Areas of southern Montgomery County are experiencing unhealthy levels of air pollution on Thursday due to high levels of ozone, according to AirNow.gov.
The Metropolitan Washington Council of Governments announced Wednesday a forecast for a “Code Orange” air day for Thursday, warning that the air is unhealthy for “sensitive groups” such as people with heart or lung disease, older adults and children.
The council’s forecast advised that sensitive groups should make outdoor activities shorter and less intense and pay attention to ozone exposure symptoms, such as coughing or shortness of breath.
To monitor the air quality in a specific area, visit the AirNow website, which provides daily air quality reports and details about what pollutants are in the air.
Code orange air quality today. Those w/ asthma, children, elderly & outdoors workers should avoid overexertion & stay indoors.
— Montgomery Co. MD OEMHS (@ReadyMontgomery) June 12, 2025
Aire con código naranja hoy. Los con asma, niños, ancianos y las que trabajan al aire libre deben evitar el sobreesfuerzo y quédese adentro. pic.twitter.com/8xRF4wqhWE
According to the Maryland Department of the Environment, the highest levels of ozone will be centered along a corridor from Washington, D.C., through Baltimore to northeastern Maryland. The high ozone concentration stems from a combination of diffuse smoke, workweek emissions and “above normal” temperatures.
Ozone levels are likely to improve on Friday, according to the department.
“On Friday, continued warmth will keep ozone elevated but likely remaining below [unsafe for sensitive groups],” the department said in an online air quality forecast. “Presently, more tropical-like air will push into the region at the same time as a cold front approaches from the north, adding more clouds and chances for precipitation to the forecast, along with less certainty for ozone production.”
What is ozone?
Ozone at ground-level occurs when pollutants emitted by cars, power plants, industrial boilers, refineries or chemical plants chemically react in the presence of sunlight, according to the Environmental Protection Agency (EPA). Ozone, which is one of six common air pollutants, typically reaches unhealthy levels on hot, sunny days in urban environments and can even be transported by wind to rural areas.
According to the EPA, ground-level ozone can “trigger a variety of health problems” for children, the elderly and people of all ages who have lung diseases, including asthma.
Health impacts
Ozone can cause muscles in a person’s airways to constrict, causing wheezing and shortness of breath. According to the EPA, some health effects of ozone exposure include:
- Coughing and sore or scratchy throat;
- Difficulty breathing deeply;
- Inflammation and damage to airways;
- Susceptibility to lung infections;
- Aggravation of lung diseases such as asthma, emphysema and chronic bronchitis; and
- An increase in the frequency of asthma attacks.
