Cars: Understanding Their Pollution Emissions

Cars emit a variety of pollutants that contribute to air pollution and climate change. The primary source of car pollution is the combustion of fuel in the engine, which releases exhaust fumes containing carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM), and volatile organic compounds (VOCs). These emissions have significant impacts on both human health and the environment. While electric vehicles offer a cleaner alternative, the transportation sector, including cars, remains a major contributor to global warming and air quality issues.

Carbon dioxide

The amount of CO2 emitted by a car varies depending on factors such as the type of fuel, fuel economy, and the number of miles driven. On average, a typical passenger vehicle emits about 4.6 metric tons of CO2 per year, with each gallon of gasoline burned creating approximately 8,887 grams of CO2. This equates to about 400 grams of CO2 emitted per mile. The production and disposal of a car can also contribute to CO2 emissions, in addition to the emissions generated during its use.

In 2019, passenger cars accounted for 61% of total CO2 emissions from road transport in the EU. To address this issue, the EU has introduced new CO2 emission targets, aiming for a 55% reduction in emissions from cars by 2030 and zero emissions for new passenger cars by 2035. Electric vehicles are becoming increasingly popular, and while their production and disposal may currently have a higher environmental impact, they are still overall cleaner than vehicles running on petrol or diesel.

To reduce CO2 emissions from cars, individuals can opt for more fuel-efficient vehicles, carpool, or use public transportation, walk or cycle. Additionally, choosing low-carbon fuels and improving vehicle technologies can also help lower emissions. By implementing these strategies, we can work towards reducing the impact of cars on climate change and improving air quality.

Carbon monoxide

The health risks associated with carbon monoxide exposure are significant. It is a leading cause of poisoning, with one-third of cases resulting in death. Carbon monoxide poisoning can occur when individuals are exposed to high concentrations of the gas, which can happen quickly with gas-powered automobile engines. The lethal consequences of carbon monoxide exposure are tragically illustrated by the hundreds of people who die each year from carbon monoxide poisoning caused by a running vehicle. This can occur when a vehicle is left running in an enclosed space, such as a garage, or when a vehicle has a defective exhaust system.

To mitigate the risks associated with carbon monoxide emissions, it is crucial to maintain proper vehicle maintenance and ensure that exhaust systems are functioning correctly. Electric vehicles, such as electric trucks and buses, offer a promising solution to reducing carbon monoxide emissions. By eliminating tailpipe pollution and adopting renewable energy sources, electric vehicles can significantly lower global warming emissions compared to their fossil fuel-powered counterparts.

In addition to implementing technological advancements, such as electric vehicles, there are also behavioural practices that individuals can adopt to reduce carbon monoxide exposure. These include limiting the use of automobiles, carpooling, avoiding congested traffic, and combining errands to reduce overall driving time. By combining technological innovations and behavioural changes, we can effectively reduce carbon monoxide emissions and create a safer and healthier environment for ourselves and our communities.

Nitrogen dioxide

NOx has been regulated since the 1960s, and the introduction of mandatory catalytic converters in 1992 has helped to significantly reduce NOx emissions. However, in 2015, Volkswagen was found to be manipulating the performance of its diesel cars' emissions control systems, bringing the damaging effects of NOx on public health into the spotlight.

NOx has harmful direct and indirect effects on human health. It irritates the lungs, weakens the body's defences against respiratory infections, and contributes to the formation of ground-level ozone, a main ingredient in smog. Ground-level ozone irritates the respiratory system, causing coughing, choking, and reduced lung capacity.

Since 2007, the absolute emissions of NO2 have been decreasing, and the amount of NO2 emitted decreases as vehicle mileage increases. Electric vehicles, in particular, have helped to reduce NO2 emissions, as they produce no harmful tailpipe pollution.

Volatile organic compounds

VOCs are emitted from the combustion of fossil fuels, such as gasoline, and the evaporation of fuel. They are also emitted from interior vehicle materials, such as cabin interior materials and standing emissions from the engine, gas tank, and hoses when the car is not operating. VOCs have been linked to various health issues, including respiratory and cardiovascular diseases, and an increased risk of cancer.

The concentration of VOCs in vehicle cabins can be higher than in buildings and is influenced by factors such as interior temperature, humidity, ventilation, and vehicle age. VOC levels can be particularly high when a vehicle has been parked in direct sunlight, as this increases the interior temperature and causes the volatilization of various chemical substances.

Oxygenated volatile organic compounds (OVOCs) are a significant contributor to VOC emissions from vehicles, especially diesel vehicles. OVOCs contribute to a larger fraction of total VOC emissions in diesel vehicles compared to gasoline vehicles.

The emission factors of VOCs have been observed to generally decrease with the improvement of emission standards, particularly for gasoline vehicles. However, the influence of emission standards on VOC emissions from diesel vehicles is more diverse.

Particulate matter

PM2.5, or fine particulate matter, is of particular concern due to its impact on human health and mortality. It has been linked to various diseases of the pulmonary, cardiac, vascular, and neurological systems, including acute lower respiratory illness, cerebrovascular disease, ischaemic heart disease, chronic obstructive pulmonary disease, and lung cancer. Studies have estimated that approximately 3.3 million premature deaths worldwide are attributable to outdoor air pollution, with PM2.5 being the most significant contributor. In the United States alone, PM2.5 from road transportation is associated with roughly 54,730 premature deaths annually.

The concentration of PM2.5 in the air can be influenced by various factors, including carbon dioxide (CO2) emissions, land cover, and population density. On-road transportation is a primary source of PM2.5 emissions, and an increase in road traffic directly contributes to higher concentrations of particulate matter in the atmosphere. For example, a study found that a 6.17 billion-kilometre increase in on-road transportation per square kilometre was associated with a 1-microgram/cubic metre increase in PM2.5 concentration in the contiguous United States.

Electric vehicles, such as electric cars, trucks, and buses, offer a promising solution to reducing particulate matter emissions. Unlike traditional vehicles powered by fossil fuels, electric vehicles produce zero tailpipe emissions and significantly lower global warming emissions. The adoption of electric fleets in cities across the United States, such as New York and Los Angeles, demonstrates a commitment to reducing tailpipe pollution and improving air quality.

While electric vehicles are a step towards reducing particulate matter emissions, it is important to acknowledge that the impact of road transportation on PM2.5 concentrations varies across different regions. For instance, a unit increase in on-road transportation in New England or the Mideast has a smaller impact on PM2.5 concentrations compared to other regions. This variation highlights the need for region-specific policies and interventions to address the issue of particulate matter pollution effectively.

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