Us Air Pollution: A Global Concern

Air pollution is a pressing issue in the United States, with far-reaching consequences for public health, the environment, and the economy. The US has made significant progress in improving air quality since 1980, but certain human activities continue to contribute to poor air quality and pose risks to human health. This includes vehicle emissions, industrial processes, agricultural practices, and natural sources such as wildfires. These factors disproportionately impact minority communities, with people of color being more likely to reside in areas with higher levels of air pollution and facing greater health risks. Addressing air pollution in the US requires a multifaceted approach, including policy interventions, technological advancements, and community-driven initiatives, to mitigate its impact on both human well-being and the environment.

Vehicle emissions

Ozone is a harmful pollutant that can cause serious health issues. It is created when pollutants from vehicles and other sources react chemically in the presence of sunlight. The frequent sunny days in Los Angeles, for example, contribute to higher levels of ozone formation, exacerbating the city's air pollution problem. Los Angeles has been ranked as the city with the worst ozone pollution in the nation for 25 out of the past 26 years.

To address vehicle emissions and improve air quality, the Environmental Protection Agency (EPA) has implemented standards commonly known as Tier 3. These standards aim to reduce tailpipe and evaporative emissions from passenger cars, light-duty trucks, medium-duty passenger vehicles, and some heavy-duty vehicles. The Tier 3 standards also include a gasoline sulfur standard to reduce the sulfur content of gasoline, enabling more effective emission control systems and cleaner fuel options.

In addition to regulatory efforts, initiatives such as the National Clean Diesel Campaign and Clean School Bus USA aim to reduce diesel emissions from existing engines and minimize pollution from school buses, respectively. Despite these measures, air pollution from vehicles continues to pose a significant challenge, and the changing climate is making it increasingly difficult to maintain progress in improving air quality.

Industrial processes

Petrochemical plants, for example, process hydrocarbons derived from crude oil and natural gas into petrochemicals, which are essential for many everyday products. However, these plants emit airborne pollutants such as PM2.5, sulfur dioxide, nitrogen oxides, VOCs, carbon monoxide, and hazardous air pollutants (HAPs) like formaldehyde, all of which impact air quality and health. Commercial transportation also emits pollutants like PM2.5, nitrogen oxides, sulfur dioxide, VOCs, and greenhouse gases like carbon dioxide and methane, contributing to climate change.

The industrial composition of the economy plays a significant role in air pollution. Industries central to production, such as electricity generation, have higher output and pollution levels. While some sectors have reduced air pollution, others have not contributed as much to this progress. For instance, the fossil fuels sector remains the most polluting industry globally, with emissions continuing to rise. The use of coal for energy generation, in particular, has been a significant source of air pollution, producing nitrogen oxides, sulfur dioxide, particulate matter, black carbon, and smog.

Additionally, certain demographic groups are disproportionately affected by industrial air pollution. A Yale University study found that Hispanics, African Americans, and Asians were exposed to higher levels of pollutants, with people of color more likely to reside near toxic waste facilities and hazardous industrial sites. Los Angeles, with its geographical basin structure, has the most contaminated air in the country, with diesel engines, ports, motor vehicles, and industries contributing to poor air quality.

Climate change

In 2021, nearly 102 million people in the United States lived in areas with poor air quality. Climate-driven changes in weather conditions are expected to worsen this situation, increasing exposure to harmful pollutants. Wildfires, which are becoming more frequent and lasting longer due to climate change, release smoke that pollutes the air and spreads across regions. This smoke contains particulate matter that can impair visibility, disrupt outdoor activities, and worsen respiratory illnesses.

The United States has taken several measures to address air pollution and mitigate its contribution to climate change. The Environmental Protection Agency (EPA) has implemented initiatives such as the Clean Air Act and the Clean Power Plan to reduce greenhouse gas emissions and improve air quality. The Clean Air Act has successfully lowered levels of common pollutants, including particles, ozone, lead, carbon monoxide, nitrogen dioxide, and sulfur dioxide. The Act also encourages the deployment of clean technologies and innovations that reduce emissions.

Additionally, the EPA has proposed rules to reduce methane emissions and smog-forming pollution in the oil and gas industry, as well as regulations to limit greenhouse gas pollution from vehicles. The Clean Power Plan aims to reduce carbon pollution from power plants and provides customized goals for states to address climate change. These efforts reflect the United States' commitment to leading global efforts to combat climate change.

Individuals can also play a role in reducing air pollution and mitigating climate change. John Walke, director of the Clean Air team at NRDC, emphasizes the importance of reducing gasoline consumption, choosing more fuel-efficient or electric vehicles, and supporting leaders who prioritize clean air and responsible climate actions.

Natural sources

Air pollution is a mix of hazardous substances from both human-made and natural sources. Natural sources of air pollution in the US include:

Wildfires

Wildfires, which are often caused by people, release smoke and other pollutants into the air. These fires can be caused by natural phenomena, such as lightning strikes, but human activity, including arson and the improper disposal of cigarettes, is a significant contributor. Summertime wildfires can reduce visibility and have negative biological effects on US National Park Service (NPS) areas.

Volcanic Eruptions

Volcanic eruptions emit ash and gases, including methane, into the atmosphere. While volcanoes are not a common occurrence in the US, the country does have several active volcanoes, including Mount St. Helens in Washington and Kilauea in Hawaii.

Decomposing Organic Matter

Gases, such as methane, are emitted from decomposing organic matter in soils. This is a natural part of the carbon cycle, where organic matter is broken down by microorganisms, releasing carbon dioxide and methane as byproducts.

Wind-borne Pollutants

Wind can carry pollutants over short or long distances before they cause harmful impacts. For example, parks downwind of power plants that lack modern pollution controls can experience increased smog and haze. Additionally, pollutants from other countries can be transported thousands of miles and affect air quality in the US.

While natural sources of air pollution can be significant, they typically do not create ongoing pollution problems compared to human-made sources.

Racial disparities

Despite progress toward cleaner air in the US, a growing body of research suggests that racial and ethnic disparities persist in exposure to air pollution and its associated health effects. Studies have consistently found that racial and ethnic minority groups, particularly non-Hispanic Black and Hispanic communities, experience higher exposure to air pollution and face greater health risks as a result.

One study, published in Nature in 2022, linked 17 years of demographic data with fine particulate pollution data across the US. It found stark disparities in air pollution exposure among racial/ethnic and income groups, with racial disparities holding across all income levels. Specifically, White people were exposed to lower than average concentrations from emission source types, while people of color experienced greater than average exposures, with race appearing to be a significant factor for exposure in most regions.

These disparities are not merely a result of income differences. A 2012 study found that unemployed people, those with low incomes or low education levels, and non-Hispanic Blacks were more likely to live in areas with higher particle pollution exposure. However, the study also noted that different racial/ethnic and income groups were exposed to varying types of particles, which may have differing health impacts. Indeed, a 2021 study found that disparities in health impacts associated with nitrogen dioxide and particulate matter widened over the last decade. Communities of color experienced significantly higher pediatric asthma rates and premature mortality rates due to these pollutants compared to predominantly White communities.

The causes of these disparities are rooted in systemic racism and discriminatory policies such as redlining, which have historically located the least White areas near heavily polluting sources like factories and highways. Additionally, certain racial and ethnic minority groups, such as Blacks and Hispanics, contribute less to air pollution through their consumption of goods and services but bear a disproportionate burden of its negative consequences.

Addressing these disparities requires targeted policies and regulations that allocate resources and interventions to historically overburdened communities. It is essential to recognize the role of systemic racism in creating and perpetuating these inequities to effectively tackle environmental injustice and reduce the disproportionate impact of air pollution on racial and ethnic minorities in the US.

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