1. Venue: Allson Klana Hotel, Nilai
2. Date: October 2009
Monitoring of Benzene Concentrations Within Indoor Environment of Cars
Nor Azam Ramli , *Wesam Ahmed Al Madhoun, , Ahmad Shukri Yahaya,
Clean Air Research Group, School of Civil Engineering, Universiti Sains Malaysia,
Penang, Malaysia.
Correspondent Author: *wsah79@yahoo.com
Abstract
Benzene is a member of an important group of aromatic Volatile Organic Compounds
(VOCs), emitted mainly from cars, and a known carcinogenic. In this study Benzene was
measured at different motor vehicles. The aim of this study is to investigate the air quality
inside the motor vehicles which were parking in sunshine by monitoring of benzene
concentrations. Monitoring was done using Indoor Air Quality Meter (IAQM).The results
show that the mean concentrations of Benzene were ranging from 16 to 242 ppb inside the
cars that were monitored throughout the study. OSHA has set a permissible exposure limit of
0.5 part of benzene per million parts of air (0.5 ppm) in the workplace during an 8-hour
workday, 40-hour workweek. The results show that the current concentrations of TVOC and
Benzene were higher than the permissible limits set by OSHA.
Keywords: Benzene, Emissions, Inside Cars, OSHA, Permissible Limit.
1.0 Introduction
Benzene, Toluene, Ethylbenzene and Xylene (BTEX) are elements of an important group of
aromatic Volatile Organic Compounds (VOCs), usually emitted from various sources. BTEX
play a vital role in the tropospheric chemistry and poses health risk to human (Khoder, 2007).
Benzene is known as a carcinogenic compound, which is emitted mainly from petrol-fuelled
cars and thus found in all urban areas ( Skov et al , 2001).
The relative contributions of light-duty vehicles (LDV) and heavy duty vehicles (HDV) to the
total emissions indicated that aldehydes, BTEX and alkanes are mainly produced by LDV,
while HDV dominated emissions of CO, NOx, SO2, and PM10 (Schmid et al , 2001). VOC
also emitted in the interior of motor vehicles which is made of a wide variety of synthetic
materials (Buters et al., 2007).
In motor vehicles fuel, Benzene is the additive. Benzene is mostly produced by chemical
reactions occurring during combustion of petrol in the engine. This study will monitor
Benzene inside motor vehicles which were parking in the sunshine.
The US Occupational Safety and Health Administration (OSHA) has set a permissible
exposure limit of 0.5 part of benzene per million parts of air (0.5 ppm) in the workplace
during an 8-hour workday, 40-hour workweek. The short term exposure limit for airborne
benzene is 5 ppm for 15 minutes (OSHA website, 2008). Meanwhile the European legislation
set an annual mean of 5gm−3 (Esteve-Turrillas et al., 2007).
2.0 Research background
Air pollution is defined as the presence in the outdoor and or indoor atmosphere of one or
more contaminants or combinations thereof in such quantities and of such duration as may be
or may tend to be injurious to human, plant, or animal life (Wark et al , 1998).
The rapid growth of the Malaysian economy over the past 27 years, due to the development
of industrial estates, free trade zones, thermal power plants and petroleum industries, which
could result in the deterioration of the environment if due care is not taken. The severity of
the environmental problems associated with air quality degradation may result from, vehicles
emissions and industries, particulate matters from stacks and exhaust, dust from quarrying
activities, construction projects and open burning (Hassan, et al , 2000).
In several large cities, the air pollutants are increasing with time and at times exceed the
levels prescribed by the national ambient air quality standards. This has been shown from
monitoring and studies on ambient air quality. There are three major sources of air pollution
viz., mobile, stationary and open burning. Figure 1 illustrates the percentage contribution of
each source in Malaysia (Afroz et al. , 2003).
0.8% Open burning of
solid wastes
3% Industrial production
processes
5% Industrial
fuel burning
0.2% Domestic and
commercial furnaces
9% (Power
stations)
82% (Mobile source)
Figure 1: Sources of Air Pollution in Malaysia Adopted from
(Afroz et al., 2003).
There has been marked increase in motor vehicles ownership in Malaysia. In 2006, there are
6.91 million registered cars running on the roads (Road and Transport Department of
Malaysia, 2008).
The EPA Complex Model indicated that benzene emissions account for nearly 70 percent of
the total toxic emissions from vehicles using conventional gasoline and that exhaust benzene
accounts for nearly 90 percent of the total benzene (Whitten, et al, 2004).
In Malaysia reduction of lead content began in July 1985 from the initial of 0.84 grams/liter
to 0.5 grams/liter and further reduced to 0.15 grams/liter in January 1990. Benzene levels is
limited to 5% by volume (Euro 2) by year 2004 and will be further reduced to 1% (Euro 4) by
year 2009 (Firdaus, et al, 2006).
The estimated world-wide average emissions of VOCs are about 1347 million tons (Mt)/year
from biogenic sources and 462 Mt/year from anthropogenic sources. Ambient total
concentration of airborne VOCs (155 species) in urban and suburban areas have been
reported to be in the range 16.2–1033 μg/m3. Some VOCs have toxic health effects
depending on duration and levels of exposure, even at μg/m3 concentrations (e.g., exposure
to BTEX at high levels can cause respiratory, neurological, genetic and excretory system
damage) (Badjagbo, et al , 2007).
Figure 2: BTEX concentrations in Different Cities Worldwide Adopted from (Martins
et al., 2007)
Statistics on transport-related pollution death for Penang and Malaysia is yet to be available
for reference purposes, figures in London shows that each year, Londoners lose about 34,000
years of life from transport related pollution and this high figure is very much related to the
average traffic speed in central London of 16 kmph due to the ever worsening congestion. In
addition, soot from diesel pollution also leads to 27,000 non-fatal heart attacks and more than
400,000 emergency room visits in the US annually (Penang Economic Monthly, 2005).
Benzene at the busy road was not fully understood.
WHO has estimated that a lifetime exposure of 0.17 g/m3 gives rise to an excess risk of
developing leukemia of 1 per 1,000,000 inhabitants based on toxic-kinetic models (Penang
Economic Monthly, 2005). In Sweden, relationship between acute myeloid leukemia (AML)
and car density was found; the incidence of AML was 5.5 in regions that have more than 20
cars / km2. Low benzene concentrations in ambient air are likely to be dangerous; other
studies have also found an association between traffic density and incidence of leukemia in
children (Rommelt, et al, 1999).
3.0 Method
Monitoring of Benzene was carried out using Direct Sense Indoor Air Quality (IAQ) Meter
equipped with Photo Ionization Detector (PID) sensor, which is capable of measuring TVOC,
CO, CO2, Temperature and Relative Humidity, simultaneously. Proactive indoor air quality
surveys are being implemented efficiently and easily due to Direct Sense IAQ Monitors from
GrayWolf. It can identify potential IAQ issues before they become problems and respond
immediately to complaints with the high accuracy, extremely advanced and the most intuitive
portable IAQ meters and test instrumentation available today (Gray Wolf Sensing Solutions
website, 2008). IAQ was used to measure the benzene concentrations in 11 cars with various
ages. The monitoring was made for 30 minutes with closed door condition.
4.0 Results and discussion
Benzene concentrations were measured by using Indoor Air Quality Meter. Measurements
carried out in eleven cars belong to students and staff of the engineering campus, USM. The
results are shown in figure 3.
24
2
300
19
2
18
6
200
150
57
71
73
100
37
Benzene Conc. (ppb)
250
16
21
25
50
2
4
Su
nn
ey
_8
a_
on
da
_9
H
84
3
To
yo
t
ot
on
_0
3
Pr
Pr
ot
on
_0
3
_0
4
Ie
nk
on
ot
on
_0
7
Pr
H
on
da
_0
5
a_
0
el
is
K
Fi
at
_
09
0
Car Brand _Year of Production
Figure 3: Benzene concentration inside motor vehicles
The results show that there is strong relation between benzene concentrations and the
production year of the motor vehicles where old cars emit higher concentrations, where a car
that was produced in the year 1982 emitted 242 ppb while a car that was produced in 2009
emit 16 ppb.
24
2
300
200
19
2
18
6
11
5
150
10
3
Benzene Conc. (ppb)
250
100
50
0
Toyota_84
Honda_92
Sunney_84
Near Highway
Urban
Figure 4: Comparison between Benzene concentrations inside cars and Benzene
emitted in different locations
Fig.4 shows a comparison between the benzene concentrations inside motor vehicles and
benzene emitted from different locations where the results show that the benzene contraction
inside the old cars higher than the benzene concentrations’ in the urban areas and even near
the highway
5.0 Conclusion
The results of this study show that people can exposed to a certain level of benzene
which will be risky for them on the long run, this motivate us to refresh the air inside the care
by opening the windows before starting our trip. Levels of benzene inside the motor vehicles
can be reduced by avoid parking in the sunshine areas where high temperature create the
suitable conditions for emitting benzene from the car elements such as, “dashboard, seats and
door panels” which mostly made from plastics, synthetic fabrics.
Acknowledgements
The authors will like to express their sincere appreciation to the Universiti Sains Malaysia for
the financial support under the scheme of USM Fellowship and the Research University
Grant (1001.PAWAM.811066). Special thanks go to my colleagues and the staff in the
School of Civil Engineering, USM, for their cooperation in the monitoring campaign.
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