How does stratospheric ozone form

In particular, ozone can harm sensitive vegetation during the growing season. Learn more about how ozone harms ecosystems. Air quality forecasts are often given with weather forecasts on handheld devices, online or in the paper or television. You can check ozone levels and other daily air quality information by visiting www. There are actions every one of us can take to reduce air pollution and keep the air cleaner and precautionary measures you can take to protect your health.

Visit AIRNow for tips on what you can do. Ozone is one of the six common air pollutants identified in the Clean Air Act. These standards apply to the concentration of a pollutant in outdoor air. After working with the states and tribes and considering the information from air quality monitors, EPA "designates" an area as attainment or nonattainment with national ambient air quality standards.

If the air quality in a geographic area meets or does better than the national standard, it is called an attainment area; areas that don't meet the national standard are called nonattainment areas. Learn more about ozone air quality designations. In order to improve air quality, states must draft a plan known as a state implementation plan SIP to improve the air quality in nonattainment areas.

The plan outlines the measures that the state will take in order to improve air quality. Thursday, Nov. State offices will reopen Friday, Nov. Reporting will resume on Friday, Nov. Ozone is a molecule made up of three oxygen atoms, often referenced as O 3. This reaction can occur both near the ground and high in the atmosphere. Stratospheric ozone is good ozone. Tropospheric or ground-level ozone — what we breathe — is formed primarily from photochemical reactions between two major classes of air pollutants, volatile organic compounds VOC and nitrogen oxides NOx.

These reactions have traditionally been viewed as depending upon the presence of heat and sunlight, resulting in higher ambient ozone concentrations in summer months.

Within the last decade, however, high ozone concentrations have also been observed under specific circumstances in cold months, where a few high elevation areas in the Western U. Ozone contributes to what we typically experience as "smog" or haze, which still occurs most frequently in the summertime, but can occur throughout the year in some southern and mountain regions.

Although some stratospheric ozone is transported into the troposphere, and some VOC and NOx occur naturally, the majority of ground-level ozone is the result of reactions of man-made VOC and NOx. Significant sources of VOC are chemical plants, gasoline pumps, oil-based paints, autobody shops, and print shops. Nitrogen oxides result primarily from high temperature combustion.

Significant sources are power plants, industrial furnaces and boilers, and motor vehicles. Many people mistakenly believe that tropospheric ozone concentrations are high only in major urban areas, but high ambient ozone concentrations can and do occur anywhere.

It is also formed in smaller cities like Raleigh, NC and Cincinnati, OH, and it is transported hundreds of miles downwind from where it is created to affect ambient air quality in other urban and rural areas.

Where ozone is formed, peak concentrations usually occur during afternoon hours, when sunlight is the most intense. However, areas downwind of major sources of VOC and NOx may experience ozone peaks in the afternoon and evening, after wind has carried ozone and its VOC and NOx precursors many miles from their sources.

Thus, high ozone concentrations can occur in remote areas and at various times of day, including during the early evening or night.