Ozone Action Days

Do Your Share For Cleaner Air

Air Quality Forecast and Action Guide

	Air Quality	Weather Conditions	Recommended Actions
Code Red	Unhealthful	Hot (middle 90s to 100s) hazy and humid Stagnant air, little or no wind Little chance of rain Stationary high pressure system with sunny skies	*When air quality reaches unhealthful levels:* Children and elderly individuals should reduce outdoor activities. Healthy individuals should limit strenuous outdoor work or exercise. Individuals with heart or respiratory ailments, emphysema, asthma, or chronic bronchitis should limit their outdoor activities. If breathing becomes difficult, move indoors. *When air quality is forecast to reach unhealthful levels, residents are strongly urged to:* Limit driving and, when possible, combine errands. Use area bus and rail lines, or share a ride to work. Avoid mowing lawns with gasoline powered mowers. Refuel cars after dusk. Listen for air quality updates.
Code Orange	Approaching Unhealthful	Temperatures in the upper 80s to low 90s Light Winds Slow moving high pressure system with sunny skies	*When air quality approaches unhealthful levels, residents are urged to:* Refuel cars after dusk to limit daytime pollution releases. Avoid mowing lawns with gasoline powered mowers. Share a ride or drive only their newest, best maintained vehicle.
Code Yellow	Moderate	Mild summer temperatures (upper 70s to mid 80s) Light to moderate winds (15 knots or less) High pressure system with partly cloudy or sunny skies	*When air quality is in the moderate range, residents should:* Consolidate trips and errands. Limit idling when possible. Conserve electricity and set air conditioners to 78°F.
Code Green	Good	Cool summer temperatures (mid 70s to low 80s) Windy conditions (15-20 knots or higher) Heavy or steady rain Passing cold front carries pollution out of area	*Throughout the ozone smog season (May through September), residents should make an extra effort to:* Carpool, use transit, bike, or walk when possible. Keep cars and boats tuned. Use environmentally safe paints and cleaning products.

Air Quality Hotline

Mayland Department of the Environment (410) 631-3247 (Baltimoe)

Metropolitan Washington Council Of Governments (202) 962-3299 (Wahington)

Ground-Level Ozone

Ground-level ozone presents a serious air quality problem in central Maryland and throughout the Washington metropolitan area. Air quality in these areas exceeds the federal health standard for ozone on numerous days each summer.
Ozone is a major element of urban smog. Ozone can lower resistance to diseases such as colds and pneumonia, damage lung tissue, intensify heart and lung disease, and cause coughing and throat irritation.
Even healthy adults who perform heavy physical exercise or manual labor outdoors experience the unhealthful effects of ozone.
Other sensitive persons include the young, elderly, and those with pre-existing lung problems.

What Is Ozone?

Ozone is a colorless gas that can be found in the air we breathe. Each molecule of ozone is composed of three atoms of oxygen, one more than the oxygen molecule which we need to breathe to sustain life. The additional oxygen atom makes ozone extremely reactive. Ozone exists naturally in the earth's upper atmosphere, the stratosphere, where it shields the earth from the sun's ultraviolet rays. However, ozone found close to the earth's surface, called ground level ozone, is considered an air pollutant.

Where Does Ground Level Ozone COme From?

Ozone is formed by a chemical reaction between volatile organic compounds (VOCs) and oxides of nitrogen in the presence of sunlight. The primary sources of VOCs and oxides of nitrogen are automobile and industrial emissions. Other sources of VOCs include dry cleaners and consumer products such as paints, insecticides, and cleaners. Ozone concentrations can reach unhealthful levels when the weather is hot and sunny with little or no wind. High ozone levels usually occur between 1:00 and 7:00 pm from May through September.

How Does Ozone Affect Human Health?

High concentrations of ozone may cause inflammation and irritation of the respiratory tract, particularly during heavy physical activity. The resulting symptoms may include coughing, throat irritation, and breathing difficulty. Inhaling ozone can affect lung function and worsen asthma attacks. Ozone may increase the susceptibility of the lungs to infections, allergens, and other air pollutants. Medical studies have shown that ozone damages lung tissue and that unhealthful effects may continue for days after exposure has ended.

How Dodes Ozone Affect Plant Life?

There is clear evidence that ozone harms vegetation and forests. A 1988 study conducted by the EPA found that ozone pollution was reducing American crop yields by $3 billion each year. The study showed that, in the hot summer of 1988, ozone reduced crop yields in experimental plots by as much as 30 percent. Ozone pollution also harms forests because it causes early leaf drop and lower growth rates.

Air Quality Index (Ozone Levels)	Corresponding Color Coded Forecast
0-50	Code Green
51-88	Code Yellow
89-99	Code Orange
100+	Code Red

Endzone

Partners to End Ground-Level Ozone

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