Pollutants Released by Vehicles Burning Fossil Fuels
“Energy-related fossil-fuel combustion in high- and middle-income countries
and biomass burning in low-income countries accounts for most of the global
air pollution, generating 85% of airborne respirable particulate pollution and
almost all sulfur dioxide and nitrogen oxide emissions to the atmosphere [17].
Also emitted are black carbon, polycyclic aromatic hydrocarbons (PAH),
nitrogen and sulfur dioxides, mercury, and volatile chemicals that form ground-
level ozone (O3)”.
Chemical Reactions in the Burning of Fossil Fuels
The primary chemical reaction involved in the burning of fossil fuels is combustion. In
ideal conditions, the combustion of hydrocarbons in fuel with oxygen from the air results
in carbon dioxide (CO2) and water (H2O):
Hydrocarbon+Oxygen→CO2+H2OHydrocarbon+Oxygen→CO2+H2O
However, due to variations in engine conditions and fuel compositions, combustion is
often incomplete, leading to the production of CO, NOx, and other pollutants.
Particulate Matter and Its Connection to Vehicles
Particulate matter (PM) is a mixture of tiny solid particles and liquid droplets suspended
in air. PM can be directly emitted from vehicle exhausts as well as formed in the
atmosphere from the reactions of gases such as NOx and SO2. Vehicles, especially diesel
engines, are significant sources of PM2.5 (particles with a diameter of 2.5 micrometers or
smaller) and PM10 (particles with a diameter of 10 micrometers or smaller), which can
cause respiratory and cardiovascular diseases.
“Measurements are made using an optical particle counter (OPC), a differential mobility
analyzer (DMA)/condensation nucleus counter (CNC) combination, and a pair of
microorifice uniform deposit impactors (MOUDIs). The sources tested with this system
include catalyst-equipped gasoline-powered light-duty vehicles, noncatalyst gasoline-
powered light-duty vehicles, and medium-duty diesel trucks. Chemical composition
analysis demonstrates that particles emitted from the gasoline-powered vehicles tested are
largely composed of organic compounds while particles emitted from diesel engines
contain roughly equal amounts of organic compounds and elemental carbon. The particle
mass distributions from all mobile sources tested have a single mode that peaks at
approximately 0.1−0.2 μm particle diameter. Of the two diesel vehicles tested, the vehicle
with the lowest fine particle emissions rate released the largest number of ultrafine
particles, a finding similar to that of Bagley et al. (Characterization of fuel and
aftertreatment device effects on diesel emissions; Technical Report 76; Health Effects
Institute: Cambridge, MA, 1996). Particle size distribution measurements taken
throughout the FTP urban driving cycle used to test all of the vehicles described in this
paper reveal that particulate mass emission rates and particulate size distributions from
the vehicles tested here are similar during the cold start and hot start segments of the
driving cycle”.
Volatile Organic Compounds (VOCs) and Their Connection to Vehicles
VOCs are organic chemicals that easily vaporize at room temperature. Vehicles emit
VOCs through fuel evaporation and incomplete combustion. These compounds are
significant because they can react with NOx in the presence of sunlight to form ground-
level ozone, a key component of smog, which is harmful to human health and the
environment.
In China, “on-road motor vehicle emissions, solvent use and industrial processes are three
dominant sources of VOCs emissions in China (Bo et al., 2008, Li et al., 2014, Wei et al.,
2008, Wei et al., 2001, Wei et al., 2014).Among the total anthropogenic sources of VOCs,
motor vehicle emissions account for > 25% (Wei et al., 2001) in 2010 in China, which is
larger in urban area (Wang et al., 2013a, Wang et al., 2015). In recent decades, the vehicle
population in China has rapidly grown, especially in megacities (Editorial Board of China
Auto Market Almanac, 2013), which shows increasing importance to air pollution.
Hence, it is important to investigate VOCs emissions from on-road motor vehicles”.
“Sixteen of twenty-seven publications reported detailed datasets of VOCs source profiles.
There were 90 VOCs species in source profile in the datasets, as shown in Table 1S,
which can be divided into alkanes, alkenes, alkynes, aromatics, halocarbons (x-VOC) and
oxygenated VOCs (OVOCs). Based on the reported data, the present study further
summarized the VOCs source profile of on-road vehicle emissions focusing on the
comparisons among different studies and the potential impact of fuels”.
Cars, Vehicles, and Climate Change
Vehicles contribute to climate change mainly through the emission of greenhouse gases
such as CO2, a byproduct of fossil fuel combustion. CO2 traps heat in the atmosphere,
leading to global warming and climate change. Vehicles also emit methane (from the
evaporation and incomplete combustion of fuel) and nitrous oxide (from the high-
temperature combustion in engines), both potent greenhouse gases.
“Transport accounts for 26% of global CO2 emissions and is one of the few industrial
sectors where emissions are still growing. Car use, road freight and aviation are the
principal contributors to greenhouse gas emissions from the transport sector and this
review focuses on approaches to reduce emissions from these three problem areas. An
assessment of new technologies including alternative transport fuels to break the
dependence on petroleum is presented, although it appears that technological innovation
is unlikely to be the sole answer to the climate change problem. To achieve a stabilisation
of greenhouse gas emissions from transport, behavioural change brought about by policy
will also be required. Pressure is growing on policy makers to tackle the issue of climate
change with a view to providing sustainable transport. Although, there is a tendency to
focus on long-term technological solutions, short-term behavioural change is crucial if
the benefits of new technology are to be fully realised”.
Public Transit
Public transit refers to shared transportation services that are available for use by the
general public, including buses, trains, subways, and trams. It is designed to reduce the
number of individual vehicles on the road, thereby decreasing traffic congestion,
pollution, and greenhouse gas emissions.
Benefits of Public Transit
Public transit offers numerous benefits, including:
Health: Reduces air pollution, leading to lower rates of respiratory and
cardiovascular diseases.
Economy: Public transit can be more cost-effective for individuals and society by
reducing fuel consumption, traffic congestion, and the need for extensive road
infrastructure.
Environment: Decreases greenhouse gas emissions and pollutants, contributing to
cleaner air and combating climate change.
Accessibility: Provides mobility options for those who cannot drive or afford a
personal vehicle, promoting social inclusion.
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+ Frederica Perera. Pollution from Fossil-Fuel Combustion is the Leading Environmental
Threat to Global Pediatric Health and Equity: Solutions Exist( Int J Environ Res Public
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+ Michael J. Kleeman, James J. Schauer, and Glen R. Cass Environmental Science &
Technology 2000 34 (7), 1132-1142.( Size and Composition Distribution of Fine
Particulate Matter Emitted from Motor Vehicles | Environmental Science & Technology
(acs.org)).
+ Wang Hong-li, Jing Sheng-ao, Lou Sheng-rong, Hu Qing-yao, Li Li, Tao Shi-kang,
Huang Cheng, Qiao Li-ping, Chen Chang-hong. Volatile organic compounds (VOCs)
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https://www.sciencedirect.com/science/article/abs/pii/S0048969717317047).
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