Air Quality

The EPA has concluded that there is compelling evidence that many fundamental measures of climate in the United States (e.g., air temperature) are changing, and many of these changes are linked to the accumulation of greenhouse gases (GHG’s) in the atmosphere. GHG emissions from the U.S. have increased by approximately 7 percent since 1990 and global GHG emissions are increasing at an even greater rate. Among other impacts, climate change also contributes to worsening air quality that can endanger public health.

The Air Quality Index (AQI) is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air.

EPA calculates the AQI for five major air pollutants regulated by the Clean Air Act: ground level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide. For each of these pollutants, EPA has established national air quality standards to protect public health.


Baltimore’s air quality index is 0.3% greater than the Maryland average and 8.1% greater than the national average.  The Baltimore, MD pollution index is the sum of the most hazardous air pollutants displayed in pounds. Baltimore’s pollution index is 35.4% greater than the Maryland average and 48.3% greater than the national average.


Weather has a major influence on the spreading and surrounding concentrations of air pollutants. Large high-pressure systems often alter the normal temperature profile, trapping pollutants at the Earth’s surface. Increased summer temperatures will lead to an increase in air pollution concentrations in cities, including Baltimore.

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