Ozone is the only air pollutant monitored that is a secondary source
pollutant, a product not directly emitted. Ozone is a resultant product of a
series of chemical reactions in the atmosphere involving sunlight, oxides of
nitrogen, and volatile organic compounds. High temperatures and stagnant wind
patterns contribute greatly to the formation of ozone and thus smog. Ozone
not only contributes to smog and an increased greenhouse effect but it also
prevents harmful ultra-violet light rays from penetrating the earth's upper
The National Ambient Air Quality Standards (NAAQS) for ozone, as of
June 2011, is 75 ppb (parts per billion) based on an average of the 4th
highest eight hour average values over a three year period. The standard is
currently being considered for revision (7/2011). The EPA only requires that
ozone be monitored for the time period of April 1 to October 31 each year.
The reason for this time frame is that certain meteorological criteria,
typically not present in the winter months in Ohio, must be present for the
formation of ozone to occur.
ARAQMD monitors ozone at three
sites: Patterson Park, Medina, and Lake Rockwell.
in depth information about ozone is
available through the EPA including basic information, health and
environment, standards, designations, implementation, regulatory actions, trends,
sources, early action compacts, and other resources.