Summer officially begins on June 21--the longest day of the year--and the
Indiana Department of Environmental Management (IDEM) wants to remind
Hoosiers that longer days mean more energy from the sun beating down on the
“That energy from sunlight mixes with emissions from vehicles and industrial
plants, producing ozone in our lower atmosphere,” IDEM says. “While ozone
high in the stratosphere protects us from the sun’s harmful ultra-violet
(UV) rays, when ozone is created down where we live, it can make breathing
difficult for some people.”
As weather forecasts point to conditions favorable for the accumulation of
this ozone, IDEM will issue “air quality action days” over the course of the
An air quality action day is declared when IDEM’s meteorologists have looked
at weather patterns, cloud forecasts, and other data to determine that a
certain period of time will likely see higher ozone levels than normal for a
Whenever there is an air quality action day for your area, doing the
following will reduce the chance that the air you breathe will become
* Drive only when necessary. Fewer vehicle emissions in the air mean fewer
compounds that can turn into ozone when the sun’s heat bakes down on them.
Instead of driving. So walk, ride your bike, or just lounge around at home.
If you have to work that day, take the bus in or carpool. If you live close
to your job, think about walking or biking to work. That way you can stay
healthy, while reducing air pollution.
* Fuel your vehicle after 7 p.m. When you gas up your car, vapors that
escape can react with the sun to produce ozone. After 7 p.m., there is less
energy in the atmosphere to create this reaction.
* Mow your lawn after 7 p.m. as well. Even though your lawn mower’s motor is
likely smaller than your car’s, it has a less sophisticated emissions
control system, so it probably pollutes more than a modern automobile does.
* Don’t idle your vehicle. Instead of using the drive-through lane, park
your car and go inside to pick up your food.
Air quality action days are also called if fine particulate matter (PM 2.5)
is at levels that can interfere with some people’s health. These tiny
particles are the result of vehicle emissions, burning coal or wood, and
some industrial processes. PM 2.5 refers to the size of the particles which
are 2.5 microns in width or smaller. These particles create a hazy, foggy
cloud over an area.
Like ozone, the prevalence of PM 2.5 is closely tied to the weather
forecast. IDEM meteorologists look especially at wind patterns and
temperature changes to determine if PM 2.5 levels are likely to be high for
a certain day. Hot days with stagnant air are more likely to become air
quality action days. The same methods of preventing ozone help to prevent an
increase of PM 2.5 in the air as well.
SmogWatch is an informational online tool created by IDEM to share air
quality forecasts for each day. It provides daily information about
ground-level ozone and particulate matter air quality forecasts, health
information, and monitoring data for seven regions of Indiana. You can find