Ozone can be good or bad for health and the environment depending on where it’s found in the atmosphere. Good ozone is stratospheric. It protects living things from ultraviolet radiation from the sun. Bad ozone is ground-level. It can trigger a variety of health concerns, particularly for children, elderly and individuals with lung diseases such as asthma.
The graphic displays the trends in eight-hour ozone design values for St. Louis and Kansas City Areas and Rural Site located at Mark Twain. The plotted values represent an average of three consecutive years of ozone monitoring data for air quality monitors in St. Louis, Kansas City and a rural site. The air quality monitor with the highest averaged value sets the ozone value for the entire area. If that value exceeds 70 parts per billion, a violation of the eight-hour ozone standard occurs. The area ozone values are plotted on the last year of the three-year period.