Air Pollution's Dramatic Rise: What's Causing This?

Air pollution is a pressing global health and environmental issue, causing millions of deaths each year. It is a complex problem with natural and human emission sources, including fossil fuels, transportation, manufacturing, and industrial activity. While there has been a general decline in air pollution in some countries, the overall trend is complex and varies across regions. For instance, the State of the Air 2025 report revealed that 46% of Americans live in areas with failing grades for unhealthy ozone or particle pollution levels, indicating a dramatic increase in air pollution in certain regions. This increase can be attributed to factors such as extreme heat, drought, and wildfires, which have exposed more people to harmful pollutants.

Indoor air pollution

The use of inefficient and polluting fuels and technologies, such as open fires, kerosene, biomass (wood, animal dung, and crop waste), and coal, is a significant contributor to indoor air pollution. This is particularly prevalent in low-income countries, where solid fuels are relied upon for cooking. The World Health Organization (WHO) has issued guidelines for indoor air quality, recommending clean fuels and technologies such as solar, electricity, biogas, liquefied petroleum gas (LPG), natural gas, and alcohol fuels.

The health effects of indoor air pollution can be experienced immediately after exposure or may manifest years later. Immediate symptoms can include irritation of the eyes, nose, and throat, headaches, dizziness, and fatigue. Prolonged exposure to indoor air pollutants can lead to more severe health issues, including respiratory diseases, heart disease, and cancer. Certain groups, such as women and children, who typically spend more time near the domestic hearth, bear the brunt of the health consequences associated with indoor air pollution.

To mitigate indoor air pollution, it is essential to identify and address the sources of pollution, improve ventilation, and transition to cleaner fuels and technologies. Organizations like the WHO play a crucial role in providing guidelines and capacity-building efforts to promote the adoption of cleaner alternatives and protect the health and well-being of people worldwide.

Outdoor air pollution

Historical data reveals that pollution levels tend to increase as cities develop, following a typical pathway of rising emissions that eventually peak and then decline. For instance, London experienced a two-century-long deterioration in air quality, with particulate matter in its air doubling between 1700 and 1900. However, recent decades have shown a different trend, with a decline in total air pollution death rates since 1990, halving in recent decades. This improvement is primarily driven by a significant reduction in indoor air pollution, while outdoor pollution improvements have been more modest.

The sources of outdoor air pollution are diverse and include transportation, power generation, industry, waste management, and agriculture. Particulate matter (PM), a common proxy indicator for air pollution, includes harmful components like sulfates, nitrates, ammonia, sodium chloride, black carbon, mineral dust, and water. Other pollutants such as carbon monoxide, ground-level ozone, nitrogen dioxide, and lead also contribute to poor air quality.

Addressing outdoor air pollution requires concerted action by policymakers and individuals. Successful strategies include implementing clean technologies, improving waste management practices, transitioning to clean power sources, promoting energy efficiency, adopting cleaner transportation options, and supporting urban greening initiatives. The Clean Air Act in the United States, enforced by the Environmental Protection Agency (EPA), has played a crucial role in reducing emissions and improving air quality over several decades. Similar regulatory efforts and policies are essential to mitigate the harmful impacts of outdoor air pollution on human health and the environment.

Air pollution in the US

The Clean Air Act, first implemented in 1963 and significantly updated in 1970, has played a pivotal role in mitigating air pollution in the US. The Act focuses on lowering levels of several harmful pollutants, including particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. Since then, the US Environmental Protection Agency (EPA) has been committed to protecting public health by reducing pollutant emissions and improving air quality. The EPA has established standards and regulations to control emissions from various sources, including vehicles, factories, and power plants.

According to the EPA, national emissions of ambient air pollutants and their precursors have substantially decreased since 1980. This reduction is attributed to various factors, including the phase-out of leaded gasoline, controls on emissions of lead compounds, and technological advancements. Between 1970 and 2023, while the gross domestic product, vehicle miles travelled, energy consumption, and population grew significantly, total emissions of the six principal air pollutants dropped by 78%.

However, despite these improvements, air pollution remains a pervasive problem. The American Lung Association's "State of the Air" 2025 report revealed that approximately 156 million people (46% of the population) lived in places that received failing grades for unhealthy levels of ozone or particle pollution. This issue disproportionately affects communities of colour, who are more likely to be exposed to unhealthy air and suffer from chronic conditions that increase their vulnerability to air pollution.

Several factors contribute to the persistence of air pollution in the US. Extreme heat, drought, and wildfires, driven by climate change, are exacerbating pollution levels and posing risks to public health. Additionally, while overall emissions have decreased, certain industries and sources continue to produce significant pollution. For example, coal-fired power plants and emissions from diesel trucks remain significant contributors to air pollution.

Addressing air pollution in the US requires a multifaceted approach. It entails strict enforcement of existing regulations, such as the Clean Air Act, and the continued development of emissions standards by the EPA. Additionally, mitigating climate change impacts, promoting technological innovations, and ensuring equitable air quality for all communities are crucial aspects of combating air pollution and safeguarding public health.

Air pollution and health

Air pollution is a serious public health and environmental issue that affects people worldwide. It develops in two contexts: indoor (household) air pollution and outdoor air pollution. Both types of pollution have been linked to a range of adverse health effects, with indoor air pollution contributing to a greater number of deaths globally.

Indoor Air Pollution

Indoor air pollution is a significant problem, particularly in low-income countries, due to the reliance on solid fuels for cooking. It is a combination of direct toxicity and particulate matter, with 3.1 million deaths attributed to household air pollution. The use of solid fuels, such as wood, biomass, or fossil fuels like coal, can result in the formation of soot, or black carbon (BC), which is harmful to human health.

Outdoor Air Pollution

Outdoor air pollution is influenced by a range of factors, including industrial activity, technological developments, fuel consumption, vehicle miles traveled, and other human activities. The combustion of fossil fuels, for example, leads to the emission of sulfur dioxide (SO2) and nitrogen oxides, which contribute to particle formation and have adverse respiratory effects. Communities of color are disproportionately affected by unhealthy outdoor air and are more likely to suffer from chronic conditions that increase their vulnerability to air pollution, such as asthma, diabetes, and heart disease.

Health Effects of Air Pollution

The health effects of air pollution are far-reaching and can lead to premature death and hospitalizations. Fine particle pollution, or fine particulate matter (PM2.5), has been linked to increased hospital admissions for heart attacks, strokes, and respiratory illnesses. Ozone, an invisible gas formed from emissions of nitrogen oxides and volatile organic compounds, can cause shortness of breath, aggravate lung diseases, and lead to permanent lung damage through long-term exposure.

Progress and Improvements

Despite the challenges posed by air pollution, significant progress has been made in reducing emissions and improving air quality. Many countries have successfully reduced air pollution levels, resulting in the prevention of early deaths. The implementation of standards and regulations, such as the Clean Air Act in the United States, has played a crucial role in decreasing emissions and improving public health. Technological advancements have also contributed to the decline in emissions, with innovations in vehicle technology and the reduction of benzene content in gasoline.

Air pollution by country

Air pollution is one of the world's most pressing health and environmental issues, affecting nearly every organ in the body and causing a range of health problems, including heart disease, stroke, lower respiratory infections, lung cancer, diabetes, and chronic obstructive pulmonary disease (COPD). It is a particular challenge in emerging and developing countries, where it is often linked to industrialisation.

While air pollution is a global issue, it disproportionately affects certain countries and regions. Here is a look at the situation in several countries:

United States

Despite making significant progress in cleaning the air since the 1970s, the United States continues to grapple with air pollution, which poses risks to human health and the environment. The Environmental Protection Agency (EPA) has been instrumental in reducing emissions of common air pollutants and their precursors since 1980. Between 1980 and 2005, airborne lead concentrations decreased by 98% due to the phase-out of leaded gasoline and other regulatory efforts. The EPA has also successfully reduced benzene content in gasoline and established stringent emission standards for diesel and gasoline engines, benefiting urban areas. From 2008 to 2017, emissions decreased by an additional 30%. However, in 2023, the US still emitted about 66 million tons of pollution, contributing to ozone formation and particle deposition.

Low and Middle-Income Countries

In low-income countries, indoor air pollution rates tend to be high due to the reliance on solid fuels for cooking. As countries transition from low to middle-income, outdoor air pollution often increases due to industrialisation. This shift in income levels and industrialisation can lead to a significant increase in overall air pollution levels.

Global Trends

According to the World Health Organization, the recommended limit for particulate matter (PM2.5) is 10 micrograms per cubic meter. However, many countries exceed this guideline, with some even surpassing it by over ten times. Air pollution caused approximately 4.5 million premature deaths in 2019, and an additional 2 million premature deaths were attributed to indoor air pollution that year.

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