Air Pollution In America: The Main Culprits

Air pollution is a pressing issue in the United States, with about 120 million people living in counties with unhealthy levels of air pollution, according to the 2023 State of the Air report. This complex problem stems from a variety of sources, including vehicle emissions, fuel oils, natural gas, manufacturing by-products, power generation, and chemical production. Natural sources, such as wildfires and volcanoes, also contribute to air pollution. The adverse health effects of air pollution are well-documented, impacting both respiratory and cardiovascular systems, with certain demographic groups bearing a disproportionate burden. While progress has been made in reducing emissions, the challenge of protecting public health persists, especially with the added complexities of climate change.

Natural sources, like wildfires and volcanoes, contribute to air pollution

Natural sources, such as wildfires and volcanoes, significantly contribute to air pollution in America. Wildfires, for instance, produce particle pollution, a mixture of gaseous pollutants, hazardous air pollutants (HAPs), water vapour, and particle pollution. Fine particles, generally 2.5 micrometres in diameter or smaller, are the main pollutant emitted by wildfire smoke, making up about 90% of the total particle mass. These fine particles can have serious health effects, affecting the lungs and heart when inhaled. Wildfire smoke also contains hazardous pollutants such as polycyclic aromatic hydrocarbons (PAHs) and carbon monoxide.

The impact of wildfires on air quality and public health has been the subject of extensive research. Studies have shown that exposure to wildfire smoke can have similar health effects to those attributed to fine particles from other sources, such as urban pollution. This is particularly concerning for individuals with asthma or allergies, as the extra pollutants can aggravate their symptoms and trigger asthma attacks.

Volcanic eruptions also release large quantities of greenhouse gases and aerosols into the atmosphere. These emissions include water vapour (H2O), carbon dioxide (CO2), sulphur dioxide (SO2), hydrogen sulfide (H2S), carbon monoxide (CO), hydrogen chloride (HCl), and hydrogen fluoride (HF). The release of these gases forms massive clouds that accumulate in the atmosphere, leading to outgassing or off-gassing.

The effects of volcanic pollution can be detrimental to the Earth's biosphere, including both animals and plant life. For example, the eruption of Mount St. Helens in 1980 released up to 3750 tons per day of sulphur dioxide, causing an international pollution event. The prevailing winds carried the ash cloud across the United States in three days and around the world in 15 days. Additionally, the hydrogen fluoride released during volcanic eruptions can impair the surrounding biosphere, including vegetation and livestock that consume ash-coated grass.

Vehicle emissions, fuel oils, and natural gas used to heat homes are primary sources of human-made air pollution

Vehicle emissions, fuel oils, and natural gas used to heat homes are significant contributors to air pollution in America. The transportation sector, including vehicles, is one of the largest sources of carbon pollution in the country. Historically, new cars emitted high levels of pollutants, such as hydrocarbons (13 grams per mile), nitrogen oxides (3.6 grams per mile), and carbon monoxide (87 grams per mile). California researchers in the 1950s were the first to establish a link between air pollution and cars, attributing the smog over Los Angeles to vehicle emissions.

Since then, the U.S. Environmental Protection Agency (EPA) has played a pivotal role in reducing transportation-related air pollution. The EPA has set and implemented stringent emissions standards for various vehicles, including passenger cars, heavy-duty trucks, buses, and even lawn and garden equipment. These standards have spurred technological innovations in the auto industry, leading to the development of new emission control technologies. As a result, cities across America have witnessed improved air quality, with visible smog being significantly reduced.

Fuel oils and natural gas production also contribute to air pollution and have been associated with adverse health impacts. States with significant oil and gas activity, such as Texas, Pennsylvania, Ohio, Oklahoma, and Louisiana, have experienced higher levels of pollution from this sector. Additionally, states with limited oil and gas production, like Illinois and New York, have also been affected due to the far-reaching nature of air pollution. The health consequences of fuel oils and natural gas pollution include early deaths and childhood asthma cases, with pollutants such as NO2 and O3 being major contributors.

Furthermore, natural gas used in homes, buildings, and businesses across North America often contains hazardous air pollutants, including benzene, toluene, and hexane. These pollutants pose risks to both human health and the climate. Leaks from residential natural gas appliances are common, and the presence of climate-warming methane and other air pollutants can negatively affect indoor air quality. While odorants are added to natural gas to aid in leak detection, their varying concentrations across locations can hinder effective detection, allowing hazardous air pollutants to persist undetected.

Air pollution is a cause of respiratory and cardiovascular issues, including asthma and heart disease

Air pollution is a pressing issue in the United States, with a range of causes, including smog, soot, greenhouse gases, and other harmful substances. These pollutants have detrimental effects on human health, particularly on respiratory and cardiovascular systems, even causing early death in some cases.

Respiratory issues: Air pollution can cause and exacerbate respiratory conditions such as asthma, allergic rhinitis, chronic obstructive pulmonary disease (COPD), and lung cancer. People with asthma are more susceptible to the effects of air pollution, as small particles and irritating gases can irritate their airways and worsen symptoms. Outdoor air pollution, particularly in cities with high traffic and the burning of fossil fuels, can trigger asthma attacks and lead to more hospital visits for those with respiratory issues.

Additionally, vulnerable populations, including children, older adults, and those with pre-existing respiratory conditions, are at an increased risk of experiencing the negative consequences of air pollution. The impact of air pollution on respiratory health is complex, involving multiple physiological pathways that lead to inflammation, oxidative stress, and changes in the immune system.

Cardiovascular issues: Air pollution is also a contributing factor to cardiovascular disease, which is the leading cause of death in the United States, especially for those over 65. Fine particulate matter (PM2.5) in air pollution can increase the risk of cardiovascular events, including heart attacks. Those with pre-existing cardiovascular conditions, such as ischemic heart disease or heart failure, are at a heightened risk of adverse health effects from air pollution exposure.

Furthermore, air pollution and climate change are interconnected, with climate change worsening respiratory and cardiovascular health. As climate change intensifies extreme weather events, air pollution levels are projected to rise, exacerbating the health impacts on vulnerable populations.

People of colour are disproportionately affected by air pollution and its health consequences

The United States has made significant progress in improving air quality, with a 78% reduction in the six principal air pollutants between 1970 and 2023. However, air pollution remains a pressing issue, with approximately 140 million people living in counties with pollution levels above the primary NAAQS in 2023. People of colour are disproportionately affected by air pollution and its health consequences.

A 2021 study by researchers at the EPA-funded Center for Air, Climate, and Energy Solutions found that people of colour in the United States breathe more particulate air pollution on average, regardless of income level or region. This finding expands on existing evidence that African Americans, Hispanics, Asians, and other people of colour are disproportionately exposed to fine particulate matter (PM2.5). Exposure to PM2.5 can lead to serious health issues, particularly for those with pre-existing health conditions, younger and older individuals, and other vulnerable populations.

The study's co-author, Julian Marshall, a professor of civil and environmental engineering, attributed the disparities in exposure to systemic racism. Historical housing policies and other factors have resulted in people of colour being pushed into areas with high pollution levels. This environmental injustice has been recognised as a social justice issue, with movements seeking to address flawed environmental policies that have long harmed communities of colour and low-income communities.

Furthermore, people of colour are more susceptible to the health consequences of air pollution. A 2016 study of New Jersey residents found a higher risk of premature death from long-term exposure to particle pollution in communities with larger African American populations, lower home values, and lower median incomes. Similar studies in Atlanta, GA, revealed that particle pollution increased the risk of asthma attacks in zip codes with higher poverty rates and among individuals eligible for Medicaid.

The cumulative impact of air pollution and its health effects exacerbates existing inequalities and underscores the need for land use and public health reforms. Addressing the root causes of these disparities, such as discriminatory housing policies and the disproportionate location of pollution sources near disadvantaged communities, is crucial for ensuring environmental justice and equitable living conditions for people of colour.

The EPA has implemented standards and regulations to reduce air pollution and improve air quality

The Clean Air Act (CAA) is a federal law that regulates air emissions from stationary and mobile sources. It authorises the Environmental Protection Agency (EPA) to establish National Ambient Air Quality Standards (NAAQS) to protect public health and welfare and to regulate emissions of hazardous air pollutants. The EPA has been successful in achieving large reductions in national emissions of air toxics.

Furthermore, the EPA has reduced the benzene and sulfur content in gasoline and diesel fuel, respectively, and has issued standards for medium- and heavy-duty vehicles that will improve fuel efficiency and cut carbon pollution. The EPA's Clean Air Markets Division (CAMD) runs programs that reduce air pollution from power plants to address environmental issues such as acid rain, ozone, and particle pollution. The EPA also tracks a range of emissions data, including how much of each pollutant is emitted from various pollution sources, and has developed statistical approaches to account for weather's influence on ozone and fine particles.

The Clean Power Plan, finalised by the EPA in 2015, provides strong but achievable standards for power plants and customised goals for states to reduce carbon pollution. It reflects each state's energy mix while maintaining energy reliability and affordability. The EPA has also prohibited certain uses of hydrofluorocarbons, a class of potent greenhouse gases, in favour of safer alternatives, and has proposed amendments to the Montreal Protocol to achieve international reductions in these gases.

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