Cars' Impact: Understanding Air Pollution Sources

Cars, trucks, buses, and other vehicles are a major source of air pollution. In the United States, cars, trucks, and SUVs make up 57% of transportation sector greenhouse gas emissions, with California's transportation sector accounting for nearly 80% of nitrogen oxide pollution and 80% of smog-causing pollutants. Burning gasoline and diesel fuel creates harmful byproducts, including nitrogen oxides, carbon monoxide, hydrocarbons, formaldehyde, and benzene. These pollutants have been linked to adverse health effects, with exposure disproportionately impacting low-income communities and communities of color. To reduce air pollution from vehicles, individuals can choose more fuel-efficient vehicles, maintain their vehicles, and drive less, while governments can implement emission control programs and support the development of clean vehicle technologies.

Cars burning gasoline and diesel fuel

Gasoline fumes escape into the air even when pumping gasoline into fuel tanks. The combustion of gasoline also emits carbon dioxide, a greenhouse gas that contributes to global warming and climate change. Burning a gallon of gasoline produces about 19 to 20 pounds of carbon dioxide. While carbon dioxide is vital for life on Earth, burning fossil fuels releases far more carbon dioxide than the planet can absorb. This excess carbon dioxide forms a heat-trapping layer around the Earth, contributing to rising global temperatures.

Diesel engines, on the other hand, consume a complex mix of petroleum components, producing pollutants such as nitrogen oxides and hydrocarbons. A small amount of unburned fuel exits the engine, forming larger particles in the atmosphere when they react with airborne dust. Diesel vehicles contribute significantly to nitrogen oxide emissions, with 60% of NOx emissions in the US attributed to diesel engines.

However, it is important to note that newer vehicles emit less air pollution than older ones due to advancements in technology and stricter emissions standards. Electric, hybrid, and fuel-efficient vehicles are becoming more accessible and affordable, reducing pollution from motor vehicles. Additionally, driving habits, such as observing speed limits and accelerating gradually, can influence the amount of pollution emitted by a vehicle.

Greenhouse gases and climate change

Greenhouse gases are gases that trap heat in the atmosphere, contributing to global warming and climate change. The burning of fossil fuels, such as gasoline and diesel, by cars and other vehicles is a significant source of greenhouse gas emissions, particularly carbon dioxide (CO2). According to the US EPA, a typical passenger vehicle emits about 4.6 metric tons of CO2 per year, and highway vehicles release about 1.5 billion metric tons of greenhouse gases annually. This varies depending on factors such as fuel type, fuel economy, and mileage.

In addition to CO2, vehicles emit other greenhouse gases such as methane (CH4) and nitrous oxide (N2O) from their tailpipes. The production and distribution of gasoline also contribute to GHG emissions. Electric vehicles (EVs) have no tailpipe emissions, but emissions are created during the production and distribution of the electricity used to power them.

The transportation sector plays a significant role in greenhouse gas emissions. In the EU, transport was responsible for about a quarter of total CO2 emissions in 2019, with road transportation accounting for 71.7%. In the US, light-duty vehicles like passenger cars, trucks, and SUVs make up 57% of transportation sector GHG emissions, with California's cars, trucks, and SUVs contributing 70%.

To reduce greenhouse gas emissions from vehicles, individuals can opt for more fuel-efficient vehicles, such as electric or hybrid models. Driving habits can also make a difference, with slower speeds, gradual acceleration, and reduced mileage helping to lower emissions. Additionally, maintaining vehicles and keeping them in good repair can ensure they run as cleanly and efficiently as possible.

On a broader scale, initiatives such as California's zero-emission vehicle (ZEV) standards and the EU's European Green Deal roadmap aim to reduce greenhouse gas emissions from the transport sector.

Health and environmental risks

Cars, trucks, and buses produce air pollution throughout their life cycle, including pollution emitted during vehicle operation and fuel production. Additional emissions are associated with the refining and distribution of fuels and, to a lesser extent, the manufacturing and disposal or recycling of the vehicle.

Health Risks

Vehicle emissions are harmful to human health. They contribute to the risks of morbidity and mortality for drivers, commuters, and individuals living near roadways. These emissions include:

• Carbon monoxide (CO): This colorless, odorless, and poisonous gas is formed by the combustion of fossil fuels such as gasoline. When inhaled, CO blocks oxygen from reaching the brain, heart, and other vital organs.
• Nitrogen oxides (NOx): These are formed by the combustion of nitrogen in the air and contribute to the formation of smog and ozone, which are harmful to human health.
• Sulfur dioxide (SO2): This pollutant is formed by burning sulfur-containing fuels, especially diesel and coal. SO2 can form fine particles that pose a significant health risk to young children and asthmatics.
• Particulate matter (PM): Fine particles, such as soot, can penetrate deep into the lungs and pose a serious threat to human health.
• Other pollutants: Vehicles also emit volatile organic compounds (VOCs), hydrocarbons (HCs), benzene, and formaldehyde, which have harmful health effects.

The health risks of air pollution from vehicles are serious. Poor air quality increases respiratory ailments like asthma and bronchitis and heightens the risk of life-threatening conditions like cancer. Particulate matter alone is responsible for up to 30,000 premature deaths each year.

Environmental Risks

Vehicle emissions also pose significant risks to the environment and contribute to climate change. Carbon dioxide (CO2) is the principal greenhouse gas emitted by vehicles, and while it is not directly harmful, it is released in quantities that overwhelm the Earth's natural absorption systems. This excess CO2 forms a heat-trapping layer, contributing to global warming and climate change.

Traffic congestion increases vehicle emissions and further degrades air quality, particularly near major roadways. This has led to excess morbidity and mortality for those living in these areas. Additionally, marginalized communities near freight centers and heavily traveled roadways are disproportionately exposed to higher levels of air pollution and may lack the resources to adapt or relocate.

Mitigation Strategies

To mitigate the health and environmental risks associated with air pollution from cars, several strategies can be employed:

• Adopting cleaner vehicles and fuel technologies: This includes driving electric, hybrid, or fuel-efficient vehicles that produce fewer emissions.
• Maintaining vehicles: Regular maintenance and repairs ensure that emission controls are functioning properly, reducing pollution.
• Driving habits: Observing speed limits, accelerating gradually, and anticipating the road ahead can help reduce fuel consumption and emissions.
• Reducing mileage: Driving less, walking, or biking to destinations can significantly reduce vehicle emissions.

Vehicle maintenance and efficiency

To address this issue, individuals can take several measures to maintain and improve the efficiency of their vehicles. One of the most effective ways is to drive the most fuel-efficient vehicle that meets their needs. With the increasing availability of hybrid and all-electric vehicles, drivers can significantly reduce their emissions. These vehicles burn less fuel, resulting in lower emissions of harmful combustion by-products. Additionally, driving habits play a role in reducing pollution. Observing speed limits, accelerating gradually, and avoiding racing from red light to red light can help decrease fuel consumption and lower emissions.

Regular vehicle maintenance is also essential for minimizing air pollution. Following the owner's manual for recommended maintenance, such as oil changes, ensures that the car runs as cleanly and efficiently as possible. Newer vehicles have complex emission controls, and any malfunction can lead to increased pollution. Therefore, it is crucial to address check engine lights and take the vehicle to a qualified technician for repairs or maintenance. Properly inflating tires according to the owner's manual can also improve fuel efficiency and reduce pollution.

Furthermore, advanced emission reduction technologies, such as catalysts and electronic fuel injection, are now available for commercial-grade machinery, resulting in significantly less pollution. States like California have implemented stricter emission standards, with many other states and countries following suit. These standards, along with initiatives like California's Zero Emission Vehicle (ZEV) program, aim to reduce vehicle emissions and encourage the adoption of cleaner energy alternatives.

While older vehicles tend to produce more pollution due to deteriorating pollution controls, policies can help accelerate the retirement of these older models. Exhaust standards, such as those set by the Clean Air Act, play a pivotal role in reducing emissions by setting maximum emission rates for new vehicles. Additionally, technologies like catalytic converters can eliminate up to 100% of exhaust emissions, further contributing to cleaner vehicles.

Government standards and initiatives

The US federal government has implemented various standards and initiatives to reduce air pollution caused by cars. The Clean Air Act of 1970 gave the Environmental Protection Agency (EPA) the authority to regulate pollution from cars and other transportation sources. Since then, the EPA has set and implemented emissions standards for various vehicles, including passenger cars, heavy-duty trucks, buses, and construction equipment. These standards have led to the development of modern automotive technologies, such as computers, fuel injection, and on-board diagnostics, resulting in cleaner and more efficient vehicles.

The EPA has also provided resources to help consumers make environmentally informed choices when purchasing vehicles. The Green Vehicle Guide, available on the EPA website, lists pollution levels for recent passenger vehicles, allowing consumers to compare and choose the cleanest and most fuel-efficient option for their needs. Additionally, the EPA has promoted initiatives to reduce unnecessary idling of vehicles, such as the Clean School Bus Program, which helps reduce school bus idling and children's exposure to diesel exhaust.

At the state level, initiatives have been undertaken to adopt zero-emission vehicle (ZEV) standards. For example, New York and seven other states have joined an initiative to put 3.3 million ZEVs on the road by 2025, aiming to expand consumer awareness and demand for these vehicles. California has also implemented stringent standards, such as the California Heavy-Duty Low NOx Omnibus and California Phase 2 Greenhouse Gas Standards, which other states are considering adopting.

Overall, these government standards and initiatives have contributed to significant improvements in air quality, despite increasing vehicle miles traveled and population growth. The transportation sector remains a significant source of carbon pollution, and continued efforts are needed to address this issue and promote the adoption of cleaner technologies.

Frequently asked questions