Air Pollution's Alarming Rise: A Historical Perspective

Air pollution is a critical global health and environmental concern, impacting the lives and well-being of people worldwide. While there have been notable improvements in air quality in some regions, particularly in high-income countries, air pollution remains a significant and growing threat in many parts of the world. Over the years, the increasing industrialization and energy consumption have contributed to rising levels of outdoor air pollution, while indoor air pollution continues to affect low-income communities. The changing climate, with more frequent extreme weather events, is also exacerbating air quality issues, making it challenging to sustain progress in reducing pollution levels.

The Clean Air Act: a 50-year success story

Air pollution has been a concern for centuries, but it escalated in the early 20th century due to greater electricity consumption, increased industrial production, and a more automobile-based society. The Clean Air Act, enacted 50 years ago, has been instrumental in reducing air pollution and improving air quality in the United States. Here is a 50-year success story of the Clean Air Act:

The Early Years

Fifty years ago, the United States Congress passed the Clean Air Act to address the air pollution crisis. The Act gave the Environmental Protection Agency (EPA) the authority to regulate air pollutants and polluting industries. The law set in motion a series of successful environmental protection programs that continue to benefit citizens today.

Reducing Harmful Pollutants

The Clean Air Act has successfully reduced harmful pollutants in the air. Between 1990 and 2018, carbon monoxide levels dropped by 74%, ground-level ozone declined by 21%, and lead decreased by 82% from 2010. The combined emissions of six common pollutants (particulate matter, sulfur dioxide, nitrogen oxides, volatile organic compounds, carbon monoxide, and lead) have dropped by 74% across the United States.

Health Improvements

The reduction in air pollution has led to significant health improvements. The Clean Air Act has prevented more than 435,000 premature deaths and millions of cases of respiratory diseases such as chronic bronchitis and asthma. Particulate air pollution reductions have added 1.5 years to the life expectancy of the average American since 1970.

Environmental and Economic Benefits

The Clean Air Act has also had environmental and economic benefits. It has helped protect the ozone layer, reduced the risk of acid rain, and improved soil, freshwater bodies, and vegetation health. The financial legacy of the Act has stimulated the economy, with benefits estimated at almost $2 trillion.

Technological Advancements

The Clean Air Act has spurred technological advancements in emissions control. The auto industry has developed new emission control technologies, and modern automotive technologies like computers, fuel injection, and on-board diagnostics have resulted in cleaner and higher-quality vehicles.

Ongoing Challenges and Adaptations

While the Clean Air Act has been a success, air pollution continues to be a concern. Recent data shows an increase in harmful pollutants, and the United States remains a leading country for premature pollution-related deaths. The Act has undergone several updates to reflect technological advancements and an evolving understanding of safe pollutant levels. Additionally, the push and pull of different presidential administrations have impacted the Act's enforcement.

Climate change: wildfires and particle pollution

Air pollution is caused by solid and liquid particles and certain gases that are suspended in the air. These particles and gases can come from car and truck exhaust, factories, dust, pollen, mould spores, volcanoes, and wildfires. The solid and liquid particles suspended in the air are called aerosols. Many aerosols enter the atmosphere when we burn fossil fuels, such as coal and petroleum, and wood. Some of the particles and gases come directly from these sources, but others form through chemical reactions in the air.

Ozone is a major cause of air pollution in cities. Ground-level ozone is created when sunlight reacts with certain chemicals that come from sources of burning fossil fuels, such as factories or car exhaust. When particles in the air combine with ozone, they create smog, a type of air pollution that makes it difficult to see outdoors.

A warming climate is increasing some types of fire activity, leading to larger and more destructive fires, more intensive firefighting efforts, and widespread smoke. The size and number of wildfires in the United States have been recorded since 1983 by the National Interagency Fire Center. Over the past 20 years, the amount of land area burned each year has increased as wildfires have grown larger, while the number of fires each year has remained fairly constant. Warmer nighttime temperatures are a major contributing factor, allowing fire activity to persist overnight.

Wildfire smoke can travel thousands of miles and put millions of people at risk. The particulate matter in wildfire smoke is linked to numerous adverse health impacts. Tiny particles in smoke irritate the eyes and throat and can contribute to health problems such as reduced lung function, asthma, and cardiovascular disease. According to the U.S. Environmental Protection Agency, differently-sized particles are associated with different health effects. The commonly regulated size classifications are PM10 (inhalable particles with diameters of 10 micrometers and less) and PM2.5 (respirable particles with diameters of 2.5 micrometers and less).

NASA uses satellites orbiting Earth to monitor air pollution. NASA's Terra and Aqua satellites detect active wildfires twice each day. Scientists studied this data over a 21-year span and found that extreme wildfires have become more frequent, more intense, and larger. The largest increase in extreme fire behaviour was in the temperate conifer forests of the Western U.S. and the boreal forests of northern North America and Russia.

Regulatory processes: reducing air pollution

Air pollution has been a significant concern for decades, with emissions of air pollutants playing a crucial role in various air quality issues. While there has been progress in improving air quality, certain human activities continue to contribute to the degradation of the atmosphere. To address this issue, regulatory processes have been implemented to reduce air pollution and mitigate its adverse effects. Here is a detailed overview of these regulatory processes:

Regulatory Processes to Reduce Air Pollution:

• The Clean Air Act (CAA): This landmark legislation has been in force for over 50 years and has played a pivotal role in driving pollution reduction in the United States. The CAA mandates that all areas of the country strive to meet the National Ambient Air Quality Standards (NAAQS). One key program under the CAA is the New Source Review (NSR) program, which involves a preconstruction review process for new and modified stationary sources of air pollution. The CAA also requires the U.S. Environmental Protection Agency (EPA) to regulate emissions of toxic air pollutants from industrial sources, including mercury, polychlorinated biphenyls (PCBs), benzene, and volatile organic compounds (VOCs).
• EPA Regulations and Monitoring: The EPA is responsible for monitoring air pollution levels, developing rules to address pollution, and enforcing those rules. They work collaboratively with state, local, and tribal agencies to identify areas that do not meet NAAQS standards. These areas, known as nonattainment areas, are required to implement plans to reduce air pollution and achieve compliance. The EPA also provides a list of "Best Available" air pollution control technologies and maintains databases with policy guidance documents for various regulatory topics.
• Phase-out of Leaded Gasoline: The permanent phase-out of leaded gasoline has significantly reduced airborne lead concentrations. Between 1980 and 2005, airborne lead concentrations in the U.S. decreased by 98% due to EPA's air toxics program and other national and state regulations.
• Vehicle Emission Standards and Programs: Transportation, especially private cars and motorcycles, contributes significantly to NOx emissions in cities. Various programs and standards have been implemented to address this, including inspection and maintenance (I/M) programs, vehicle retrofitting, gasoline quality improvement, and incentives for low-emission vehicles. The use of diesel particulate filters (DPF) or diesel oxidation catalysts (DOC) is also encouraged.
• Energy Source Changes: Governments have taken steps to reduce the use of solid fuels, particularly in homes, and promote the use of renewable energy, clean fuels, and alternative-fuel vehicles, such as electric vehicles.
• Incentive, Supportive, and Punitive Policies: These policies aim to reduce air pollution by encouraging or discouraging certain behaviours. For example, providing free public transportation to reduce private car usage, offering subsidies for households to switch to cleaner fuels, or implementing congestion charging for cars in certain areas.
• International Agreements: Agreements like the Paris Agreement (2015) aim to combat global warming and prevent the dangerous impacts of climate change. At the continental level, the European Union (EU) has enacted directives and guidelines for air pollutant emissions and long-range transboundary air pollution (CLRTAP).

These regulatory processes, implemented by governments and organizations worldwide, are essential steps towards reducing air pollution and safeguarding public health and the environment.

Industrial activity: a major pollutant

Industrial activity has been a major contributor to air pollution over the years. It involves the manufacturing, processing, and extraction of raw materials, which produce waste and emissions harmful to the environment and human health. Industrial pollution arises from factories, power plants, mining operations, chemical production facilities, and commercial transportation.

Power plants, particularly coal-fueled ones, emit hazardous pollutants such as PM2.5, sulfur dioxide, nitrogen oxides, and carbon monoxide. Coal-powered plants have been linked to increased mortality risks, with exposure to PM2.5 from coal associated with a mortality risk twice as high as that from all sources of PM2.5. Additionally, coal-fired plants contribute to high levels of sulfur dioxide, which, along with nitrogen dioxide, has been associated with adverse respiratory effects, increased asthma symptoms, and higher hospital admissions for respiratory illnesses.

Chemical production facilities are another source of industrial pollution, releasing fumes and hazardous chemicals into the air. Benzene, a component of gasoline, has been linked to occupational leukemia and is associated with non-Hodgkin's Lymphoma. Volatile organic compounds (VOCs), released during the combustion of gasoline and natural gas, are also emitted from chemical production processes.

Mining operations contribute to air pollution through the release of PM2.5, silica dust, coal dust, and gases like methane, carbon monoxide, sulfur dioxide, and nitrogen oxides. Heavy metals such as mercury and lead, released during mining activities, have toxic effects on human health.

Commercial transportation, including vehicles running on gasoline and diesel, emits pollutants such as PM2.5, nitrogen oxides, sulfur dioxide, carbon monoxide, VOCs, and greenhouse gases like carbon dioxide and methane.

To address industrial air pollution, the transition to cleaner fuels and industrial processes is essential. This includes adopting renewable energy sources, improving fuel efficiency, and transitioning to electric vehicles. Implementing regulations and standards, such as the EPA's federal emissions standards and the Clean Air Act, plays a crucial role in reducing industrial emissions and improving air quality.

Population exposure: health impact assessment

Air pollution is the presence of one or more contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapour, in quantities that can be harmful to human health. The main pathway of exposure from air pollution is through the respiratory tract. Breathing in these pollutants leads to inflammation, oxidative stress, immunosuppression, and mutagenicity in cells throughout the body, impacting the lungs, heart, and brain, among other organs, and ultimately leading to disease.

Population exposure to air pollution has increased over the years, with certain groups facing higher exposure to pollutants and experiencing greater adverse health impacts. These groups include people of colour, the elderly, pregnant women, children, adolescents, and those with pre-existing health conditions. Socioeconomic factors also play a role, with low-income communities and minority populations disproportionately exposed to air pollution.

Research has linked air pollution exposure to a variety of health risks and diseases. Short-term exposure to high levels of particulate matter can lead to reduced lung function, respiratory infections, and aggravated asthma. Long-term or chronic exposure increases the risk of non-communicable diseases, including stroke, heart disease, chronic obstructive pulmonary disease, and cancer. Maternal exposure to air pollution is associated with adverse birth outcomes, such as low birth weight and pre-term birth.

Fine particulate matter, such as PM2.5, is of particular concern. Exposure to PM2.5 is associated with an increased risk of premature death, with higher population exposure leading to higher numbers of premature deaths attributed to air pollution. In Europe, regions with lower GDP per capita tend to have higher levels of PM2.5, driven by the combustion of low-quality solid fuels for domestic heating.

To assess the health impact of population exposure to air pollution, researchers use various methods, including epidemiological, human observational, and toxicological studies. These studies help identify populations at greatest risk and improve risk assessments by considering modifying factors such as psychosocial stress, diet, and individual susceptibility. Electronic health records, advanced cellular models, and animal models are also employed to evaluate the health impacts and identify vulnerable populations.

Frequently asked questions