Smog is a term used to describe air pollution that is a result of the interaction of sunlight with certain chemicals in the atmosphere. The two primary pollutants in smog are ground-level ozone (O3) and particulate matter (PM).
These pollutants come from a variety of sources, including:
Automobiles, trucks and buses; large industry and combustion sources such as utilities; small industry such as gasoline dispensing facilities and print shops; consumer products such as paints and cleaners; off-road engines such as aircraft, locomotives, construction equipment and lawn and garden equipment.
Ozone is a colorless gas that can be found in the air we breathe. Ozone exists naturally in the earth's upper atmosphere, known as the stratosphere, where it shields the earth from the sun's ultraviolet rays. However, ozone is also found close to the earth's surface. This ground-level ozone, because we breathe it, is a harmful air pollutant.
Ground-level ozone affects everyone, but children and the elderly are especially at risk. Ozone makes it difficult for lungs to absorb oxygen, limiting the body's ability to breathe. It irritates the mucous lining of the throat and lungs, causing coughing and even choking. People with asthma, bronchitis and other respiratory problems experience more severe symptoms.
PM (dust, soot, ash and other solids and aerosols) can come from a variety of sources, including wood burning, diesel engines, gasoline engines, factories and power plants. Individually, these particles and droplets are invisible to the naked eye, but collectively, they can appear as clouds or a fog-like haze.
PM can penetrate into sensitive regions of the respiratory tract and even transfer into the bloodstream. Smaller particles can cause persistent coughs, phlegm, wheezing and physical discomfort.
A Smog Alert is issued by the Southwest Ohio Air Quality Agency (Agency) between 2:00 p.m. and 2:30 p.m. the day before high ozone and/or high particulate matter levels are anticipated.
Each morning, beginning April 1 through October 31, staff members retrieve and review data and weather forecast information. If unhealthy levels of ozone or particulate matter are expected, a conference call is scheduled by the Agency, in cooperation with local meteorologists and the National Weather Service, to determine if conditions are favorable to issue a smog alert. If the data indicates that ozone or particulate matter may meet or exceed National Ambient Air Quality Standards, a Smog Alert is issued.
Smog Alerts may soon become a problem in the winter, not just the summer. Recent adjustments to federal regulations have tightened the PM standard, increasing the possibility for Winter Smog Alerts issued due to high PM levels. Wintertime open burning and warming up cars, combined with weather inversions, can make PM-based Winter Smog Alerts a reality for Southwest Ohio residents.
On March 12, 2008, the U.S. EPA announced its most stringent standard for ozone. The new standard will lower the allowable concentration of ozone in the air to no more than .075 parts per million, compared to the old standard of .08 parts per million.
The Agency hopes that every resident in the four county area will make some small change in his or her daily habits on Smog Alert days to reduce smog formation. Your actions can make a difference in our community.