High temperatures and excessive heat at the end of last week kept many people indoors, but there was another reason to stay inside – ground-level ozone.
Delaware was under its third code red ozone alert for the year on July 18 with an orange alert also issued for fine particulates.
Air quality forecasts are issued throughout the summer to let the public know when air quality is unhealthy and how to take action on those days. The Delaware Valley Regional Planning Commission issues alerts on a scale of green, good; yellow, moderate; orange, unhealthy for sensitive groups; and red, unhealthy.
“It’s when things get stagnant that pollutants build up, which is what is happening now,” said David Fees, Air Quality Management program manger within the Department of Natural Resources and Environmental Control, in a July 17 interview.
State climatologist David Legates said any kind of air movement, whether a horizontal wind or thunderstorms, which create vertical movement, can help break up pollutants.
Although many know more about the high altitude ozone that protects the Earth from the sun, people do have the understanding that ozone, or smog as it’s sometimes called, in the summer is a bad thing, Fees said. It forms in heat and sunlight when oxygen reacts with pollutants that originate from automobiles, power plants, construction equipment, farm tractors, or solvents in paint or gasoline.
Going hand in hand with ozone pollution are fine particulates, which can combine for a hazy look, he said. The particulates in the air, which get a separate air quality forecast issued throughout the entire year, are found in smoke and haze and can come from forest fires or form from gases emitted from power plants, industries and automobiles, according the Environmental Protection Agency.
When levels of either pollutant become too high, they pose a danger because they act as lung irritants, Fees said. According to the EPA, health problems that can develop are chest pain, coughing, throat irritation and congestion. Bronchitis, emphysema and asthma conditions also may be worsened.
On red alert days all people are encouraged to stay indoors, although the best time to be outside is in the morning, Fees said, as the pollutants tend to build throughout the day and peak at approximately 3 to 6 p.m. before tailing off when the sun goes down. People also can limit activities that contribute to air pollution such as refueling their car in the morning before going to work or mowing the lawn.
