Air Pollution Standards: A Historical Perspective

Air pollution is a serious issue that poses a significant threat to human health and the environment. It is caused by a complex mixture of solid particles, liquid droplets, and gases from various sources, such as household fuel burning, industrial chimneys, traffic exhausts, and agricultural practices. To combat this issue, air pollution standards have been established by various organizations and governments. One of the earliest known air pollution standards was the Air Pollution Control Act enacted in 1959. However, the most well-known and influential air pollution legislation is the Clean Air Act, which was established in the United States in 1970 through bipartisan amendments to existing laws. This act has undergone further amendments in 1977 and 1990 to strengthen and expand its scope. The World Health Organization (WHO) has also played a crucial role in establishing global air quality guidelines, with the first release in 1987, followed by regular updates to ensure their relevance and effectiveness in reducing the health impacts of air pollution. Additionally, the European Commission has introduced new pollution rules with stricter standards to be achieved by 2030, aiming for zero pollution by 2050. These standards aim to reduce the number of premature deaths and illnesses caused by air pollution, which currently stands at 7 million premature deaths globally each year.

The Clean Air Act, 1970

Air pollution standards have existed in various forms since 1956, when the United Kingdom became the first country to adopt broad air pollution regulations. The United States followed with federal legislation to address air quality in 1955, but the Clean Air Act as we know it today largely came into existence in 1970.

The Clean Air Act of 1970 was a landmark bipartisan piece of legislation that passed unanimously in the U.S. Senate and with overwhelming support in the House of Representatives. It was signed into law by President Richard Nixon on December 31, 1970, under the banner of protecting clean air for "future generations of America."

The Act established the National Ambient Air Quality Standards (NAAQS), setting maximum allowable concentrations of six major air pollutants: carbon monoxide, lead, nitrogen oxide (NOx), ozone, particulate matter, and sulfur dioxide (SO2). It also created emissions standards for pollution sources, requiring industrial facilities to install pollution control technologies and automakers to produce cleaner, more fuel-efficient vehicles.

The Clean Air Act of 1970 shifted the focus of air quality regulation from state-oriented to federal, under the purview of the newly created Environmental Protection Agency (EPA). The EPA was tasked with overseeing the implementation of the Act and setting uniform national emissions standards for new cars and light trucks. The Act also required each state government to devise its own plan for achieving and sustaining compliance with the standards.

The Clean Air Act has been amended several times since 1970 to reflect technological advancements and an evolving understanding of safe pollutant levels. For example, the 1977 amendments addressed the problems major metropolitan areas were facing in achieving attainment with the NAAQS, especially ozone pollution standards. The 1990 amendments represented a significant expansion of air quality regulation, including provisions to establish a national permits program and control acid rain.

The Clean Air Act has had a significant impact on reducing air pollution in the United States. Since 1970, particulate air pollution has decreased by 62-64.9%, adding approximately 1.4-1.5 years to the life expectancy of the average American.

WHO Air quality guidelines

The World Health Organization's Air quality guidelines (AQG) are a set of evidence-based recommendations of limit values for specific air pollutants. The guidelines were developed to help countries achieve air quality that protects public health. While the guidelines are neither standards nor legally binding criteria, they serve as a global target for national, regional, and city governments to work towards improving their citizens' health by reducing air pollution.

The first release of the guidelines was in 1987, with several updated versions appearing since then. The latest global version was published in 2005, and the guidelines are regularly updated to assure their continued relevance and to support a broad range of policy options for air-quality management in various parts of the world. The 2021 update of the WHO air quality guidelines was in response to the real and continued threat of air pollution to public health.

The WHO Air quality guidelines recommend levels and interim targets for common air pollutants, including particulate matter (PM2.5 and PM10), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO). These pollutants can come from various sources, such as household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, and desert dust. Different sources can lead to different mixtures of air pollution. For example, an urban city near the sea may have particulate matter consisting of sea salt, road dust, and smoke from diesel engines, while a rural area near a forest may have particulate matter consisting of soil, smoke from cookstoves, and forest fire smoke.

The recommendations included in the WHO Air quality guidelines are based on systematic literature reviews, rigorous evaluation methods, and extensive consultation with experts and end-users of the guidelines from all regions of the world. The guidelines incorporate scientific evidence from multiple countries, making them relevant to diverse conditions around the world. They are intended to support a broad range of policy options for air quality management and provide guidance in reducing the health impacts of air pollution.

National Ambient Air Quality Standards

The existence of air pollution and its negative effects on human health has been acknowledged for centuries. As early as 400 BCE, Hippocrates wrote about air pollution in his work "On Airs, Waters and Places". However, it wasn't until the 18th century that government regulations and laws related to air quality began to emerge. The Smoke Abatement Act of 1273 in England, for example, aimed to curb smoke pollution by prohibiting the burning of soft coal.

In the modern era, the establishment of air pollution standards has become a crucial aspect of environmental governance. The National Ambient Air Quality Standards (NAAQS) in the United States are a prominent example of such standards. The NAAQS are health-based standards established by the United States Environmental Protection Agency (EPA) under the authority of the Clean Air Act. The Clean Air Act, last amended in 1990, mandates the EPA to set NAAQS for six principal pollutants, commonly referred to as "criteria air pollutants" or "criteria pollutants". These pollutants are widely found in outdoor air and are considered harmful to public health and the environment.

The six criteria air pollutants for which the NAAQS set limits include ozone (O3), atmospheric particulate matter (PM2.5/PM10), lead (Pb), carbon monoxide (CO), sulfur oxides (SOx), and nitrogen oxides (NOx). These pollutants are typically emitted from various sources, including industry, mining, transportation, electricity generation, and agriculture. The NAAQS establishes two types of standards: primary and secondary. The primary standards are designed to protect the health of 'sensitive' populations such as asthmatics, children, and the elderly, while the secondary standards focus on protecting the environment and addressing issues like visibility, damage to crops, vegetation, buildings, and animals.

The NAAQS are subject to periodic review and revision by the EPA. For instance, in 2010, the EPA replaced the dual primary standards with a new 1-hour standard set at 75 ppb for SO2. Additionally, the EPA has taken action to address other pollutants beyond the six criteria pollutants, such as carbon monoxide, for which the first NAAQS was set in 1971. The NAAQS, along with state, tribal, and local air agencies, play a crucial role in attaining and maintaining air quality standards throughout the United States.

EU air quality standards, 2030

The concept of air pollution and its negative health effects has been recognised for centuries. As early as 400 BCE, Hippocrates wrote about the topic in 'Airs, Waters and Places'. However, it was not until the 18th century that the existence of certain harmful substances in the air was proven, marking the beginning of air quality science. In the centuries that followed, various governments began to address air pollution concerns through regulations and laws. For example, England's Smoke Abatement Act of 1273 aimed to curb smoke pollution by prohibiting the burning of soft coal.

Fast forward to the 20th century, and air pollution became an even more pressing issue. The UK passed its first Clean Air Act in 1956 to tackle pollution and smog from coal burning. In the 1970s, the US established its first Clean Air Act, with a focus on setting national air quality standards. These early efforts laid the groundwork for the ongoing development and refinement of air pollution standards worldwide.

Today, the World Health Organization (WHO) plays a pivotal role in guiding global air quality standards. The WHO's Air Quality Guidelines (AQG) serve as a target for governments to strive towards improving the health of their citizens by reducing air pollution. While these guidelines are not legally binding, they are based on scientific evidence and offer recommended limit values for specific air pollutants.

In alignment with WHO recommendations, the European Union (EU) has been steadily tightening its air quality standards. The EU's 2030 air quality standards, which came into force on 10 December 2024, represent a significant milestone in the region's efforts to combat air pollution. The revised Ambient Air Quality Directive sets stricter standards and includes a series of new measures to ensure cleaner air for Europeans.

The 2030 EU standards focus on reducing the allowed annual limit value for fine particulate matter (PM2.5) by more than half. Additionally, they target twelve air pollutants in total, including nitrogen dioxide (NO2), nitrogen oxides (NOx), sulphur dioxide (SO2), ozone (O3), carbon monoxide, benzene, benzo(a)pyrene, arsenic, cadmium, nickel, and lead. To achieve these standards, national and local authorities will determine the necessary measures, with existing and new EU policies across various sectors contributing significantly.

While many locations in Europe already meet the 2030 standards, additional measures will likely be needed, especially in cities, to ensure compliance across the region. Regular reviews of the air quality standards will help the EU stay on track towards its zero-pollution objective for air by 2050.

Air Pollution Control Act, 1959

Federal legislation to address air quality in the US dates back to 1955, with the Air Pollution Control Act. This was the first federal legislation involving air pollution and it provided funds for federal research in this area.

The Air Pollution Control Act of 1959, Act of Jan. 8, 1960, P.L. 2119, No. 787 Cl. 35, was enacted to provide for the better protection of the health, general welfare and property of the people of the Commonwealth. This was achieved by controlling, abating, reducing and preventing pollution of the air by smokes, dusts, fumes, gases, odors, mists, vapors, pollens and similar matter, or any combination thereof. The Act imposed certain powers and duties on the Department of Environmental Resources, the Environmental Quality Board and the Environmental Hearing Board. It also established procedures for the protection of health and public safety during emergency conditions, and created a stationary air contamination source permit system.

The Act also included provisions for the Environmental Quality Board to adopt rules and regulations for the prevention, control, reduction and abatement of air pollution, applicable throughout the Commonwealth. Such rules and regulations could establish maximum allowable emission rates of air contaminants from sources, prohibit or regulate the combustion of certain fuels, prohibit or regulate open burning, and require the installation of specified control devices or equipment.

The Act also required the evaluation of motor vehicle emission control programs, including vehicle emission standards, clean alternative fuels, oxygenated fuels, reformulated fuels, vehicle miles of travel, congestion levels, transportation control measures and other transportation control strategies with respect to their effect upon air pollution. The degree of air pollution in any part of the Commonwealth was to be determined by means of field studies and sampling. A general comprehensive plan for the control and abatement of existing air pollution and air contamination, and for the abatement, control and prevention of any new air pollution, was to be prepared and developed, with varying requirements for the different areas of the Commonwealth.

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