Compared to Distribution

an indicator guage with the arrow in the green the value is in the best half of communities.

an indicator guage with the arrow in the yellow the value is in the 2nd worst quarter of communities.

an indicator guage with the arrow in the red the value is in the worst quarter of communities.

Compared to Target

green circle with white tick inside it meets target; red circle with white cross inside it does not meet target.

Compared to a Single Value

green diamond with downward arrow inside it lower than the comparison value; red diamond with downward arrow inside it higher than the comparison value; blue diamond with downward arrow inside it not statistically different from comparison value.

Trend

green square outline with upward trending arrow inside it green square outline with downward trending arrow inside it non-significant change over time; green square with upward trending arrow inside it green square with downward trending arrow inside it significant change over time; blue square with equals sign no change over time.

Compared to Prior Value

green triangle with upward trending arrow inside it higher than the previous measurement period; green triangle with downward trending arrow inside it lower than the previous measurement period; blue equals sign no statistically different change from previous measurement period.

green chart bars Significantly better than the overall value

red chart bars Significantly worse than the overall value

light blue chart bars No significant difference with the overall value

gray chart bars No data on significance available

Annual Ozone Air Quality

Select a County

Measurement Period: 2020-2022

This indicator gives a grade to each county in the U.S. based on the annual number of high ozone days.

Why is this important?

While ozone is an important shield against ultraviolet rays in the Earth's upper atmosphere, it is a pollutant that can cause health problems at ground level. Ground-level ozone is formed when volatile organic compounds (VOCs) and nitrogen oxides (NOx) react in sunlight; both of these pollutants are found in emissions from vehicles, motorized equipment, factories, and some consumer products. Ozone primarily affects the respiratory tract, causing breathing difficulties, aggravating existing lung diseases, and inflaming lung tissue. Although everyone is susceptible to ozone's effects, children, people with lung disease, and older adults tend to be more sensitive to ozone.

More...