AIR QUALITY NETWORKS IN SMART CITIES
1. Introduction
Clean air is considered to be a basic requirement to human health and well-being. However, air
pollution continues to pose a significant threat to health worldwide and is a critical environmental
issue that cannot be ignored. According to a WHO assessment about the burden of disease due to air
pollution, more than two million premature deaths each year can be attributed to the effects of air
pollution. More than half of this disease burden is from the populations of developing countries
(WHO, 2005).
The increasing trend of the global urbanization results in high levels of air pollutants in urban
areas and megacities, decreasing air quality. Transportation, road traffic, home heating, industrial
emissions, and other local anthropic actions are the major emission sources of air pollutants to the
atmosphere.
Air pollution control and air quality monitoring is needed to implement abatement strategies and
stimulate environmental awareness among citizens. For this purpose, there are several techniques and
technologies that can be used to monitor air pollution (Penza et al., 2014).
2. Air Quality Networks in Brazil
In developing and recently newly industrialized countries, studies on air pollution have started
later than in Europe and USA, but have also been showing negative effects on health, mainly in the
respiratory and cardiovascular systems (Olmo et al., 2011).
In Brazil, the National Environmental Council – CONAMA issued in 1989 the resolution No.
05/1989, determining the creation of a "National Network of Air Quality Monitoring" and it was also
created the National Program for Air Quality Control – PRONAR.
The first legal PRONARs device was the CONAMA resolution No. 03/1990, which establishes
the national air quality standards (CONAMA, 1990). However, air quality monitoring has not
constituted a routine activity in most of the Brazilian States (MMA et al., 2009), being confirmed by
IEMA (2014) that it occurs only in 12 States, among its 26 and the Federal District. This review
allowed the identification of 3 weaknesses, namely, the existence of highly heterogeneous networks;
frequent situations of activities discontinuance with interruptions in the air quality network operation
and low efficiency and reduced representability, not allowing the fulfilment of a suitable air quality
diagnosis.
As a way of overcoming the previous limitations, several priorities can be identified, explicitly,
extending the territorial coverage of air quality networks; defining and disseminating general criteria
for planning, implementing, operating and expanding networks; broadening technical capabilities,
allowing the restructuring and readjustment of networks for better data quality; and reorganizing the
national regulatory framework on air quality, allowing an answer to this need of restructuring and
expansion of air quality monitoring networks to emerge.
3. Air quality network in the area directly affected by TRANSFOR in Fortaleza
A well-known way that could improve air quality is to implement Bus Rapid Transit – BRT,
which are defined, according to the Institute of Transportation & Development Policy – ITDP, as an
innovative, high capacity, lower cost public transit solution that can significantly increase urban
mobility and reduce the number of vehicles with consequent decreasing in air pollutants. This system
is already implemented in 33 Brazilian cities and being planned in many others metropolitan areas.
In 2014 the Institute of Environment and Development – IDAD, in consortium with the
Laboratory Control of Air Pollution – LCPA of the Federal University of Rio de Janeiro, developed a
project that had as goal the design and operationalization of an air quality monitoring network, aimed
at monitoring the effects on air quality of the implementation of a BRT system, in the area directly
affected by the Urban Transport Program of Fortaleza – TRANSFOR in the city of Fortaleza, Brazil.
This project was financed through a IDB grant.
In order to identify the area directly affected by the TRANSFOR program regarding air quality, an
air pollution dispersion model was applied to the main traffic roads of the city, thus identifying
potential critical areas. With this information and air quality diagnosis the design of the air quality
monitoring network was made (IDAD and LCPA, 2014).
The air quality monitoring strategy proposed to Fortaleza is mainly based on measurements from
fixed monitoring stations that use equipment with standardized methods. Due to costs and equipment
size limitations, air quality monitorization with standard equipment are usually limited to a few
number of locations. However there are technologies of air quality monitoring, such as microsensors
that can be applied as a complementary application in this kind of projects and provide a different and
innovative approach, allowing larger spatial coverage.
4. Microsensors in air quality networks
The raise of awareness on air quality issues combined with the development of low-cost sensing
technologies allowed to look to complementary applications with potential for monitoring studies.
Therefore, the use of microsensor networks can be seen as innovative tools for future applications on
air quality monitoring. In this context, with the development of the Digital Era, the real-time collected
data can be used to have a more detailed space and time resolution profile of air quality data which
must be complemented with information from standard equipment, supporting decisions and
informing the general public.
Adopting low-cost methods for robust environmental surveillance can represent a solution to
overcome the lack of small geographical scale. Although these methods tend to produce lower quality
data, they are able to be used in a high number of locations simultaneously, which allows for highresolution exposure assessment mapping city environments. Data from microsensor networks could
provide more accurate input conditions leading to more robust and reliable conclusions about air
quality levels. The deployment of microsensors in significant numbers can also assist in conducting air
emission inventories and detecting pollution hotspots, as well as allowing real-time exposure
assessment for designing mitigation strategies. Retrieving data from the sensors is straightforward and
their automatic operation allows for wide-spread deployment in the built environment. The use of
sensors in this way provides granularity, which better informs the identification of pollution sources
and helps support more conclusive studies on the effects of air pollution on socio-ecological justice
and human quality of life (Kumar et al., 2015).
However, despite the fact that air quality sensors performances allow a new strategy, resulting in
fast responses, low operating costs and high efficiencies that cannot be achieved with only
conventional approaches, much research remains to be done in order to integrate these new
technologies, particularly on the quality check of the sensors performance against conventional
methods in field exercises (Aleixandre and Gerboles, 2012; Mead et al., 2013). The application of
new sensors side by side with standardised equipment in field studies will allow assessing the
reliability and uncertainty of these microsensors, especially regarding an accurate detection of
pollutant concentration peaks.
There is a current trend worldwide to increase the collection of air quality data beyond fixed
monitoring stations, although legislation to regulate the usability of this data is not in place yet.
This paper will discuss how the use of this type of new micro-sensors could affect bthe air quality
network designed for Fortaleza in Brazil.
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