Air Pollution and Community Health

Learn about the public health effects of air pollution.

Air Pollution and Public Health

Scientific research has demonstrated the negative impact of air pollution on health. Air pollution has been linked with disease or damage to the lungs in the form of asthma, bronchitis, and emphysema. There is also increasing evidence that air pollution contributes to heart attacks and strokes, diabetes, and dementia.

The relationship between air pollution and public health can be expressed in terms of:

Emissions - Concentrations - Exposure - Dosage - Health Effects


In the Bay Area, many different sources emit a wide variety of air pollutants, such as particulate matter, toxic air contaminants, and other chemicals that react in the atmosphere to form ozone. Emission sources include stationary sources like factories, refineries, foundries, and gas stations, and mobile sources such as cars, trucks, trains, marine vessels, and farm and construction equipment.

Identifying the emission sources and developing strategies to reduce emissions of harmful pollutants, or their chemical precursors, is the first step in developing measures to reduce air pollution and improve air quality. The Air District develops emissions inventories to characterize and quantify emissions of key pollutants.


Ambient concentrations refers to the level of pollutants that are measured in the air. The relationship between emissions and ambient concentrations is complex and depends upon many factors, including meteorological conditions (temperature, wind speed and direction, and vertical mixing) the ratio of pollutants (e.g., the ROG to NOx ratio, in the case of ozone), and topography.

Some pollutants such as ozone are regional in scale. In the case of particulate matter and toxic air contaminants, however, ambient concentrations can vary greatly within a small geographical area.

The Air District uses its ambient air monitoring network to measure air pollutant concentrations and performs photochemical modeling to better understand the relationship between emissions and ambient concentrations.


Exposure refers to the amount of pollution that a given individual or community is exposed to, and the frequency and duration of that exposure.

From the public health perspective, the key issue is not how much pollution is present in the air, but rather how many people are exposed to the pollution. Individual exposure to air pollution varies greatly depending upon where people live, work, and play. Total population exposure is greater in urban areas due to higher population density.


Dosage refers to the actual amount of pollution that an individual takes into the body. The dosage from a given level of exposure will vary by individual depending upon age, activity, and metabolic rate.

For example, when people are exercising, especially children, they receive higher dosages from a given amount of exposure because they are breathing deeper and faster. Activity patterns and lifestyle, such as how much time people are outside, or how much time they spend driving on busy roadways, vary greatly from person to person.

Health Effects

Air pollution can cause or contribute to a wide range of health effects and illnesses, depending upon individual exposure and tolerance to air pollution. Just as individual exposure differs, so does the ability of our bodies to tolerate exposure to pollutants.

The Air District is especially concerned about reducing population exposure for people who are most vulnerable to air pollution, including children, pregnant women, seniors, and people with existing cardiovascular or respiratory conditions.

Low-income, predominately minority communities are also particularly vulnerable to the effects of air pollution, due to limited access to health care and social, economic, and environmental stressors, which increase health vulnerabilities.

Spare the Air Status

Last Updated: 10/4/2018