Ozone a Key Contributor to Pollution in Tehran

High concentrations of ozone near ground level along with dust particles will diminish the capital's air quality over the coming summer days, officials at Air Quality Control Company have forecast.  
Besides ozone, which occurs naturally in the earth's upper atmosphere, forming a protective layer that shields the earth from the sun's harmful ultraviolet rays, there is "bad" ozone in the earth's lower atmosphere, near ground level, which is considered a harmful air pollutant.
"The ground level ozone is a secondary pollutant, formed when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants and other sources react chemically in the presence of sunlight," ISNA quoted Hossein Shahbazi, director of modeling and forecast at Tehran's AQCC as saying.