Air Pollution: A Declining Global Threat?

Air pollution is a serious health and environmental issue, and a leading risk factor for death. It is caused by a combination of indoor and outdoor particulate matter and ozone. While air pollution emissions have decreased substantially over the last few decades, it continues to threaten human health and welfare. According to a study by Columbia University Mailman School of Public Health, air pollution emissions reductions vary depending on demographics, with racial and socioeconomic disparities. In the EU, air pollutant emissions continue to fall, but more action is needed to achieve zero-pollution targets.

Air pollution emissions have decreased substantially in the US and EU

Air pollution is a serious health and environmental issue, and is a leading risk factor for death and disease worldwide. It is therefore encouraging that air pollution emissions have decreased substantially in the US and EU.

In the US, total emissions of the six principal air pollutants dropped by 78% between 1970 and 2023. This is despite a 321% increase in GDP, a 194% increase in vehicle miles travelled, a 42% increase in energy consumption, and a 63% increase in population over the same period. The US has also phased out production of substances that deplete the ozone layer under Clean Air Act provisions enacted to implement the Montreal Protocol. These substances include CFCs, halons, methyl chloroform, and carbon tetrachloride.

The US has also seen a 98% decrease in airborne lead concentrations between 1980 and 2005, and a further 30% decrease in lead emissions between 2008 and 2017. From 1990 to 2017, emissions of air toxics declined by 74%, largely driven by federal and state implementation of stationary and mobile source regulations, and technological advancements.

In the EU, the Fourth Clean Air Outlook report published by the European Commission shows that air pollutant emissions continue to fall. Over the past two decades, the EU has achieved substantial reductions in the emissions of four main air pollutants. This is a result of EU clean air legislation, source legislation, and joint action taken by the EU with national, regional, and local authorities. However, ammonia emissions, which come predominantly from intensive livestock farming, manure and slurry management, and fertiliser application, have not fallen significantly. Only four Member States (Estonia, Finland, Greece, and Italy) are on course to achieve all their 2030 emission reduction commitments.

Despite this positive progress, it is important to note that air pollution continues to pose a threat to human health and welfare. In the US, approximately 140 million people lived in counties with pollution levels above the primary NAAQS in 2023. In the EU, more action is needed to achieve the Commission's zero-pollution ambition and commitment to achieving sustainable prosperity.

Despite this, air pollution continues to be a serious health and environmental risk

While air pollution emissions have decreased substantially over the last few decades, it continues to be a serious health and environmental risk. Air pollution is one of the leading risk factors for death and contributes to the global disease burden. It is a combination of outdoor and indoor particulate matter and ozone and is a risk factor for many of the leading causes of death, including heart disease, stroke, lower respiratory infections, lung cancer, diabetes, and chronic obstructive pulmonary disease (COPD). In recent years, air pollution has contributed to one in ten deaths globally.

In the United States, air pollution rates have declined, but pockets of inequities remain. Certain demographics, such as racial/ethnic and socioeconomic groups, have experienced disproportionate decreases in air pollution emissions. This is due to disparities in the implementation of policies and regulations, as well as differences in pollution source sectors. For example, the industry, energy generation, and agricultural sectors have been identified as significant contributors to air pollution exposure disparities.

In the European Union, air pollutant emissions continue to fall, according to the Fourth Clean Air Outlook report. However, ammonia emissions, which contribute to excessive nitrogen presence in water ecosystems and the formation of fine particulate matter, have remained flat or even increased in some Member States. Only four Member States are on course to achieve their 2030 emission reduction commitments, and additional action is needed to limit emissions of PM2.5 and meet the EU's zero-pollution ambition.

Despite the progress made in reducing air pollution emissions, it continues to pose a serious threat to public health and the environment. Elevated risks persist in urban areas, near industrial facilities, and in regions with high transportation emissions. Furthermore, certain pollutants can cause harm even at very low levels, and the health impacts of air pollution are not limited to sensitive groups but can affect everyone as pollution levels increase.

Socio-demographic characteristics influence the magnitude of change in air pollution

While air pollution emissions have decreased substantially over the last few decades, the magnitude of change varies due to socio-demographic characteristics. Research has shown that there are racial, ethnic, and socioeconomic disparities in air pollution emissions reductions, with poorer people and some racial and ethnic groups facing higher exposure to pollutants.

A study by researchers at Columbia University Mailman School of Public Health found that the magnitude of change in air pollution varies by demographics. The study, which analyzed air pollution emissions data from six pollution source sectors, found that there were racial/ethnic and socioeconomic disparities in air pollution emissions reductions, particularly in the industry and energy generation sectors.

Another study by the American Lung Association found that higher-income blacks faced a greater risk from air pollution than lower-income whites, suggesting that factors such as chronic stress as a result of discrimination may play a role. Multiple large studies have shown that low socioeconomic status is linked to a higher risk of premature death from fine particle pollution.

Additionally, a 2008 study of Washington, DC, found that areas with higher Medicaid enrollment had poorer air quality and higher rates of asthma, while a 2016 study of New Jersey residents found that communities with larger African American populations, lower home values, and lower median incomes had a higher risk of dying early from long-term exposure to particle pollution.

The European Commission has also recognized that air pollution disproportionately affects certain socio-demographic groups. While air pollutant emissions in the EU have been decreasing, ammonia emissions, which contribute to excessive nitrogen presence in water ecosystems, have remained flat or even increased in some Member States.

The Clean Air Act has helped reduce air pollution emissions

The Clean Air Act has been instrumental in reducing air pollution emissions over the past few decades. Enacted 50 years ago, the Clean Air Act is a federal law that gives the US Environmental Protection Agency (EPA) the authority to regulate air pollutants and polluting industries. The Act has helped reduce air pollution emissions by setting national health-based standards for air quality and emissions, which are based on the latest scientific and technological information.

The Clean Air Act has been amended several times, with significant amendments being made in 1977 and 1990, to address the changing nature of air pollution and to strengthen the EPA's ability to regulate and reduce emissions. The 1977 amendments included provisions to protect areas with clean air and tightened the rules around automobile emissions, a major source of pollution. The 1990 amendments represented a major shift, with the introduction of a national permits program and the implementation of the Montreal Protocol to phase out chemicals depleting the ozone layer.

The Clean Air Act has led to dramatic improvements in air quality, with reductions in the levels of common pollutants such as particles, ozone, lead, carbon monoxide, nitrogen dioxide, and sulfur dioxide. Between 1990 and 2020, national concentrations of these pollutants improved significantly, with an 86% reduction in lead concentrations and a 73% improvement in carbon monoxide levels. The Act has also prompted the deployment of clean technologies and innovations that reduce emissions and control costs. For example, new cars, trucks, and non-road engines now use state-of-the-art emission control technologies, and power plants have cut emissions that cause acid rain.

The Clean Air Act has also had economic benefits, with a focus on clean air and a healthy economy going hand in hand. The Act has reduced healthcare costs and improved productivity by reducing absences from work or school due to air pollution-related illnesses. Additionally, the Clean Air Act partnership programs have improved energy efficiency, reduced oil imports, and saved money.

While the Clean Air Act has been successful in reducing air pollution emissions, there are still areas for improvement. There are racial/ethnic and socioeconomic disparities in air pollution emissions reductions, particularly in the industry and energy generation sectors. Additionally, while air pollution emissions have decreased substantially, pockets of inequities remain, with approximately 140 million people in the US living in counties with pollution levels above the primary NAAQS in 2023.

Indoor air pollution is not regulated under the Clean Air Act

While the Clean Air Act has been instrumental in reducing air pollution in the United States, it does not address indoor air quality. The Act gives the Environmental Protection Agency (EPA) the authority to regulate air pollutants and polluting industries, but this does not extend to indoor spaces.

The Clean Air Act, enacted 50 years ago, was a response to the toxic pollution that plagued American cities, where smog was a visible and tangible presence. The law set National Ambient Air Quality Standards (NAAQS) to protect public health and welfare and gave the EPA the power to regulate emissions of hazardous air pollutants. The six major pollutants regulated by the NAAQS are ozone (O3), particulate matter (PM), carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), and lead (Pb).

However, the EPA does not have the authority to regulate indoor air quality. While they offer assistance and information on indoor air quality issues such as mold, radon, and formaldehyde, there are currently no federal regulations or standards for indoor airborne mold contaminants. This means that the responsibility for maintaining healthy indoor air quality falls on individuals and businesses, rather than being subject to federal oversight and intervention.

The exclusion of indoor air pollution from the Clean Air Act has implications for public health. Indoor air quality can be affected by various factors, including mold, radon, and emissions from household products and activities. Poor indoor air quality can lead to respiratory issues and other health problems, particularly for vulnerable individuals such as children, the elderly, or those with pre-existing health conditions.

While the Clean Air Act has been successful in reducing outdoor air pollution, the lack of regulation for indoor air quality highlights the need for additional measures to ensure that the air people breathe in indoor spaces meets health and safety standards. This may involve the development of separate legislation or policies specifically targeting indoor air quality, or the expansion of the Clean Air Act to include indoor spaces.

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