With the arrival of summer, bothersome air pollutants will begin to cause major problems throughout several major U.S. cities.

In addition to the well-known haze and smog, bad air quality can cause respiratory and heart problems, as well as aggravating asthma. Children, the elderly and people with heart disease are even more vulnerable to air pollution.

There are five big pollutants that affect air quality throughout the U.S. All of these pollutants - - ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide, and nitrogen dioxide- - become more prevalent in summer, reaching dangerous levels during hot and sunny weather when winds that would normally mix the atmosphere remain light.

Many of these pollutants enter the atmosphere by the mostly-efficient burning of fossil fuels - - gasoline, diesel, coal, and wood - - by cars, trucks, locomotives, boats, construction vehicles, power plants and industries. Additional pollution comes from the release or evaporation of organic chemicals from consumer products such as paints, cleaners and the filling of gas tanks.

These pollutants, in presences of each other and sunlight, form the smog that can irritate and cause major health problems.

To help Americans prepare for the summer air quality problems, the EPA is once again issuing an air quality forecast for most major cities in the U.S. This forecast will utilize the Air Quality Index (AQI) which is a six-level scale with categories running from healthy to unhealthy.

The most up-to-date AQI for your area is available in WeatherBug`s Outdoor Health section. Click here for the EPA`s full explanation of the AQI.

Source: Environmental Protection Agency

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