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Skip Navigation LinksDNREC : Division of Air Quality : ozone

Summer Air Pollution

During high ozone days, refuel your vehicle in the evening

It’s Ozone Season

If you must refuel your vehicle when ozone is expected to be high, refuel in the evening

Here’s What DNREC Is Doing:

* Monitoring air quality
* Providing daily air pollution alerts and forecasts
* Establishing additional controls as the population continues to grow in Delaware
* Cooperating with neighboring states regarding the effects of deposition on land and water.
* Working closely with EPA and other states to develop the large scale pollution prevention and control programs necessary to meet all federal Clean Air Act requirements by the year 2020.

And, here’s what you can do...

*During the spring and summer months, high temperatures and sunlight combine with pollution to form a dangerous mixture called ground-level ozone. High levels of ozone can cause health problems for many people, especially children, seniors and people with respiratory ailments.
*Check Today’s Ozone/Air Quality Forecast
(sponsored by the Air Quality Partnership of the Delaware Valley)
*Check Delaware’s current Ozone Levels at DNREC’s air monitoring stations.
*Check national and regional ozone forecasts at the U.S. Environmental Protection Agency’s Air Now website.

What Causes Ground-Level Ozone?

Ozone is a colorless gas that is the main ingredient of smog. Ground-level ozone is a severe public health concern. It damages lung tissue, aggravates respiratory conditions and makes people more susceptible to respiratory infections. Children are especially vulnerable to ozone's harmful effects. Click here for more info about ozone’s impact on health.

Ozone is formed from a chemical reaction in the lower atmosphere on hot, still, sunny days. The air pollutants contributing most to ozone formation are volatile organic compounds (VOCs) and nitrogen oxides (NOx). There are many sources of VOCs and NOx, in Delaware, including large and small industrial facilities, gasoline vapors, vehicle exhaust, chemical solvents and natural sources. Also, many of these compounds are blown in from upwind areas such as Baltimore and Washington, DC.

We’ve been measuring Delaware’s air quality for over 20 years. We are required by federal statute to monitor levels of specific pollutants on an hourly basis. Of all the pollutants that are monitored in Delaware, ozone and particulate matter occurs at levels that are classified as "unhealthy". 

The number of days with “unhealthy” levels of ozone has been declining  in the state for more than a decade. This is largely due to pollution control and prevention programs, including tougher emission controls on large industries, cleaner-running cars, vehicle emission inspection programs and reformulated gasoline.

But, ozone levels continue to be a problem in Delaware.

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