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Your Environment. Your Health.

Air Pollution


Air Pollution

smoke billowing from the smoke stacks

Air pollution is a mixture of natural and man-made substances in the air we breathe.  It is typically separated into two categories: outdoor air pollution and indoor air pollution.

Outdoor air pollution involves exposures that take place outside of the built environment. Examples include:

  • Fine particles produced by the burning of fossil fuels (i.e. the coal and petroleum used in traffic and energy production)
  • Noxious gases (sulfur dioxide, nitrogen oxides, carbon monoxide, chemical vapors, etc.)
  • Ground-level ozone (a reactive form of oxygen and a primary component of urban smog)
  • Tobacco smoke
Indoor air pollution involves exposures to particulates, carbon oxides, and other pollutants carried by indoor air or dust. Examples include:
  • Gases (carbon monoxide, radon, etc.)
  • Household products and chemicals
  • Building materials (asbestos, formaldehyde, lead, etc.)
  • Outdoor indoor allergens (cockroach and mouse dropping, etc.)
  • Tobacco smoke
  • Mold and pollen

In some instances, outdoor air pollution can make its way indoors by way of open windows, doors, ventilation, etc.

What health effects are linked to air pollution?

Over the past 30 years, researchers have unearthed a wide array of health effects which are believed to be associated with air pollution exposure.  Among them are respiratory diseases (including asthma and changes in lung function), cardiovascular diseases, adverse pregnancy outcomes (such as preterm birth), and even death.

In 2013, the World Health Organization concluded that outdoor air pollution is carcinogenic to humans.

How can I reduce my risk for air pollution exposure?

Indoor air pollution can be reduced by making sure that a building is well-ventilated and cleaned regularly to prevent the buildup of agents like dust and mold.  Occupants would also be wise to remove any known pollutants and or irritants (aerosols, stringent cleaning supplies, etc.) whenever possible.

Outdoor air pollution exposures can be reduced by checking one’s Air Quality Index (AQI), avoiding heavy traffic when possible, and avoiding secondhand tobacco smoke.

How is air pollution linked to climate change?

While climate change is a global process, it has very local impacts that can profoundly affect communities, not the least of which is air pollution.

Increasing temperatures are directly linked to poor air quality which, in turn, can affect the heart and exacerbate cardiovascular disease.  Examples of this may include a rise in pollen, due to increased plant growth, or a rise in molds, due to severe storms — both of which can worsen allergies and other lung diseases, such as asthma.

Scientists say an increasing rise in ozone levels are also a concern.

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Impacts of Climate Change on Human Health in the United States: A Scientific Assessment

Impacts of Climate Change on Human Health in the United States: A Scientific Assessment

Climate change is affecting the health of Americans. As the climate continues to change, the risks to human health will grow, exacerbating existing health threats and creating new public health challenges. This assessment significantly advances what we know about the impacts of climate change on public health, and the confidence with which we know it. While all Americans will be affected by climate change, the report recognizes populations of concern, such as children, the elderly, outdoor workers, and those living in disadvantaged communities, who are disproportionately vulnerable.

Read the full report online
Video: Impacts of Climate Change on Human Health in the United States: A Scientific Assessment

Effects of Climate Change on Children's Health: Session Two: Air Quality Impacts

MODERATOR: Susan Anenberg, EPA

Meredith McCormack, Johns Hopkins University
• Effects of Climate Change on Children’s Health: Air Quality Impacts

Frederica Perera, Columbia University
• Air quality Impacts of Fossil Fuel Combustion and Climate Change on Children’s Health: Evidence from New York City

Effects of Climate Change on Children's Health



Content courtesy of the US Centers for Disease Control and Prevention (CDC)

What NIEHS is Doing on Air Pollution 

Who We Fund

For more information on NIEHS researchers doing work in this area, please visit our website’s Who We Fund page.

The NIEHS-supported Harvard Six Cities Study is a landmark research project in that it was one of the first studies in history to show that air pollution was associated with increased risks of mortality.  This study helped in the establishment of some of the national air quality standards that exist today.

Additional examples of NIEHS’ involvement in air pollution research and monitoring tools are as follows: 

My Air, My Health Challenge

In June of 2012, NIEHS helped kick off the My Air, My Health Challenge, a year-long competition among tech-savvy innovators to develop a personal, portable air pollution sensor that would measure both air pollution and the physiological responses of the individual being exposed to it.  The project came to a close in June 2013 when the company, Conscious Clothing, was awarded the My Air grand prize of $100,000 for its proposed design and product development plan.

The My Health, M y Air Challenge was a joint project between NIEHS, the National Institutes of Health, the U.S. Department of Health and Human Services, and the U.S. Environmental Protection Agency.

Related stories from the Environmental Factor:

NIEHS Cookstove Program

Over the past eight years NIEHS has invested some $9 million in research related to cookstoves and their health effects.  This has occurred primarily through community-based intervention studies in Guatemala, Ecuador, Nepal, Pakistan, Ghana, and the U.S. with study endpoints including lower respiratory infection and tuberculosis in children, low birth weight, COPD, and other respiratory conditions in adult women.

More information on the NIEHS cookstove program is available online.

The Mexico Childhood Asthma Study

The Mexico Childhood Asthma Study is a case-parent triad study of childhood asthma in Mexico City, home to the highest ozone levels in North America. Funded by NIEHS, the study’s emphasis is on candidate genes that may be involved in ozone response.

Additional information about The Mexico Childhood Asthma Study is available online via the program’s page on this website.

The Centers for Children’s Environmental Health and Disease Prevention Research

NIEHS has partnered with the U.S. Environmental Protection Agency to support research centers devoted exclusively to children’s environmental health and disease prevention. These centers utilize the expertise and resources of top universities and medical centers to focus on the important role that environmental toxicants, including air pollution, play in the development of many childhood illnesses.

Stories from the Environmental Factor

Partnerships for Environmental Public Health Podcasts

Other NIEHS programs, projects, and initiatives

General Information 

  • - A service from the U.S. Environmental Protection Agency that offers daily Air Quality Index updates for more than 400 cities.
  • Indoor Air Pollution  - A compilation of links from the U.S. Department of Health and Human Services (HHS) to government and non-government websites covering specific environmental, biological, and chemical agents that cause indoor air pollution.
  • Outdoor Air Pollution  - A compilation of links from HHS to government and non-government websites covering specific environmental, biological, and chemical agents that cause outdoor air pollution.

Related Topics 

Related Resources 

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