Summer heat brings Air Quality Action Days

Watch for “orange” and “red” days

When temperatures rise, air quality may decrease, thanks to ground-level ozone, the most widespread pollutant in the U.S. Because ozone formation is influenced by the weather, it is possible to predict high ozone pollution days, which are referred to as “Air Quality Action Days.”

“Orange” and “Red” Air Quality Action Days

The Air Quality Index or AQI, available at, releases daily information about clean or polluted outdoor air within a region and identifies health issues that may be affected.

The AQI runs from 0 to 500, and according to the Environmental Protection Agency, or EPA, values below 100 are generally considered satisfactory. When AQI values are above 100, air quality is considered to be unhealthy–initially affecting certain sensitive groups, then including everyone as AQI values increase.

Air Quality Action Days, previously called “Ozone Action Days,” are designated when the AQI gets into unhealthy ranges. “Orange” levels, range from 101-150, and especially affect sensitive groups, such as people with lung disease, seniors, children, teenagers and people who are active outdoors.

According to the EPA, people who are sensitive to ozone should reduce prolonged outdoor activities, and should watch for symptoms including coughing or shortness of breath.

“Red” levels, which range from 151-200, affect everyone, according to the EPA. Sensitive groups should avoid prolonged or heavy outdoor exertion, and schedule outdoor activities when ozone is lower. Everyone else should reduce prolonged or heavy outdoor exercise and take more breaks from the heat.

“Exposure to ozone can make the lungs more susceptible to infection, aggravate lung diseases, increase the frequency of asthma attacks and increase the risk of early death from heart or lung disease,” according to the EPA.

The APG Air Quality Program Manager Dr. Hazoor Khan, said that “purple” levels, which range from 201-300, and “maroon” levels, which range from 301-500, are rare in Maryland.

Air Quality Action Days at APG

As a public service, the APG Directorate of Public Works, or DPW, Environmental Division displays Air Quality Action Day flags near the APG North (Aberdeen) entrance gates, when the AQI reaches orange levels and higher.

Fuel stations close Action Days

Filling up a vehicle’s gasoline tank releases volatile organic compounds, or VOCs into the air, adding to the smog levels. At APG, government fuel stations close during the peak hours of 9 a.m. to 3 p.m. on “Orange” Action Days and higher.

“Try to carpool or save energy in general because any gasoline use is going to increase the ground level ozone,” said Aasim H. Cheema, an  Oak Ridge Institute for Science and Education Air Quality associate, with the DPW Environmental Division. “We are going to see more of these action days popping up in the summer.”

Taking action

According to the American Lung Association’s State of the Air 2016 report, there are two types of air pollution that dominate in the U.S., ozone and particle pollutions.

“Thanks to the Clean Air Act, the U.S. has far less of both pollutants now than in the past. Still, more than 166 million people live in counties where monitors show unhealthy levels of one or both—meaning the air a family breathes could shorten life or cause lung cancer,” the report states.

According to the EPA, people can help reduce ozone by:

  • Turning off lights when they are not in use
  • Carpooling, using public transportation, and biking or walking when possible
  • Keeping vehicles well tuned
  • Inflating tires to the recommended pressure
  •  Using low-VOC paint and cleaning products, and sealing tightly when not in use to prevent evaporation.

Khan recommends subscribing to EnviroFlash emails or downloading free #BreathEasy mobile applications for more information. Both provide up-to-date air quality information and Action Day alerts. These tools are found on

For more information about the Air Quality Action Day program at APG, contact Khan at 410-306-2278, or email