An Orange Alert for poor air quality has been issued in the Washington DC metro for June 27 and 28. (Shutterstock)
WASHINGTON, DC — Authorities have declared an air quality alert of "orange" for the Washington, D.C. region on Thursday, June 27, and Friday, June 28, because of elevated ozone levels. An orange alert means "unhealthy for sensitive groups," according to the Environmental Protection Agency.
"Think of the AQI as a yardstick that runs from 0 to 500," the EPA says on its website. "The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 represents good air quality with little potential to affect public health, while an AQI value over 300 represents hazardous air quality. … When AQI values are above 100, air quality is considered to be unhealthy-at first for certain sensitive groups of people, then for everyone as AQI values get higher."
Orange level would put the air quality between 101 and 150.
The Air Quality Index (AQI) is based on five criteria pollutants that are regulated under the Clean Air Act: ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide and nitrogen dioxide.
Those who have sensitive medical conditions are encouraged to stay indoors.
Although general public is not likely to be affected at this level, people with lung disease, older adults and children are at a greater risk from exposure to ozone, whereas persons with heart and lung disease, older adults and children are at greater risk from the presence of particles in the air.
The air quality index drops to moderate pollution on Saturday, June 29, when air quality may pose a moderate health risk, especially for those who are unusually sensitive to air pollution.
Winds will turn southerly Monday as high pressure slides off the Mid-Atlantic coast. … Good air quality is expected to continue thanks to a very clean residual air mass and increased afternoon cloudiness, says the Metropolitan Washington Council of Governments in its alert.
"Temperatures will remain warm Tuesday and Wednesday as high pressure begins to build to our south. Ozone levels will likely increase Tuesday but will stay in check thanks to blustery surface winds. Generally low moderate AQI values expected. Winds will be a bit weaker Wednesday as plentiful sunshine and continued warmth help to push ozone levels well into the Moderate range for most of the state," says the Maryland Department of the Environment.
Here’s the upcoming weekend forecast for DC and northern Virginia from the National Weather Service:
Thursday: Sunny, with a high near 93. Calm wind becoming northwest around 6 mph in the afternoon.
Thursday Night: Partly cloudy, with a low around 76. Northwest wind around 5 mph becoming calm in the evening.
Friday: Isolated showers and thunderstorms after 3pm. Mostly sunny, with a high near 94. Light and variable wind becoming south around 5 mph in the afternoon. Chance of precipitation is 20%.
Friday Night: Isolated showers and thunderstorms before 11pm. Partly cloudy, with a low around 76. South wind around 5 mph becoming calm after midnight. Chance of precipitation is 20%.
Saturday: A slight chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 95. Light west wind increasing to 6 to 11 mph in the morning. Chance of precipitation is 20%.
Saturday Night: A chance of showers and thunderstorms between 8pm and 2am, then a slight chance of showers. Partly cloudy, with a low around 78. Chance of precipitation is 30%.
Sunday: A chance of showers and thunderstorms after 8am. Mostly sunny, with a high near 91. Chance of precipitation is 30%.
Sunday Night: Partly cloudy, with a low around 70.