Gasoline's Impact: Air Pollution Explained

Gasoline is a highly volatile mixture of natural hydrocarbons and other organic chemicals derived from crude petroleum. It is mostly used in cars, light trucks, and motorcycles, but also in small aircraft, boats, and other watercraft, and landscaping and construction equipment. Gasoline causes air pollution both before and after combustion. Before combustion, humans can be exposed to gasoline through vapour and gasoline-engine exhaust when they breathe, and it is also possible to absorb it through the skin or ingest it. After combustion, burning a gallon of gasoline produces about 19 pounds of carbon dioxide (CO2). In addition, gasoline contains benzene, which is a carcinogen that can cause eye, skin, and lung irritation in the short term and blood disorders in the long term.

Gasoline leaks

The impact of these leaks is twofold. Firstly, they emit methane, a greenhouse gas with an extremely high warming potential—over 80 times that of carbon dioxide over a 20-year period. Secondly, leaked gasoline contains hazardous air pollutants, such as benzene, toluene, m,p-xylene, and hexane, which are known to cause adverse health effects. These pollutants are present in the gas used across California, and their impact is not limited by region or provider. In fact, a study found that the benzene emissions from distribution-level gas infrastructure in California were equivalent to the benzene emissions of nearly 60,000 cars.

The presence of these hazardous pollutants in natural gas has serious implications for human health. Exposure to benzene, for example, can cause eye, skin, and lung irritation in the short term and blood disorders in the long term. The impact of these pollutants is not limited to outdoor settings; they can also accumulate indoors, with gas stoves creating benzene concentrations comparable to secondhand smoke.

To address the issue of gasoline leaks, the United States has committed to reducing greenhouse gas emissions by 61-66% below 2005 levels by 2035. This includes mandating the detection and repair of leaks from oil and gas wells, pipelines, and other facilities. Additionally, the Clean Air Act Amendments of 1990 required the use of cleaner-burning reformulated gasoline to reduce air pollution in metropolitan areas with high levels of ground-level ozone pollution.

Benzene and other chemicals

Benzene is a natural part of crude oil and gasoline and is also present in cigarette smoke. It is one of the top 20 most produced and used chemicals in the United States. It is used to make other chemicals, including plastics, resins, lubricants, rubbers, dyes, detergents, drugs, and pesticides. In the past, it was also used as an industrial solvent and as a gasoline additive, but these uses have been greatly reduced in recent decades.

The Environmental Protection Agency (EPA) classifies benzene as a carcinogen and limits the percentage of benzene allowed in gasoline to a yearly average of 0.62% by volume (with a maximum of 1.3%). The EPA also limits concentrations of benzene in drinking water to 5 parts per billion (ppb).

Benzene exposure can cause eye, skin, and lung irritation in the short term and blood disorders in the long term. It can also affect the immune system by changing blood levels of antibodies and causing the loss of white blood cells. The level of benzene poisoning depends on the amount, duration of exposure, and the person's age and medical condition.

Other chemicals present in gasoline include over 500 saturated and unsaturated hydrocarbons, with approximately 150 being detectable. Modern gasoline contains, on average, approximately 14% aromatics, 80% paraffins, and 6% olefins, and often small amounts of alcohols, ethers, detergents, corrosion inhibitors, antioxidants, and oxygenates.

Gasoline leaks can occur at gas stations, in pipelines, or in underground storage tanks, contributing to air pollution. Leaks can also occur from open gas tanks on vehicles. The combustion of gasoline in engines produces carbon dioxide (CO2), a greenhouse gas that contributes to global warming and climate change.

To reduce pollution from gasoline use, the EPA has implemented various measures, including requiring emissions-control devices and cleaner-burning engines. In 1995, the Clean Air Act Amendments required cleaner-burning reformulated gasoline to reduce air pollution in metropolitan areas with significant ground-level ozone pollution.

Gasoline-contaminated soil and water

Soil contamination by gasoline can have detrimental effects on the engineering properties of the soil, including its density and plasticity. Gasoline molecules mix with soil particles, altering the behaviour of water in the soil. This can result in increased water requirements for the soil to exhibit plastic properties and impact the flow of water through the soil. The extent of these changes depends on the type of soil, with sandy and silty soils being particularly susceptible to gasoline contamination.

The presence of gasoline in the soil can also lead to the release of harmful vapours, which can accumulate in enclosed spaces such as basements and living areas. These vapours can cause adverse health effects, including nose and throat irritation, headaches, dizziness, nausea, and breathing difficulties. The impact of gasoline vapours on human health is primarily due to individual chemicals such as benzene, a known carcinogen, and other volatile organic compounds.

Water sources can also become contaminated with gasoline, leading to potential exposure through bathing, laundry, drinking, and food preparation. Municipal water treatment processes can remove traces of gasoline from source water, but private wells may be at risk of contamination, especially if located near gas stations. Groundwater contamination with gasoline can have long-lasting effects, as the remediation process can be complex and time-consuming.

The health risks associated with gasoline-contaminated soil and water are not limited to immediate exposure. Long-term exposure to high levels of benzene, a component of gasoline, has been linked to an increased risk of leukemia. Additionally, the combustion of gasoline in vehicles contributes significantly to air pollution, particularly in metropolitan areas with high ground-level ozone pollution.

To mitigate the impact of gasoline-contaminated soil and water, various treatment technologies have been developed. These technologies focus on volatilizing the contaminants, taking into account factors such as the boiling points of the compounds, soil type, depth to groundwater, and mean annual precipitation. Regulatory agencies have established maximum allowable concentrations of gasoline range organics in soil, with specific algorithms designed to determine cleanup levels based on local factors.

Car exhaust

Burning a gallon of gasoline produces about 19 pounds of carbon dioxide. In 2022, combustion emissions from aviation and motor gasoline in the US accounted for approximately 22% of total energy-related CO2 emissions. Carbon dioxide is a greenhouse gas that contributes to global warming and climate change.

In addition to gases, car exhaust emits solid and liquid particles that contribute to air pollution. These particles, known as soot, are made up of tiny fragments of chemicals, soil, smoke, dust, or allergens. Soot can penetrate the lungs and bloodstream, exacerbating respiratory conditions such as bronchitis and increasing the risk of heart attacks.

The health impacts of car exhaust pollutants are significant. Long-term exposure to air pollution has been linked to various diseases, including respiratory and cardiovascular issues, cancers, and other health problems. Vulnerable populations, such as children, the elderly, and individuals with pre-existing conditions, are especially susceptible to the adverse effects of car exhaust pollutants.

To mitigate the pollution caused by car exhaust, governments and regulatory bodies have implemented various measures. For example, the Environmental Protection Agency (EPA) in the US has mandated the use of emissions-control devices and cleaner-burning engines. The Clean Air Act and its amendments also play a crucial role in reducing air pollution by setting standards for engines and fuels to produce fewer emissions.

Ground-level ozone

Ozone at ground level is harmful because it can trigger a variety of health problems, especially for children, the elderly, and people with pre-existing lung diseases like asthma. It aggressively attacks lung tissue by chemically reacting with it and can cause respiratory illnesses, including bronchitis and emphysema. Research has also linked ozone exposure to premature mortality, with an estimated one million premature deaths annually due to respiratory diseases. In addition to its impacts on human health, ground-level ozone can damage vegetation, decrease crop productivity, and harm synthetic materials and textiles.

The levels of ground-level ozone tend to be highest near urban centers and on hot, sunny days. This is because urban areas have higher emissions from cars, power plants, and other sources, and the formation of ground-level ozone is dependent on the interaction of pollutants with sunlight. Strategies to reduce ground-level ozone focus on methane reductions and cutting atmospheric pollution from these sources.

To protect human health and the environment, it is crucial to limit ground-level ozone and its precursor pollutants, NOx and VOCs. The EPA in the United States has designated national ambient air quality standards (NAAQS) for ozone and works with states to improve air quality through state implementation plans (SIPs). By reducing emissions and following air quality guidelines, we can mitigate the harmful effects of ground-level ozone and improve the health and well-being of people, especially those vulnerable to its respiratory impacts.

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