Particulate matter is the term used for a mixture of solid particles and liquid
droplets found in the air. Coarse particles (larger than 2.5 micrometers) come from
a variety of sources including windblown dust and grinding operations. Fine particles
(less than 2.5 micrometers) often come from fuel combustion, power plants, and diesel
buses and trucks.
Ozone is a major
element of urban smog. Ozone can limit the ability to take a deep breath,
and it can cause coughing, throat irritation, and breathing discomfort.
There is also evidence that ozone can lower resistance to respiratory
disease (such as pneumonia), damage lung tissue, and aggravate chronic
lung disease (such as asthma or bronchitis).
The ozone season
for the U.S. begins May 1st. However, some states including Iowa begin
the ozone season April 1st. Ozone maps are currently available for Iowa.