History of Air Pollution

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EPA's Air, Climate, and Energy Research is at the forefront of air pollution research to protect public health and the environment. The research is providing the scientific foundation for the U.S. Environmental Protection Agency, states and communities to make decisions to effectively reduce and control air pollution.


In October 1948, Donora, Pa., was enveloped in a lethal haze.

Over five days, nearly half of the town's 14,000 residents experienced severe respiratory and cardiovascular problems. It was difficult to breathe. The death toll rose to nearly 40.

Disturbing photos show Donora's streets hidden under a thick blanket of gray smog. A warm air pocket had passed high above the town, trapping cooler air below and sealing in pollutants.

Donora was no stranger to pollution. Steel and zinc smelters had long plagued the town with dirty air. But the air pocket left pollutants with no escape route. They sat stewing in the streets, where residents breathed them in lethal doses.

The situation in Donora was extreme, but it reflected a trend. Air pollution had become a harsh consequence of industrial growth across the country and world.

Crises like Donora's were widely publicized; people took notice and began to act.

Scientists started investigating the link between air pollution and health. States began passing legislation to reduce air pollution. And in 1970, a milestone year, Congress passed the Clean Air Act Amendments which led to the establishment of the nation's air quality standards.

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Today, policymakers and air quality managers rely on cutting-edge science to establish regulations and make management decisions to reduce and control air pollution with cost-effective approaches.

EPA's Air, Climate, and Energy Research conducts a vast amount of this research, producing findings and developing technology vital to our understanding of air pollution. For the most common pollutants, the research is compiled and synthesized every five years by EPA scientists to assess the adequacy of air regulations.

EPA seeks to identify specific chemicals as well as specific sources (like cars, trucks and power plants) that can impact air quality. A major goal is to pinpoint the sources most responsible for health risks.

For example, EPA studies have shown that tiny particles released when gas, oil and other fossil fuels are burned harm the respiratory and cardiovascular systems. We now know that these particles are especially harmful to the most vulnerable populations: the young, older adults and those with pre-existing health conditions.

The research program provides an innovative and interdisciplinary approach to the air pollution problem. Renowned EPA scientists, engineers and physicians work together and partner with scientific experts across the United States and worldwide to address the many challenges of air quality management.

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Car Emissions

Future Directions

Major strides have been made to improve air quality, but many complex scientific questions remain, calling for innovative and novel research.

It has become increasingly clear that multiple pollutants play a role in determining risks to people and the environment. EPA is moving forward with a "multipollutant" approach to air pollution research. It is crucial to understand the collective impacts of multiple air pollutants, how they interact in the atmosphere and whether the interactions modify health effects.

EPA's Air, Climate, and Energy Research has already spearheaded interdisciplinary efforts to study combinations of multiple pollutants more extensively. An important series of studies has begun near major, high traffic roads where people, live, work and go to school.

Recent studies have identified respiratory and cardiac effects, cancer and even mortality as risks for populations living near major roads. These initial reports raise concerns about building schools and other facilities near roadways. They also call into question the quality of indoor air in buildings near roadways and underscore the need to understand the general health impacts on people living near traffic.

EPA is also pursuing an understanding of how climate change and air quality interact and the consequences for public health and the environment. EPA scientists have already provided evidence that future temperature increases will increase air pollution levels in some regions of the country. What's more, urban areas already suffering from pollution problems may incur the greatest burden of these changes.

EPA will continue investigations of how climate change will impact the air we breathe, with a focus on protecting current and future generations from air pollution health risks.

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