(1) Decomposition of nitrogen dioxide by ultraviolet radiation
NO2 þ hn / NO þ O.
(2) Formation of ozone
O. þ O2 / O3
(3) Recycling to nitrogen dioxide
O3 þ NO / O2 þ NO2
(4) Production of reactive VOC molecules via reaction with hydroxyl radicals
RH þ OH. / R. þ H2O
(5) Formation of oxidized VOCs
2.3. Polish smog
In Europe, between 2015 and 2016, Poland was one of the most
polluted countries in terms of air quality index. In fact, 33 cities
from Poland were in the top 50 most polluted cities of Europe
(Dzikuc, 2015; Wȩdzik et al., 2017). This has posed serious threats
to European citizens, shortening their life expectancy, on average,
ska et al., 2019) identified a
by 9 months. Czerwinska et al. (Czerwin
new type of smog, naming it ‘Polish smog,’ that was different in
terms of chemistry from previously characterized smog types. This
type of smog was formed even at high atmospheric pressures and
low temperatures, different from London smog that occurs at low
atmospheric pressures (Bell et al., 2004). The main cause of Polish
smog is household boilers that release high concentrations of PM10
and PM2.5, as well as other carcinogenic compounds such as benzo
ski, 2019; Kryzia and Pepłowska, 2019). The specific
[a]pyrene (Kicin
feature of Polish smog is that it contains high concentrations of
PM10 under high atmospheric pressure and low temperature. Every
year, up to 48 thousand Polish people die prematurely due to Polish
smog (Malchrowicz-Mosko et al., 2019). This type of smog is not
limited to Poland; its effects are being observed in other European
countries with metrological conditions and pollutant emissions
profiles similar to those of Poland (Pastuszka et al., 2010). Thus,
more research needs to be performed by scientists in other parts of
the world concerning this new type of smog.
In Pakistan, it is difficult to determine the exact composition of
smog, as many factors are involved. However, the chemical
composition of the smog in Pakistan is similar to the other types of
smog (Tabinda et al., 2019). In the next section, we briefly discuss
potential sources of pollutants causing smog in Pakistan.
3. Sources of smog in Pakistan and methods of detection
Like many other developing countries, several emissions sources
(such as automobile exhaust gases, industrial sector pollutants,
disposal, use, and burning of solid waste, and agriculture activities)
detrimentally affect the air quality in Pakistan. Over the last two
decades, the usage of motorcars, scooters, and motorcycles has
increased with the increase in population, and the more than 10
million vehicles used by Pakistan’s population make a significant
contribution to air pollution (Maryam, 2018). From 1991 to 2012, a
remarkable increase in vehicles has been observed (450% for motor
cars, and 650% for motorcycles) in Pakistan (Maryam, 2018). Based
on the assessment on the formation of air pollutants (ozone) by
photochemical reactions in the Quetta region of Pakistan, it was
suggested that automobile exhaust should be a dominant driver in
the process (Ali et al., 2019a).
Many industries in Pakistan, such as steel mills, power plants,
and factories are sources of air pollution due to their use of furnace
oil (a major source of sulfur). In addition to these smog sources,
burning of crop waste is also a key contributor to smog formation in
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
various cities of Pakistan. More than 50,000 tons per day of solid
waste is produced in Pakistan, and is often incinerated. The incineration process releases toxic gas emissions (CO, SOx, and NOx) and
PM into the atmosphere (Maryam, 2018). Further, excessive
amounts of tropospheric O3 in the presence of aldehydes and ketones results in a peroxylacyl nitrate (PAN) photochemical smog
that can negatively affect human health (Usman et al., 2019).
Additionally, civil construction sector is also a major source that
results in environmental pollution. For example, emission of
pollutant gases can occur in the production of construction materials such as cement and hydrated lime (Marvila et al., 2019).
Cigarette waste has received less attention but it contains very toxic
and hazardous components (e.g., Pb, Cd, As, and Cr) (Girondi et al.).
In addition, a huge amount of food wastes is produced by restaurants (de Azevedo et al., 2020). Decomposition of organic materials
in the waste results in generation of biogas (e.g., large quantities of
methane and carbon dioxide with little amounts of hydrogen sulfide and ammonia). Thus, the decomposition of these organic
wastes in open air rather than at a proper place can result in suffocation and environmental pollution problems. Several methods
have been successfully designed and applied for early detection of
such pollutants. Various smog monitors, such as the AQS-1 smog
monitor (for photochemical smog), are available commercially and
can easily measure the severity of smog events and their corresponding constituents (including ozone, PM2.5, and VOCs)
(Emetere, 2019). The Punjabi government has purchased 6 air
quality monitors for Lahore for use during smog events, and
increased monitoring capacity is expected soon (Zahra-Malik,
2017). However, this monitoring system is not sufficient to cover
5
all smog events occurring in Pakistan. For this purpose, many
environmental activists are working in various cities (Lahore,
Islamabad, and Peshawar) in Pakistan to provide accurate data on
smog events (Hashim, 2020). The methods of detection for various
primary and secondary pollutants that may cause smog are summarized in Table 1. This review was organized to cover mainly the
sources reported to be associated with emissions of smog or major
smog components rather than the common sources of air pollution
in general. To the best of the authors’ knowledge, all the credible
and relevant studies reporting statistical data on the subject of this
review have been presented. In addition, the preventive measures
are proposed based on the demography of Pakistan, which can also
be applied to the whole sub-continent.
4. Hazards of smog
Smog is a mixture of many pollutants, chiefly particulate matter
(mostly PM2.5), but also sulfur dioxide (SOx), nitrogen oxides (NOx),
carbon monoxide (CO), volatile organic compounds (VOCs), ozone
(O3), peroxylacyl nitrates (PAN) and aldehydes. Each component is
harmful to humans, plants, animals, and the natural environment,
especially in high concentrations. Recently, Butt et al. (2018) summarized various human health effects (asthma, diabetes, headache,
and others) arising from smog events in Lahore. However, that
study was limited to medical students. The general detrimental
effects of smog constituents and their acceptable concentration
limits for protection of human health are briefly described in
Table 2.
Table 1
Common monitoring methods for smog components.
Primary pollutants
Order Pollutant
Monitoring Description
method
1
NOx
2
VOC
Triethanolamine (TEA)- or sodium iodide/sodium hydroxide-impregnated filter
(Sluis et al., 2010; Villena et al., 2011)
Calorimetric dosimeter with impregnated paper
Integrated Saltzman impinger or bubblers with calorimetric detection using a mixture of Nethylenediamine dihydrochloride, sulfanilic acid, and acetic acid.
Sampling with front filter followed by TEA-impregnated cellulose-fiber filters for
ion chromatography (IC) analysis of nitrite.
Continuous Chemiluminescence
Electrochemical sensor
Photoacoustic spectroscopy
Long-path absorption photometer
ski, 2019; Lan et al.,
Passive
Activated charcoal, tenax, or other thermally desorbed sorbent, followed by GC-MS (Ge˛ bicki and Szulczyn
Polyurethane foam (PUF) or XAD resins with samples extracted in organic solvents 2020)
before chemical analysis.
Integrated Canister, bag, or carbotrap sampling mainly for hydrocarbons
Filter/PUF or filter/tenax for polycyclic aromatic hydrocarbons (PAH) mainly.
Filter impregnated with dinitrophenylhydrazine (DNPH) or cryogenic traps for
carbonyls
Quartz-fiber filters or base-coated filters
Continuous HCs by automated GC-FID
Proton-transfer-reaction (PTR)-MS
Chemical Ionization Mass Spectrometry (CIMS)
Passive
Secondary pollutants
1
O3
Passive
2
3
Ref.
(Bogue, 2008; Carmichael et al., 2003; Ferm
Impregnated nitrile or nitrate followed by IC analysis
and Svanberg, 1998; Zi-wei et al., 2002)
Treated strips that react with O3 followed by color scale comparison
Potassium iodide (KI)-impregnated filter
Integrated
Sampling with front filter followed by KI-impregnated cellulose fiber filters for
automated calorimetric analysis of KOH.
Continuous Chemiluminescence
UV absorption
Continuous Chemical Ionization Mass Spectrometry (CIMS)
Eger et al. (2019)
Peroxylacyl
nitrates (PAN)
Aldehydes
Integrated
Dinitrophenylhydrazine (DNPH)-coated substrate to form hydrazones followed by Poli et al. (2010)
HPLC analysis
Palmes-type tube coated with sodium bisulfite (NaHSO3)
Continuous Automatic GC-FID
6
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
4.1. Effects on human health
Smog has severe adverse effects on human health. There is evidence to support the claim for acute detrimental effects on cardiovascular and respiratory systems (Gurmeet Singh, 2020). The
severity of smog hazards depends upon the quantity inhaled, the
components present, and the individual characteristics (e.g.,
weight, age, and well-being) (Fuzzi et al., 2015). In the year 2005,
PM2.5 and O3, the main components of smog, resulted in the deaths
of nearly three million people globally due to respiratory diseases,
lung cancer, and cardiovascular diseases (Lelieveld et al., 2013). The
intensity of the effects on human health due to smog exposure is
shown in Fig. 4. As the major component of smog, PM in any form is
a well-recognized cause of early mortality. However, the size of the
PM is directly linked to the severity of the health issues it causes.
There is a considerable risk of a smaller particles penetrating
deeper into the respiratory system and settling on the respiratory
tract, more extensively damaging the lungs and the whole respi€ndahl et al., 2006).
ratory system (Lo
A strong link between adult diabetes and PM concentration in
air was also reported in a US epidemiologic study (Han, 2019). Since
children are less immune to infections than adults, if they experience long-term exposure to the high levels of PM present in smog,
they have a higher risk of respiratory infections. Several studies
conducted in the US (Ritz et al., 2000), China (Fleischer et al., 2014),
Pakistan, and Canada (Brauer et al., 2008) have found that high
exposure to PM2.5 in smog is one of the major causes of intrauterine
inflammation leading to preterm birth. Preterm birth, in the short
run, causes many post-natal deaths and, in the long run, significantly reduces life expectancy. Malley et al. (2017) reported the
preterm birth data from 183 countries and found that up to 18% of
preterm birth cases occur due to high PM2.5 exposure. The highest
percentages occurred in South and East Asia, North Africa, the
Middle East and West Sub-Saharan Africa.
Ozone, another chief component of smog, is highly reactive and
poses serious health risks. Like PM, ozone also attacks the cardiovascular and respiratory systems after oral and nasal absorption,
with children and women being most vulnerable and susceptible
(Naveed, 2016). Secondary oxidation products (such as PAN)
formed by reaction of ozone with components of epithelial lining
fluid (ELF) can cause cell and tissue damage (Nuvolone et al., 2018).
Studies have revealed that an increment of 10 mg m3 of ozone
increases the risk of mortality by 0.26% (Jia et al., 2011).
With PM levels in Lahore nine time higher than the WHO limits,
significant health effects from smog pollution are expected. According to air quality figures reported by an independent body, the
Pakistan Air Quality Initiative (PAQI), from 1 January to 31
December 2017, all the cities considered (Lahore, Peshawar,
Islamabad, and Karachi) were above the 10 mg/m3 international air
quality limit recommended by WHO (with PM2.5 levels of 130, 63,
42, and 40 mg/m3, respectively) (Omar, 2018). The city of Lahore
recorded the poorest air quality, reaching the ‘very unhealthy and
hazardous’ level 28 times in the year 2017 (see Fig. 5). Ashraf et al.
(2019b) analyzed the relationship between smog and ocular surface
diseases in patients in tertiary care hospitals in November 2016.
Samples for smog analysis were collected during and before the
smog event (which occurred in November 2016) from three busy
locations in the city of Lahore, namely Mall Road, Gulberg, and
Township. Sheikh Zaid and Mayo Hospitals were randomly chosen
for collection of data on ocular surface diseases from 2e5
November 2016 using a random clustered sampling technique. The
distribution of smog pollutants at the three locations is given in
Fig. 6 (as per the United States Environmental Protection Agency
measurement protocol) (EPA, 2019). Among the smog components,
the highest concentration was for NOx, which had a value 17 times
higher than the corresponding value in the same month of 2015.
The other smog components also exhibited a significant increase;
this is likely to be further exacerbating health issues. In comparison
Table 2
Adverse effects of smog components on human health.
Order Components Permissible limits
of smog
(WHO guidelines)
Main sources
Adverse effects on human health
1
PM2.5
Annual
mean ¼ 10 mgm3
24-h
mean ¼ 25 mgm3
2
Ozone
8-h
mean ¼ 100 mgm3
3
CO
8-h
mean ¼ 10 mgm3
15-min
mean ¼ 100 mgm3
4
NOx
Annual
mean ¼ 40 mgm3
1-h
mean ¼ 200 mgm3
5
SOx
24-h
mean ¼ 20 mgm3
10-min
mean ¼ 500 mgm3
PM2.5 has been identified as one of the main sources of air pollution,
Power plants, forest fires, motor vehicles,
airplanes, crop burning, volcanic eruptions, with wide-ranging adverse effects on human health. Although PM2.5
dust storms.
is harmful even in small amounts, prolonged exposure to high levels
can lead to severe cardiovascular and respiratory diseases, asthma,
arrhythmia, and damage to the central nervous system. A decrease of
10 mg m3 of PM2.5 could increase life expectancy by 0.35 years on
average.
Photochemical reaction of sunlight with NOx Ozone (O3) is harmful to the cardiovascular, respiratory,
and VOCs emitted from motor vehicles,
reproduction, and central nervous systems. Common health hazards
power plants, brick kilns.
include shortness of breath, wheezing, coughing, nasal
hyperresponsiveness, chronic obstructive pulmonary disease,
asthma, malfunctioning of the immune system.
Motor vehicles, chemical processing plants, CO can be deadly in high concentrations. It hampers the ability of
volcanoes, bushfires.
hemoglobin to carry oxygen to the lungs, thereby depriving vital
tissues of oxygen. High exposure can prove fatal for infants, elderly
people, and people with anemia, cardiovascular diseases, or
respiratory problems. Headache, vomiting, dizziness, and nausea are
common effects of CO exposure. Prolonged exposure to high-level CO
may result in death.
NOx gases react to form acid rain, smog, PM2.5, PM10, and ozone. In
Motor vehicles, construction equipment,
power plants, cement kilns, industrial
high concentrations, NOx can penetrate deep into the respiratory
boilers.
system, aggravating emphysema or bronchitis, even resulting in
mortality in extreme cases. NOx can also react with other chemicals
to produce toxic products such as nitrosamines and nitroarenes,
which can cause DNA mutations.
Fossil fuel burning plants, motor vehicles,
Sulfur dioxide can travel deep into the lungs through the nasal
volcanic eruptions.
passage, react with water, and form sulfuric acid, which is damaging
to the digestive system and is a precursor to acid rain and particulate
matter. Exposure to high concentrations of sulfur dioxide can
severely damage the respiratory system, even leading to death.
Ref.
Kim et al.
(2015a)
Salonen
et al.
(2018)
Flachsbart
(1999)
Quansah
et al.
(2017)
Lee et al.
(2018)
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
7
Fig. 4. Hierarchy of the effects of smog on health.
Fig. 5. Air quality status of four major cities of Pakistan in 2017, presented as a proportion of the number of days in that year with a certain air quality classification (Ullah and
Zeshan, 2019).
with the previous year, 2015, the AQI was six times higher. The
hospital data revealed that the number of patients suffering from
ocular related diseases had more than doubled, from 2000 in
2015e5000 in 2016 (Ashraf et al., 2019b). The most common
detrimental effects were irritation, lid erosion, corneal diseases, dry
eyes, uveitis, and lacrimation (making up approximately 20, 4, 7, 12,
3, and 11% of cases, respectively.)
4.2. Effect on agricultural sector
In addition to human health, smog has devastating effects on
plants and animals. Smog hinders plant and tree growth indirectly
by blocking the rays of the sun and directly damages crops and
vegetables. Crops such as wheat, tomatoes, soybean, cotton, and
peanuts were reported to suffer from infections and lose immunity
to disease due to smog exposure (Gheorghe and Ion, 2011). The
debilitating effects of smog on the ecosystem include biodiversity
reduction, low primary and secondary production, and decreased
resistance to disease. The inert pollutant particles cause only
physical damage to vegetation, whereas the toxic chemical particles
cause both physical and chemical damage (F. L. Farmer, 1993). In
fact, the penetration of harmful smog components into the soil is
more deleterious than direct deposition at the plant surface
(Seyyednejad et al., 2011). Surface deposition of smog pollutants
(PM deposited on leaves and other plant surfaces) curtails photosynthesis, inducing premature leaf fall and permanently damaging
leaf tissues. Likewise, smog adversely affects the microorganisms
that live on plants and trees, which may also inhibit the decomposition process after litter fall (Graiver et al., 2003). Studies have
revealed that dust particles from brick kilns (a key source of
8
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
Fig. 6. Concentrations of smog components measured at different monitoring stations
in Lahore, Pakistan (Ashraf et al., 2019a).
pollution in Pakistan) can raise the alkalinity of plant leaves to as
high as pH 12, which can distort proteins and dehydrate plants in a
process known as plasmolysis (Shi et al., 2000).
Smog adversely effects Pakistan’s export of crops (cotton, wheat,
rice etc.). Recent studies on the effect of smog, particularly PM and
ozone, on crops in Pakistan have revealed a significant drop in
yields (Khan, 2013). Wahid et al. (1995a) researched the effect of
smog pollutants on two cultivars of winter wheat. The findings
revealed a 34.8e46.7% decrease in wheat yield, chiefly as a result of
ozone. In a similar study on three varieties of wheat, significant
reduction in stomatal conductance, transpiration rate, and photosynthetic efficiency was observed as a result of exposure to smog
components, primarily ozone. Another vital crop, barley, also
experienced a substantial decrease in seed yield (13e44%) when
exposed to smog components such as NOx, SOx, and ozone (Wahid,
2006). A similar study on rice by the same researchers revealed a
37e42% reduction in the yield of two cultivars of local rice crops
(Wahid et al., 1995b). A study on the impact of brick kiln emissions,
a major cause of smog formation, on wheat production in Faisalabad, a city in Punjab province of Pakistan, showed a loss in grain
yield, decrease in plant height and photosynthetic activity, and the
presence of metal in the crops as a result of exposure to such
emissions (2019b). Such a significant reduction in crop yield, for a
developing and agriculture-dependent country, is a matter of great
concern. With increasing demands on agriculture due to the evergrowing population, there is a need to reduce the negative effects
of air pollution to optimize food production.
4.3. Effect on the economy
Air quality and the economic progress of a country are intertwined. The economy thrives on healthy people, active businesses,
flourishing tourism, and increasing employment. Air pollution,
especially smog, hampers all these activities and consequently
slows the economy. The accumulation of smog in the morning
hours to the afternoon negatively affects productivity during the
working day. Recently, due to heavy smog, public and private
schools remained closed for several days in Schools in Lahore
(2019). The economic corridor between China and Pakistan (62
billion USD investment), one of biggest economic projects in Asia, is
also facing serious challenges due to the effect of smog in disrupting transportation routes in the vicinity of the corridor (Kouser
and Subhan, 2020; Raja et al., 2018). It is claimed that the GDP of
Pakistan (47.8 USD billion) will be decreased by more than 5.88% if
smog is not properly controlled. The devastating effects of smog on
human health (11 million people complained of eye irritation and
headaches) and the agricultural sector in Pakistan may translate
into an economic slowdown (Sarfraz, 2020).
The premature mortality and long-term illnesses of working
men and women resulting from smog pollution can also cause
economic losses, including reduction in family income. According
to the World Bank report in 2016, air pollution caused a 5 trillion
USD annual loss to the economy. Developing countries are most at
risk, with annual labor income losses amounting to 1% of total GDP
in South Asia (World Bank, 2016). The total welfare costs due to air
pollution may be divided into four major components: direct
market costs, indirect costs, disutility, and mortality. In 2015, the
total worldwide welfare cost due to atmospheric air pollution
amounted to 3.8 trillion USD and is expected to rise to 24e31
trillion USD by 2060 (OECD, 2016) (see Fig. 7). Since the air pollution considered in this study was primarily PM2.5 and ozone, along
with the other smog components, these results could in large part
be justifiably attributed to smog. This suggests that stringent
abatement policies are urgently needed to avoid serious future
consequences.
4.4. Effects on tourism
Smog affects tourism in a country by causing severe damage to
visitor attractions such as historical buildings and monuments
(Peng and Xiao, 2018). Moreover, many tourists, for health reasons,
will avoid visiting a country notorious for high air pollution. One of
the main motivations for tourists to visit a country is to experience
the landscapes, rivers, mountains, and historical or state-of-the-art
buildings. However, smog negatively affects the tourist experience
by lowering visibility and decreasing the aesthetic beauty of the
scenery. The reduction in visibility caused by smog multiplies the
risk of road accidents. For example, 10 people were killed and
several were injured in November 2017, due to impaired visibility
caused by smog (Shabbir et al., 2019). Poudyal et al. (2013) used
econometric models to determine the correlation between visibility and number of tourists and found that a 10% increase in visibility
could bring in an additional one million visitors to a park.
Pakistan is a country rich in historic locations and destinations
of archaeological interest. It has a growing tourism industry and has
the potential of becoming a very popular global tourist destination
(Fig. 8) (Manzoor and Wei, 2018; World Asia, 2018). However,
smog-related air pollution in the mega cities such as Lahore and
Peshawar has caused serious concern, not only to the local public,
but also to international visitors, such as members of the Sikh
community, who visit their holy shrine in Katarpur (Khan, 2013;
Khilji, 2019). Hence, to sustain a growing tourism industry in
Pakistan, it is imperative to mitigate smog-related sources of air
pollution.
5. Smog preventive measures for Pakistan
For all types of smog, the precursors come primarily from
anthropogenic emissions. Thus, proper mitigation of these emissions is required to abate smog effectively. Many strategies have
been developed, on a local, regional, and even international scale
(Shi et al., 2016). However, prevention of smog (to improve air
quality indices for a given area) is rarely dependent on a single
intervention but, instead, generally depends on various abatement
measures working in concert. These interventions may be regulatory, economic, social, or technical in nature (see Fig. 9) (Shi et al.,
2014). All the activities shown in Fig. 9 can be applied separately
to mitigate smog formation and its corresponding hazards, but they
are most effective when combined. In this section, we provide a
detailed discussion on various prospective preventive measures
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
9
Fig. 7. Predicted 2060 shares of total welfare costs due to air pollution according to contributing component across a number of countries (OECD, 2016).
Fig. 8. Number of tourists visiting Pakistan annually in the last decade (Manzoor and Wei, 2018).
(technical, basic, and administrative) for the specific case of
Pakistan.
5.1. Technical measures
5.1.1. Transportation
Due to the rapid increase in population and growth in the
economy, Pakistan has seen increased use of transportation, which
has become a major driver of smog events. According to Xi et al.
(Xie et al., 2019), approximately half of all total emissions of volatile
components that ultimately affect air quality in the respective regions of world are produced by vehicles. In this respect, Pakistan is
facing serious challenges in the transportation sector, including
requirements to upgrade the vehicle fleet to cleaner models, and a
current lack of vehicle maintenance and monitoring legislation
(Shah and Arooj, 2019).
The increased use of private vehicles in Pakistan (Fig. 10) has
posed serious problems for air quality. Punjab province has
approximately 19.6 million vehicles, 6.2 million of which originate
in Lahore (zahid, 2020). Two-stroke engine vehicles, such as motorcycles, motorized rickshaws, and other three-wheel vehicles, are
a common mode of transportation in Lahore, and are among the
most polluting of all combustion engine vehicles. The huge number
of private vehicles on the road produces large amounts of gaseous
pollutant compounds, which are major precursors for production of
smog. In this context, the use of private cars must be reduced, and
use of public transport must be encouraged e possibly through the
use of "low emissions zones" such as are found in London (2020).
Song et al. (2016) suggested that development of a mass transit
railway system (using, for instance, high speed electric trains)
10
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
Fig. 9. Preventive measures to minimize emissions that produce smog and to reduce its detrimental effects.
in exhaust gases (Sassykova et al., 2019).
Recently, the automobile industry has promoted the hybrid
motor concept to increase the use of green energy (Prajapati et al.,
2014). Benajes et al. (2020) suggested that use of advanced combustion modes with plug-in hybrid electric vehicle technology can
reduce emissions of CO2, nitrogen oxides, and soot by 12e30%.
However, the operation and manufacturing cost of the technology,
as well as the long recharging time, should be taken into consideration since consumers are generally reluctant to switch their
vehicle choices until the new option becomes more user-friendly
than the existing technology (Millo et al., 2014).
Fig. 10. Total number of registered vehicles in four of Pakistan’s administrative divisions (2018a).
would have a significant effect in improving air quality. Strategic
policies for monitoring and controlling traffic congestion are
another preventive factor in reducing harmful emissions and,
therefore, smog formation. Secondly, it is vital to strengthen the
monitoring and emissions policies on new automobiles, reduce
direct emissions of vehicles per unit distance, and promote the use
of renewable energy vehicles and clean technologies to progressively reduce the possibility of smog events (Xie et al., 2019).
In the transport sector, vehicle maintenance and inspection on a
regular basic are other positive actions that may reduce detrimental
emissions. The condition of the engine is an important factor in
determining the extent of air pollutant emissions from a motor
vehicle. Thus, the engine should be tuned regularly, and the engine
case ventilating system, muffler, and fuel system should be
inspected on a consistent basis. The design of motors, as well as
their operating condition, fuel type, distance travelled, and amount
of work performed are additional important factors to consider
when determining how to reduce the amount of harmful pollutants
5.1.2. Domestic
At the domestic level, gas-powered equipment such as heaters,
stoves, generators, pumps, compressors, high pressure washers,
floor buffers, and high-pressure drills are the main sources of carbon emission, especially CO (Hanzlick, 2007). The solution to this
situation is to adopt technology that is powered by electricity or
compressed air, if these are available and can be used safely (Garcia
et al., 2007).
Smog increased in Pakistan as result of rapid industrialization
and domestic activities. Ali et al. (2019a) illustrated use of the fuzzy
VIKOR model to mitigate the effect of toxic smog on human health
by developing an appropriate environmental policy in Pakistan. The
results of the fuzzy VIKOR model illustrate that the effects of smog
can be minimized by reducing industrial waste and by educating
farmers and other communities on ways to lessen their emissions
and, therefore, their contribution to smog formation. Implementation of this model will help the government of Pakistan in
making future policies. Recently, Saeed and colleagues launched a
project to build a 25-foot solar powered smog-cleaning tower in
Pakistan. According to their claims, the project has the capacity to
provide smog-free, clean air for 90,000 residents in the vicinity
(HADID, 2020).
5.1.3. Industrial
As Pakistan is a developing economy, it does not always use
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
state-of-the-art abatement technology in its industrial processes.
The manufacture of bricks is usually achieved by chimney-based
brick kilns fueled by wood, crop residue, and coal (Sarfraz, 2020;
Shabbir et al., 2019). Approximately 20,000 brick kilns are operational across the country; most of the kilns are located near urban
areas. Emissions from these facilities can cause severe environmental problems in the cities of Pakistan (Khan et al., 2019; Mondal
et al., 2017). There is a need for the brick industry in Pakistan to
abate emissions to avoid smog events. Treatment of smoke with
wet or dry filters, use of purifiers, and use of modern artisanal brick
kilns are solutions to this problem. Air pollution control equipment
(with baffle arrangements inside chimneys), along with gas bypass
systems, can also help to mitigate pollution. Mechanical feeders
and cleaner technologies, such as vertical shaft kilns, can also be
effective because they ensure the most efficient burning of coal,
which lowers emissions (Skinder et al., 2014). Replacement of
conventional fossil fuels with renewable energy resources (such as
solid waste and biomass fuels) is being considered as a viable option for powering future industry in Pakistan, because it can reduce
the emission of methane and N2O from landfills (Herbert and
Krishnan, 2016).
Anthropogenic activities are another source of chemical pollution and can be transported long distances, affecting the global
environment (Himawan and Sari, 2018; MIRO et al., 2019). More
than 90% of all industrial emissions globally are from coal (far
exceeding the level of emissions from other anthropogenic sources
such as mercury mining, gold smelting, nonferrous smelting, iron
steel production, domestic wastes, and cement production) (Huang
et al., 2017). Emissions from industrial activities such as power
production are generally caused by combustion of solid fuels
(which are frequently a significant, yet unidentified source of the
precursors of smog in Pakistan and other developing countries).
Therefore, use of substitute industrial fuels such as oil and gas and
development of methods harnessing energy from renewable
sources would mitigate smog formation in Pakistan (Liu et al.,
2016).
5.2. Basic measures to improve air quality
5.2.1. Increasing plantation area
Currently, Lahore city faces its most severe air pollution problems between November to February each year, when a blanket of
toxic haze covers the entire city, as well as some districts of
Pakistan Khyber Pakhtunkhwa (KPK) (Jahan et al., 2019). Several
researchers have stressed the significance of plantation area to
control environmental pollution such as smog (Saxena, 2014; Zona
et al., 2014). In this respect, governments globally have initiated
new smog control policies through creation of woodlands in and
around major industrial cities to create a green barrier between
industrial and urban locations. The Pakistani government has also
launched the Billion Tree Tsunami Afforestation Project to
encourage planation (Kamal et al., 2019).
Plantation and forest growth help to control the microclimate,
protect inhabitants from heatwaves, and add oxygen to the atmosphere. Leung et al. (2011) reported that shade can reduce the
extreme smog concentration by 5%, which is equivalent to reducing
the smog precursor NOx by 175 tons/day (25 times more than the 4
tons/day improvement gained through reducing power plant
emissions). According to Professor Barry Lefer at University of
Houston, increasing plantation area is a good idea, but there is "no
assurance that the plants are cleaning up emissions where we need
the reductions. The timing and location of the plantation really
matters" because some plant types discharge biogenic volatile
organic compounds, potentially increasing ozone and particulate
matter to worsen air quality (Florence, 2004; Kegge and Pierik,
11
2010; Tresaugue). Furthermore, pollen grains and fungal spores
from plants are health risks for allergy-suffering or other sensitive
members of the population.
5.2.2. Healthy practices
Since vehicular emissions are a significant source of smog,
adopting basic smog preventive practices such as walking, biking,
and using public transport can have a significant positive outcome.
Another way is to move to eco-friendly consumer products, such as
paints, papers, plastics, and sprays that contain low levels of VOCs.
Laumbach et al. (2015) highlighted individual efforts to reduce
personal health risk caused by air pollution, such as smog events.
They suggested that limiting personal exposure by staying indoors,
filtering indoor air, and limiting physical exertion can play a key
role in protecting personal health during winter smog. The Provincial Disaster Management Authority (PDMA) of Pakistan has
issued guidelines on avoiding outdoor activities during smog
events, using masks, and using and cleaning indoor air filters
(PDMA, 2017).
5.3. Administrative measures
5.3.1. Public awareness
Public education and awareness of smog and its effects on human health and the environment are essential factors that cannot
be neglected when addressing these problems (Ahsan et al., 2020b;
Wang et al., 2016a). Recently, Saleem et al. (2019) conducted a
public survey about smog awareness and its preventive measures in
Punjab, Pakistan. The survey of a cross section of 607 selected individuals revealed that increasing public awareness (via social
seminars, conferences, and community campaigns) can play a key
role in mitigating smog-related air pollution. Thus, the public
should be educated more widely about the hazardous effects of
smog through public information sessions and preventive measures programs (Mehiriz and Gosselin, 2019). In a similar study,
Ahsan et al. (2020a) demonstrated that, for Lahore residents,
sociodemographic factors (particularly education level) can play a
key role in understanding smog hazards and smog mitigation
policies. Information sources such as online media content and
mobile apps should be used to warn the public about the severity of
air pollution, allowing them to mitigate short term health effects by
staying indoors and not exerting themselves (Li and Tilt, 2019).
5.3.2. Social & behavioral changes
Along with public awareness and engagement, trust in the information provided is also important. For example in 2013e2014,
China launched a nationwide program providing real-time air
quality assessment to the public (Barwick et al., 2019). This program
resulted in household behavioral changes, increased online
searches for pollution-related topics, adjustments in day-to-day
consumption patterns that reduced exposure to pollution, and
higher willingness to pay for housing in less polluted areas. As a
consequence of both short- and long-term behavioral changes, the
program resulted in reduced mortality due to air pollution by
nearly 7%. Estimates suggest annual benefits amounting to 18
billion USD from the program, a figure at least one order of
magnitude larger than the combined costs of the program and
associated avoidance behaviors (Ito and Zhang, 2020). Thus,
improved public awareness and associated promotion of social and
behavioral changes are recommended to help mitigate smog episodes and their effects in Pakistan. Considering the preventive
measures discussed in this section, we have proposed short- and
long-term policy instruments (Fig. 11) that may help regulatory
bodies in Pakistan mitigate smog problems.
12
W. Raza et al. / Journal of Cleaner Production 279 (2021) 123676
Fig. 11. Proposed short- and long-term policies to mitigate smog pollution in Pakistan.
6. Conclusion
Declaration of competing interest
Globally, many big cities such as Beijing, Delhi, Lahore, Mexico
City, Los Angeles, and Tehran are negatively affected by smog. Dependency on fossil fuels to support fast growing urbanization and
industrialization contributes significantly to smog events in
Pakistan. Vehicular emissions, along with burning of crop and solid
waste, are considered the major sources of smog in Pakistan. Smog
has harmful effects not only on human health, but also on animals,
tourism, and other parts of the economy. Lahore, the second biggest
city in Pakistan, is one of the worst affected by winter smog events.
In this study, we presented the sources of smog events, their hazards, and possible preventive measures to help abate smog in
Pakistan. Note that there are not many specific studies highlighting
the statistical impact of smog on the economy of Pakistan. Further,
smog preventive measures require stringent policies and emissions
abatement strategies to reduce the use of private cars, although
such efforts are yet insufficient on national basis. Increasing the use
of public transport must be encouraged by providing better facilities. Vehicle maintenance legislation should be improved and
enforced, and the benefits of hybrid vehicles should be widely
promoted. Industrial emissions from different sources should be
monitored, treated, and reduced by implementing green industrial
policies. Pakistan is using an effective green plantation strategy to
reduce the severity of smog events in mega cities. Irrespective of
government policies, the occurrence of smog events can also be
mitigated by community measures such as social seminars and
public education that promote behavioral changes. Thus, a combined effort by both government institutions and individual citizens of Pakistan is needed to reduce the occurrence of smog events.
The authors declare that they have no known competing
financial interests or personal relationships that could have
appeared to influence the work reported in this paper.
Funding source
A grant from the National Research Foundation of Korea (NRF)
funded by the Ministry of Science ICT and Future Planning (No.
2016R1E1A1A01940995).
Acknowledgements
KHK acknowledges the support made by a grant from the National Research Foundation of Korea (NRF) funded by the Ministry
of
Science
ICT
and
Future
Planning
(Grant
No:
2016R1E1A1A01940995).
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