What is air pollution? [Back to Top]
Air Pollution is a general term for many different substances in the air. Pollution generally means a man-made substance that is harmful to human health, to wildlife and plant populations, or to other parts of the environment. Some pollutants are completely man-made and don't occur naturally in the environment. Some substances occur in nature, but are also produced in large amounts by human activities. These substances are considered pollutants because in the higher concentrations produced by humans, they are harmful to human health and/or the environment. An example of this type of pollutant is ground-level ozone, which occurs naturally in very small amounts but is harmful in the large concentrations produced by humans.

What air pollutants are regulated? [Back to Top]

What is a criteria air pollutant? [Back to Top]
Under the authority of the Federal Clean Air Act, passed in 1970 and amended in 1990, the U.S. Environmental Protection Agency (EPA) sets standards, or criteria, for six pollutants that are deemed harmful to human health and the environment. These "criteria pollutants" are nitrogen dioxide, sulfur dioxide, lead, carbon monoxide, ground-level ozone and particulate matter. The EPA's primary standards protect human health, and secondary standards for some pollutants protect public welfare and the environment.

Other hazardous or toxic airborne chemicals are also regulated by the Federal government and North Carolina.

How do we know how much pollution is in the air? [Back to Top]
The Clean Air Act requires states to monitor levels of all criteria pollutants, using special monitoring equipment. These monitor readings are reported to the EPA. The NC Division of Air Quality's Ambient Monitoring Section is responsible for monitoring the air in most of North Carolina. You can find peak air quality monitor readings for the past 24-36 hours, as well as statistical summaries and reports of past air quality, at the Ambient Monitoring Section's websiteAmbient Monitoring Section's website.

NCDAQ also forecasts daily air quality from May 1 - September 30 for several areas of North Carolina, and year-round for Charlotte. The air quality forecasts give you warning of high pollution levels and can help you plan your activities to protect your health and the environment.

How polluted is North Carolina's air? [Back to Top]
North Carolina is meeting the federal standards for four criteria pollutants: nitrogen dioxide, sulfur dioxide, lead, and carbon monoxide. However, several areas in North Carolina are violating the ground-level ozoneground-level ozone standard as well as the fine fine particulate matterparticulate matter annual standard.

Because air pollution levels are often influenced by weather conditions, some years are worse than others. In 2002, a hot, dry year, we experienced 29 Ozone Action Days of air quality code orange or red in the Triangle, 31 in the Triad, and 36 in the Charlotte area. That's about a month of unhealthful air conditions in each of North Carolina's three major population centers. The Division of Air Quality's Ozone Forecasting Center has compiled historical statistics of ozone levels in North Carolina's ozone forecast areas.

What is the color-coded Air Quality Index and how is it used?[ [Back to Top]
The Air Quality Index (AQI) is a tool used to report levels of ozone, particles and other pollutants in the air to the public. The AQI scale is divided into five color-coded categories, each corresponding to a different level of health concern running from green (good) to purple (very unhealthy). You can think of the AQI as a yardstick that runs from 0 to 500. The greater the AQI value, the greater the level of air pollution, and the greater the health danger. particulate matter annual standard.

The air quality color codes are:

The AQI color codes are used for air quality forecasts and for air quality reporting. The forecast, available year-round in the Triad and Charlotte, and May 1 - September 30 in Asheville, Fayetteville, Hickory, and the Triangle, predicts anticipated pollution levels using the AQI color code. For example, your local newspaper might report that the forecast is orange with an AQI of 110, indicating that air pollution levels are expected to be "unhealthy for sensitive groups".

Air quality reports give either current pollution levels detected by monitors, or air pollution levels that have already occurred, usually during the previous day. For reports of recent air quality levels in many areas of North Carolina, visit http://daq.state.nc.us/monitor/aqi/ or call 1-888-AIRWISE (1-888-247-9473). Reports of current and recent air quality levels in Mecklenburg County are found at http://maps.co.mecklenburg.nc.us/website/airquality/ or by calling (704) 333-SMOG (7664).

What is an Air Quality Action Day?[ [Back to Top]
An Air Quality Action Day is announced when pollution levels are forecasted to be Code Orange, Red or Purple, those levels above the Federal health standard. From May 1 - September 30, most Air Quality Action Days will be for ozone, although a few code orange particulate days may occur during this period. From October 1 - April 30, particle pollution is forecasted for the Triad and Charlotte areas, and Air Quality Action Days during this period will be for particles. On Air Quality Action Days, North Carolinians are asked to take ACTION to reduce air pollution and to protect their health.

What can I do to improve North Carolina's air quality?[ [Back to Top]
Ozone and particle pollution, the two biggest air quality concerns in North Carolina, come from many of the same sources, primarily motor vehicles and industry, including power plants. Our individual activities create air pollution, and all of us have the power to improve air quality through our actions. If everyone did a little, our air quality would improve a lot. Try some of the following:

• Leave your car. Take the bus, car pool, van pool, walk or ride your bike to your destination.
• Take your lunch instead of driving out to eat. Or walk to a nearby restaurant.
• Drive it right. When you do drive your car, use cruise control whenever practical and stay within the speed limit. Avoid sudden stops and starts. Plan your trips to combine short trips whenever possible, to avoid cold starts.
• Stay tuned. Keep your car, boat, and lawn equipment tuned up. Engines that are well-maintained are more fuel efficient and cause less pollution. Follow your car's maintenance schedule and get a tune-up once a year. After all, it makes good economical and environmental sense. Reduce wintertime particulate pollution by keeping your oil furnace well-maintained.
• Don't idle. Avoid idling in drive-through lanes; park and walk in instead. Idling your vehicle for more than one minute wastes gas and increases pollution, when compared to shutting off and re-starting your engine.
• Choose clean. Your vehicle may be your single biggest impact on air quality. Make air quality a priority by factoring emissions and fuel efficiency into your vehicle purchasing decisions. Find how vehicles compare at www.epa.gov/greenvehicles/ and www.fueleconomy.gov/.
• Don't go flat. Keep your tires properly inflated. You'll save gas and reduce tire wear too.
• Don't top off! When refueling your vehicle, stop at the click to avoid spilling gas and polluting the air and water.
• Conserve electricity. Set your air conditioning at the highest comfortable temperature (try 78 degrees). During winter, try a setting of 68 - 70 degrees to reduce electricity use by heat pumps and particulate pollution from oil furnaces. Use ceiling fans to increase both cooling and heating efficiency. Turn off appliances when not in use. Look for the Energy Star label when purchasing major appliances.
• Cut it out. The small engines in lawn care equipment are major polluters. Use hand-powered or electric lawn care equipment whenever possible, and consider landscaping to reduce the amount of lawn. On Air Quality Action Days, wait until after 6:00 p.m. to use gas-powered lawn equipment.
• Do it at dusk. Postpone refueling your car until after 6 p.m. on Air Quality Action Days. This reduces the emissions during the peak daylight hours when ozone formation is most likely.
• Try something different. Use water-based paints and cleaners instead of solvent-based products.

What is the Air Quality Coalition?[ [Back to Top]
The Air Quality Coalition is a partnership of businesses, governments, and organizations motivated to improve North Carolina's air quality, and the quality of life of their employees and members. Coalition organizations inform their employees about air quality by distributing the air quality forecast and providing education about air quality issues and actions. Some Coalition organizations help their employees improve air quality by providing incentive programs for carpooling and transit. Over 500 partners participate in local Air Quality Coalitions in the Asheville, Charlotte, Hickory, Triad, and Triangle areas, educating thousands of people about air quality. If you'd like your organization to become a member of the Air Quality Coalition, send an email to Air.Awareness@ncmail.net or contact Milli.Hayman@ncmail.net .

What is North Carolina doing to inform citizens about air pollution and its effects?[ [Back to Top]
The NC Air Awareness Program was created to inform North Carolina's citizens about air pollution and its effects. The program is an active partnership between the North Carolina Division of Air Quality, county environmental agencies, health departments, local governments and transit providers, businesses, citizen organizations, educators, and the media. Through www.ncair.org, 1-888-RU4NCAIR, brochures, school visits, public events, local media coverage, and through the Air Awareness Coalition, we work to educate the public about air quality issues. The program seeks to inform citizens as to how their daily actions affect air quality, and how they can protect their health and the health of their environment by making simple lifestyle adjustments that show they care for the air. It's just a matter of taking the time to Think, Act and Breathe... a little easier.

Where can I get real-time air quality information?[ [Back to Top]
Information on current Raleigh-area air quality is available from the N.C. Division of Air Quality's website. Current information for Mecklenburg County monitors is available from the Mecklenburg County Air Quality agency nd by calling (704) 333-SMOG (7664). The N.C. Division of Air Quality is currently working to make more real-time air quality information available on our website.

You can also find maps of current air quality conditions for areas around the country, as well as air quality forecasts, on EPA's AIRNow web site.

Where can I get historical air quality data?[ [Back to Top]
You can find peak air quality monitor readings for the past 24-36 hours, as well as statistical summaries and reports of past air quality, at the N.C. Division of Air Quality Ambient Monitoring Section's website. For data from locations nationwide, visit the EPA Office of Air Quality Planning and Standards Air Pollution Monitoring web site.

Ozone forecast verifications, past ozone concentration information, and ozone monitor statistics are available from the NC Ozone Forecast Center.

What is particle pollution? [Back to Top]
Particle pollution (also known as "particulate matter") is a mixture of tiny solids and liquid droplets suspended in air. Airborne particles are the main ingredient in haze, smoke and airborne dust. Particles are made up of a variety of components; including acids (such as nitrates and sulfates), organic chemicals, metals, elements from soil or dust, and allergens (for example, fragments of pollen or mold spores).

Particles come in a wide range of sizes. Those less than 10 micrometers in diameter are so small that they can be inhaled into the lungs, potentially causing serious health problems. Ten micrometers is much smaller than the width of a single human hair (which is 70 micrometers in diameter). Particles less than 2.5 micrometers in diameter are called "fine" particles, and are of special concern because they can penetrate deeply into the lungs. Particles between 2.5 and 10 micrometers in diameter are referred to as "coarse" particles.

Where does particle pollution come from? [Back to Top]
Some particles are directly emitted, like dust, or the "soot" particles in diesel exhaust. Other tiny particles are indirectly formed when chemicals like sulfates, nitrates, and carbon condense and combine in the air. Sources of fine particles include all types of combustion from a number of sources, including cars and trucks, power plants and other industry, and residential fireplaces and wood stoves. Because cars and trucks are a major source, particle levels are generally higher near busy roadways. Diesel-powered vehicles and engines contribute more than half of motor vehicle fine particulate emissions. Indoor sources of particle pollution include smoke from tobacco, wood stoves, candles, fireplaces, and emissions from natural gas stoves.

Sources of coarse particles include crushing or grinding operations, dust stirred up by vehicles traveling on unpaved roads, and windblown dust.

Scientists are still working to understand the sources of particle pollution and how various aspects of this pollutant affect human health.

How do particles affect human health? [Back to Top]
When inhaled, particles can be deposited in the airways or deep in the lungs. Once deposited, several things may happen. Particles may be cleared by the body's natural defense mechanisms, they may accumulate on the surface where they deposit, or they may be absorbed into the underlying tissues. The soluble components of fine particles, along with very small ("ultrafine") particles, may enter the bloodstream. Some particles may react chemically in the body; others remain in their original form.

The most serious effects of particles are associated with heart or lung disease. Numerous studies have linked particle pollution to increased admissions to hospitals and emergency room visits, and even to death from heart or lung diseases. Short-term exposure has been linked to aggravation of lung diseases, including asthma attacks and acute bronchitis. In people with heart disease, particles have been linked to heart attacks and cardiac arrhythmias (irregular heart rhythms). Recent evidence suggests that some of these effects may result from very short-term exposures, possibly as short as an hour. Epidemiologists have found that mortality rates and hospitalization rates increase when particulate pollution rises even a moderate amount. Epidemiologists link thousands of yearly fatal heart attacks in the U.S. to particulates.

A 16-year study published in March 2002 in the Journal of the American Medial Association provides evidence that long-term exposure to fine particles significantly increases the risk of illness and death from lung cancer and heart disease. The level of lung cancer risk associated with exposure to fine particles emitted by coal-fired power plants, factories and diesel trucks is comparable to the risk posed by long-term exposure to second-hand smoke from cigarettes.(1) American Cancer Society and Harvard University epidemiological studies recently showed that people living in more polluted cities had an increased risk of premature death compared to those in cleaner cities.

Particle exposure might also increase susceptibility to bacterial or viral respiratory infections, leading to increased risk of pneumonia in vulnerable individuals. In the presence of pre-existing heart disease, acute bronchitis or pneumonia induced by air pollutants might precipitate congestive heart failure.

In healthy children and adults, exposure to elevated particle levels for short periods of time may cause minor irritation. Most healthy people will recover quickly from these effects and are unlikely to experience long-term health problems. However, long-term exposure to particles has been associated with reduction in lung function and the development of chronic bronchitis.

(1) Pope et al. 2002. Lung Cancer, Cardiopulmonary Mortality, and Long-term Exposure to Fine Particulate Air Pollution. J. Am. Med. Assoc. 287(9):1132-1141.

Who is affected by particle pollution? [Back to Top]
Everyone's health can be at risk when particle pollution levels are high, but some groups of people are also at risk at lower levels. Those groups include people with heart or lung disease, older adults (men over 45 and women over 55), and children.

People with heart or lung diseases such as congestive heart disease, coronary artery disease, asthma, or chronic obstructive pulmonary disease (COPD) are at risk because particles can aggravate these conditions. In addition, the obstructed air flow in people with COPD may cause more particles to deposit in their lungs. People with diabetes may be at increased risk of serous effects, possibly because of underlying cardiovascular disease.

Older adults are at increased risk, possibly because they are more likely to have either diagnosed or undiagnosed heart or lung disease or diabetes.

Children may be more vulnerable to particles because their lungs are still developing, and they breathe more air in relation to body weight than do adults. In addition, they spend more time at higher activity levels, and are more likely to have asthma or acute respiratory diseases.

Factors that increase the risk of heart attack may also increase your risk from particles. These include: age, family history of heart disease, smoking, high blood pressure, high blood cholesterol, obesity, physical inactivity and diabetes.

The risks of health effects are increased by physical activity during periods of elevated particle pollution. When you are physically active, you breathe faster and more deeply, taking more air and more particles into your lungs.

Scientists do not yet know if pregnant women are at increased risk from particle pollution. Studies suggest that breathing high particle levels over long periods of time may be associated with low-birth-weight infants, pre-term deliveries, and fetal and infant deaths.

What are the symptoms of particle pollution exposure? [Back to Top]
Even if you are healthy you may experience temporary symptoms from exposure to elevated levels of particles. Symptoms may include; irritation of the eyes, nose and throat, coughing; phlegm; chest tightness; and shortness of breath.

If you have lung disease, you may not be able to breathe as deeply or as vigorously as normal, and you may experience respiratory symptoms such as coughing, chest discomfort, wheezing, shortness of breath, and unusual fatigue. If you experience these symptoms, you should reduce exposure and activity level, and follow the advice of your doctor. If you have asthma, you should already have an asthma action plan, but you may need to follow it more carefully when particle levels are high.

If you have heart disease, you can have serious effects, such as heart attacks, with no warning symptoms. The absence of symptoms does not mean that you are safe. If you do experience symptoms - such as chest pain or tightness, palpitations, shortness of breath, or unusual fatigue - contact your doctor as these symptoms may indicate a serious problem.

What level of exposure to particulates is considered unhealthy? [Back to Top]
People have experienced health problems from exposure to particles over long periods (years) and from periods as short as 1 to 24 hours. Epidemiological studies have reported a linear relationship between exposure and effects. The higher the concentration of particles, the greater the effect on the health of populations. Scientists have not been able to identify a threshold below which health effects do not occur. According to the World Health Organization, long-term epidemiology studies show that the risk of premature deaths starts to increase at fine particle annual average concentrations of 10 micrograms per cubic meter (µg/m3).

The EPA has set an annual and a 24-hour standard for fine particulate pollution to protect human health. The annual standard is 15 µg/m3. This represents particle levels averaged over an entire year, and is designed to protect the public from long-term exposure. The 24-hour standard is 65 µg/m3, and protects against short-term exposure to higher particle levels.

How can I reduce my risk from particle exposure? [Back to Top]
Your chances of being affected by particles increase the longer you are active outdoors, and the more strenuous the activity you engage in. If you're involved in an activity that requires prolonged or heavy exertion, you can reduce the time you spend on the activity or substitute another activity that requires less exertion - for example, go for a walk instead of a jog. You can also plan outdoor activities when and where particle levels are lower. In general, levels of particles and other pollutants are higher near busy roadways, so avoid heavy exertion - like jogging or biking - in these areas.

Daily air quality forecast for the Greater Charlotte Triad areas of North Carolina give notice of anticipated high particle levels. People in at-risk groups should take special care to reduce exposure at Code Orange air quality levels or higher; everyone should exercise caution at code red levels.

Particle levels can sometimes be elevated indoors, especially if particles in the outdoor air are elevated and there are indoor sources, such as tobacco smoke. Certain filters and room clearer are available that can help reduce particle levels indoors. Ozone-producing air cleaners (sometimes called "activated oxygen" air cleaners) should not be used in occupied spaces as they may cause unhealthy levels of ozone to accumulate. You can also reduce indoor sources of particles by eliminating tobacco smoke and reducing your use of candles, wood-burning stoves and fireplaces.

What time of year is particle pollution a problem? [Back to Top]
Unlike ozone, particle pollution occurs year-round. Particle pollution levels can be high inside or outside. When particle pollution levels are high it is important to limit physical activity, even if that activity occurs indoors.

Unusual events sometimes increase particle pollution to high levels. Occasionally a plume of smoke from a distant forest fire will elevate local particle levels. After the December 2002 ice storm, many Triangle area residents without electricity burned wood for warmth. At the same time, an atmospheric inversion concentrated the wood smoke, resulting in Code Red particle pollution levels in the Triangle.

What time of day are particle pollutions levels high? [Back to Top]
Unlike ground level ozone pollution, particle pollution levels can be high in the morning or in the afternoon. It is important to know the Air Quality Index Color Code forecast for the day and limit or avoid activity - inside or out, morning or evening - on days when particulate pollution levels are high.

How do I know when particle levels are high? [Back to Top]

What areas of N.C. have a particle pollution forecast? [Back to Top]

Where can I find the particle pollution forecast? [Back to Top]
Daily air quality forecasts are issued for the Triad and the Charlotte areas. These forecasts will warn you of expected high particle levels. During the warm-weather season of May 1 - September 30, the forecasts will also warn of high ozone levels. You can find the forecast in the weather section of your local newspaper or during the weather segment of your local television news. You may also hear it on some radio stations. Some national media, such as USA Today and The Weather Channel, also provide air quality information.

You can find the particle forecast at http://daq.state.nc.us/airaware/forecast/ for the Charlotte area, and at www.co.forsyth.nc.us/envAffairs/DlyAirQualRpt.htm for the Triad. You can also call 1-888-RU4NCAIR (1-888-784-6224) to hear forecasts for both areas. Forecasts are issued at approximately 3:00 each day, and predict air quality for the following day.

In Mecklenburg County, you can find real-time air quality information for selected monitors at http://maps.co.mecklenburg.nc.us/website/airquality/. This information will let you know when local particle levels are already high.

How can I receive the particle pollution forecast directly? [Back to Top]
Any individual or organization can receive the forecast by email or fax. For the Charlotte area particle forecast, simply send an email to Air.Awareness@ncmail.net to request the forecast. Specify whether you want to receive daily forecasts, or only Air Quality Action Day (Code Orange or higher) forecasts. Be sure to include the email address or fax number to receive the forecast. You can also call 1-888-RU4NCAIR (1-888-784-6224) to request the forecast.

If you are with a business, government agency, or organization, consider signing up for your local Air Quality Coalition. Coalition members distribute the Air Quality Action Day forecasts to their employees or organization members, and provide air quality education. In this way, Coalition members help to improve both air quality and public health. Contact Air.Awareness@ncmail.net or call 1-888-RU4NCAIR for more information.

What can I do to reduce particle pollution? [Back to Top]
Because particle sources include vehicles and power plants, you can help reduce particle pollution by driving less, keeping your car well-maintained, and conserving energy. Some specific ways to help are found near the beginning of this document.

One important way to help reduce particle levels is by avoiding backyard burning, sometimes called open burning. Burning non-vegetative trash is illegal everywhere in North Carolina, and burning yard waste is illegal in many municipal areas with yard waste pickup. Although burning yard waste may seem harmless, the particle-rich smoke from your backyard fire could harm others in your community, especially if they have heart or lung problems. Compost or mulch your yard waste instead.

Your business or agency can help reduce pollution and improve employee satisfaction by becoming a CCLI-recognized Best Work Place for Commuters. For more information on this innovative program, visit www.commuterchoice.gov or contact marti.mattox@ncmail.net.

What is ozone? [Back to Top]
Ozone is an ionic form of oxygen with 3 oxygen atoms (O3). By contrast, the form of oxygen we breathe has two atoms (O2). The extra oxygen atom makes ozone very unstable and thus highly reactive. Ozone occurs naturally in the upper atmosphere, but is created by human activities at ground level. Ozone has the same chemical structure whether it occurs high above the earth or at ground level, and can be "good" or "bad," depending on its location in the atmosphere.

Is ozone good or bad? [Back to Top]
The naturally-occurring ozone layer in the upper atmosphere, or stratosphere, protects the earth from the sun's ultraviolet radiation. Obviously, stratospheric ozone is "good" ozone, and the depletion of stratospheric ozone continues to be of major concern.

However, ozone does not occur naturally in the lower atmosphere, except in very small amounts. Most of the ozone at ground level is produced by human activities. Ground-level or "bad" ozone is an air pollutant that damages human health, vegetation, and even man-made materials such as fabric and rubber.

Is ozone the same thing as smog? [Back to Top]
The term "smog" is often used to refer to ground-level ozone pollution. When you see or hear the word smog used in a news report about air pollution, you can usually assume that the report is referring to ozone pollution. Ozone combines with particle pollution to form the dirty-looking urban haze that many people think of as smog. So although ozone and smog are not technically the same thing, ozone is a necessary ingredient of smog. However, it's important to remember that ozone levels can be high, even on a clear day with no visible "smog".

What North Carolina areas have an ozone problem? [Back to Top]
Typically, high ozone pollution levels occur in urban areas where there are lots of cars, industry and other sources of combustion. However, ozone can travel with the wind to rural areas and become a problem in those areas as well. In North Carolina, our greatest areas of concern are the Charlotte area, the Triad (Greensboro, Winston-Salem, and High Point), and the Triangle (Raleigh, Durham, and Chapel Hill). However, several other areas of North Carolina have a problem with high ozone levels and are in exceedence of EPA's 8-hour ozone standard.

How is ozone formed? [Back to Top]
Ground-level ozone forms when nitrogen oxides (NOx) react with volatile organic compounds (VOCs) in the presence of heat and sunlight.

VOCs, or hydrocarbons, come from man-made sources such as cars, service stations, dry cleaners and factories as well as natural sources such as trees and other vegetation. Because VOCs are volatile, or highly reactive, they evaporate easily and typically have a strong smell. Fumes from gasoline, paint thinners and solvents, and even printer ink are all VOCs, as are the fragrances in perfumes, soaps, and other consumer products. Naturally-occurring VOCs from trees and vegetation are sometimes called biogenic emissions, while man-made emissions are referred to as anthropogenic.

NOx is a byproduct of combustion, and comes from coal-fired power plants, industrial boilers, motor vehicles, lawn-care equipment and other sources that burn fuel. In some North Carolina urban areas, up to 70% of ozone-forming NOx comes from motor vehicles.

Efforts to control ozone focus on NOx because most of it comes from man-made sources that can be controlled. Reducing VOCs is less effective because pines, oaks and other trees that are so abundant in the South emit large amounts of hydrocarbons.

Most of the ozone in urban areas comes from local sources. However, winds can carry ozone from cities to surrounding rural areas and even to other states. Much of the ozone pollution at high elevations in the mountains of Western North Carolina is transported by winds from other states. In mountain valleys, however, ozone-forming pollution can come from both local and out-of-state sources.

Why is ground-level ozone a problem? [Back to Top]
Ozone is a strong respiratory irritant, and can cause serious health problems, especially for sensitive groups: children, people with asthma and other respiratory ailments, and anyone who works or exercises vigorously outdoors. Symptoms of ozone exposure can include coughing, throat irritation, chest pain, rapid and shallow breathing, and asthma attacks. Emergency room visits for asthma have increased as much as 36 percent on high ozone days, according to some studies. High childhood exposure to ozone pollution may reduce lifetime lung function.

High ozone levels also damage vegetation, reducing growth rates and crop yields. More details on the health and environmental effects of ozone can be found later in this section.

What is the ground-level ozone standard in NC? [Back to Top]
The Federal standard for ground-level ozone is 0.085 parts per million (ppm), averaged over an 8-hour period. This is often referred to as the "8-hour standard and replaces an older "1-hour standard" of 0.125 ppm. Levels of 0.085 ppm and above exceed the Federal ground-level ozone standard. Codes Orange, Red, and Purple AQI are above the standard.

What does "ppm" mean? [Back to Top]
Parts per million, or ppm, is a ratio that describes how many parts of something you have per one million equally-sized parts of something else. So, with the 8-hour standard, the maximum healthy concentration of ground-level ozone is less than 1/10th of one part of ozone per one million parts of air!

These examples might help:

If a pie is divided equally into 10 pieces, each piece would be a part-per-ten; i.e., one-tenth of the total pie. If the pie is cut into 100 pieces, each piece would be one part-per-hundred, or one percent, of the pie. If this pie is cut into a million pieces, each piece would be very small and would represent a millionth, or part per million, of the original pie. If each of the million minute pieces is cut into a thousand little pieces, each of these new pieces would be a part per billion of the original pie. To give you an idea of how little this would be, a pinch of salt in 10 tons of potato chips is one part per billion (ppb). Thus, a part per billion of the pie would be invisible to you.

Four drops of ink in a 55-gallon barrel of water would produce an "ink concentration" of 1 ppm.

One drop of ink in one of the largest tanker trucks used to haul gasoline would represent 1 ppb.

What are the health effects of ground-level ozone? [Back to Top]
Ozone is a strong respiratory irritant. Short-term, infrequent exposure to ozone can result in throat and eye irritation, difficulty drawing a deep breath, and coughing. Long-term and repeated exposure to ozone concentrations above the Federal standard can result in reduction of lung function as the cells lining the lungs are damaged. Repeated cycles of damage and healing may result in scarring of lung tissue and permanently reduced lung function. Health studies have indicated that high ambient ozone concentrations may impair lung function growth in children, resulting in reduced lung function in adulthood. As lung function declines in older adults, individuals whose lung function is already below normal may be especially vulnerable to respiratory problems.

Asthmatics and other individuals with respiratory disease are especially at risk from elevated ozone concentrations. Ozone can worsen, and may trigger, asthma attacks. Ozone may also contribute to the development of asthma. A recent study published in the British medical journal The Lancet found a strong association between elevated ambient ozone levels and the development of asthma in physically active children.(2)

All children are at risk from ozone exposure because they often spend a large part of the summer playing outdoors, their lungs are still developing, they breathe more air per pound of body weight, and they are less likely to notice symptoms.

Children and adults who frequently exercise outdoors are particularly vulnerable to ozone's negative health effects, because they may be repeatedly exposed to elevated ozone concentrations while breathing at an increased respiratory rate.

(2) McConnell et al. 2002. Asthma in exercising children exposed to ozone: a cohort study. Lancet 359: 386-391.

What are the harmful environmental effects of ozone pollution?  [Back to Top]
Water Pollution: The nitrogen oxides that contribute to ozone pollution also fall back to the earth as nitrogen compounds, contributing to nutrient pollution of streams, rivers, and estuaries. As much as half of the nitrogen pollution in North Carolina's coastal waters may come from air pollution. Nutrient pollution contributes to algal blooms, reduced oxygen content of water, and fish kills.

Plant and Crop Damage: Ozone pollution can damage plant tissues, reducing growth rates and agricultural yields. It interferes with the ability of plants to produce and store food, making them more susceptible to disease, insects, other pollutants, and harsh weather. In 1995, ozone pollution caused $2.7 billion in crop loss nationwide, according to the U.S. EPA. Ground-level ozone damages the foliage of trees and other plants, impacting the landscape of cities, national parks and forests, and recreation areas.

How do weather conditions affect ground-level ozone? [Back to Top]
Sunlight, temperature, atmospheric stability, and wind conditions all affect the formation and accumulation of ground-level ozone. Ultraviolet radiation from sunlight drives the reaction between NOx and VOCs to form ozone, so ozone pollution increases on clear or partly cloudy days. Like many chemical reactions, ozone formation increases as temperatures rise. In addition, temperature affects ozone-forming emissions (e.g., evaporative emissions of VOCs and biogenic emissions increase with high temperatures). Atmospheric stability (temperature change by height) controls the amount of vertical air mixing that takes place. Strong stability tends to reduce mixing (dilution) of ground-level ozone and ozone-forming emissions. During atmospheric inversions, air higher in the atmosphere is warmer than air below, preventing lower air from rising and mixing. Inversions thus concentrate air closer to the surface, sometimes resulting in higher ozone levels. Wind conditions affect the dispersal and dilution of air and pollutants. Calm or light winds allow more pollution to concentrate in an area. Upper-level winds are also important because they can transport ozone and ozone great distances during the overnight period.

Ozone concentrations tend to be highest on sunny, hot days with little to no wind.

When is the ground-level ozone season in NC? [Back to Top]
Because hot, sunny conditions are needed for elevated ozone levels, ozone is only a problem during the warm-weather months. The ozone forecast season, when N.C. Division of Air Quality forecasts daily ozone levels, is May 1 - September 30. Ozone levels are monitored from April 1 - October 30, although ozone levels rarely exceed the standard in April and October.

What time of day are ground-level ozone levels the highest? [Back to Top]
Ozone begins forming in the morning and formation increases as temperatures increase during the day. Ozone accumulates through the day, especially when winds are calm. In most areas of North Carolina, ozone levels peak during mid-afternoon through early evening, when temperatures are hottest. Ozone levels decrease as the sun sets, drop at night and are lowest around dawn. However, at high elevations (above 4,000 feet) in the mountains, ozone levels can remain high throughout the day and actually reach their highest values overnight.

When is it best to do exercise outdoors during ozone season? [Back to Top]
On Ozone Action Days, it's safest to exercise in the morning, when ozone levels are lowest. Morning is a good time for biking, walking, jogging or other types of strenuous outdoor activities. At high elevations in the mountains, ozone levels can remain high throughout the day and night during bad air events - so people should limit outdoor activities if they notice signs of problems such as coughing and breathing difficulty.

By paying attention to the daily ozone forecast, you can plan your exercise schedule. On Ozone Action Days of Code Orange and above, try to schedule exercise for the morning, and avoid strenuous exercise in the afternoon. Although ozone levels are generally not as low at dusk as in the morning, ozone levels during dusk and evening are usually safe for exercise. On Code Green days, you are safe exercising any time of the day, and most people are safe exercising on Code Yellow days as well. On "high" Code Yellow days when the AQI is predicted to be close to 100, very sensitive people may need to limit or avoid afternoon exertion.

If you are considering exercising at high elevations in the mountains, the Asheville Ridge Top forecast will alert you to days when ozone levels may be elevated during daytime and nighttime hours.

What is the ozone forecast? [Back to Top]
The NC Division of Air Quality issues a ground-level ozone forecast every day from May 1st through September 30th that consists of a color-coded forecast and a corresponding Air Quality Index (AQI) number. The color code and AQI value predict the maximum 8-hour ozone concentration for the following day. This information is distributed via email, fax, media outlets, and the North Carolina Ozone Forecast Center web site. The ground-level ozone forecast allows citizens not only to plan outdoor activity to protect their health, but also to take action to reduce ozone-forming emissions.

When are the ground-level ozone forecasts issued? [Back to Top]
Ground-level ozone forecasts are issued everyday from May 1st through September 30th at 3:00 pm EDT. A "forecast discussion", also issued at 3:00 pm EDT, provides a detailed description of the current ozone and meteorological conditions which the forecaster has considered in making the forecast. A "morning edition" is available around 10:00 am EDT each day. The morning edition provides additional information specifying whether the current forecast appears to be on track.

Is there a ground-level ozone forecast for my area? [Back to Top]
Between May 1 and September 30, look for the ozone forecast in the weather section of your local newspaper and during the weather segment of your local television news. You may also hear it on some radio stations. Some national media, such as USA Today and The Weather Channel, also provide air quality information.

The NC Division of Air Quality issues ground-level ozone forecasts for the Asheville, Hickory, Charlotte, Triangle and Fayetteville metropolitan regions of North Carolina. Additionally, the Forsyth County Environmental Affairs Department issues an air quality forecast for the Triad area. There is a ground-level ozone forecast for your area if you live or work in one of the counties associated the following forecast regions:

• Asheville: Buncombe, Haywood, Henderson, Jackson, Madison, Transylvania, Swain, and Yancey Counties.
• Hickory: Alexander, Catawba, Southeastern Burke and Southeastern Caldwell Counties.
• Charlotte: Cabarrus, Gaston, Lincoln, Mecklenburg, Rowan, Union, and Southern Iredell Counties, NC; and York County SC.
• The Triad: Alamance, Caswell, Davidson, Davie, Forsyth, Guilford, Randolph, Rockingham, and Stokes Counties.
• The Triangle: Chatham, Durham, Franklin, Granville, Johnston, Orange, Person, Vance, and Wake Counties.
• Fayetteville: Harnett and Cumberland Counties.

Where can I find the ozone forecast? [Back to Top]
Between May 1 and September 30, look for the ozone forecast in the weather section of your local newspaper and during the weather segment of your local television news. You may also hear it on some radio stations. Some national media, such as USA Today and The Weather Channel, also provide air quality information.

You can find the forecast at http://daq.state.nc.us/airaware/ozone/ for all areas except the Triad, and at http://www.co.forsyth.nc.us/envAffairs/DlyAirQualRpt.htm for the Triad. You can also call 1-888-RU4NCAIR (1-888-784-6224) to hear forecasts for all areas. Forecasts are issued at approximately 3:00 each day, and predict air quality for the following day.

How can I receive the ground-level ozone forecast directly? [Back to Top]
Any individual or organization can receive the ozone forecast by email or fax. Simply send an email to Air.Awareness@ncmail.net to request the forecast. Specify which area's forecast your want, and whether you want to receive daily forecasts, or only Air Quality Action Day (Code Orange or higher) forecasts. Be sure to include the email address or fax number to receive the forecast. You can also call 1-888-RU4NCAIR (1-888-784-6224) to request the forecast.

To request the Triad forecast, visit http://www.co.forsyth.nc.us/envaffairs/airlist.htm.

How can I take action to reduce ozone pollution? [Back to Top]
Because the biggest source of ozone pollution in most areas is cars and trucks, anything you can do to drive less will help. Keeping your car well-maintained helps as well. Conserving electricity will reduce ozone pollution resulting from power plant emissions. A list of specific things you can do is near the top of this document. Remember, you have the power to clear the air, and if we all do a little, together we can reduce pollution a lot!

Your business, citizen organization, or agency can help reduce ozone pollution by joining the Air Quality Coalition. Coalition partners distribute the Air Quality Action Day forecasts to their employees or organization members, and provide air quality education. The combined efforts of over 500 Coalition partners statewide reach many thousands of people, improving both air quality and public health. Contact Air.Awareness@ncmail.net or call 1-888-RU4NCAIR for more information.

Your business or agency can also help reduce pollution and improve employee satisfaction by becoming a CCLI-recognized Best Work Place for Commuters. For more information on this innovative program, visit www.commuterchoice.gov or contact marti.mattox@ncmail.net.

Where can I find more air quality information? [Back to Top]

• Statewide: NC Air Awareness Program, Division of Air Quality: Toll free 1-888-RU4NCAIR (1-888-784-6224); www.ncair.org
• Hickory Area:http://www.wpcog.org/programs.asp?CID=0&PS=4
• Charlotte Area: Mecklenburg County Air Quality agency, (704) 336-5500, http://www.charmeck.org/Departments/LUESA/Air+Quality/Home.htm
• Triad Area: Forsyth County Environmental Affairs Department, (336) 727-8064, http://www.co.forsyth.nc.us/envaffairs/triadair/
• Asheville Area: Western North Carolina Air Pollution Control Agency, (828) 255-5655, http://www.eenorthcarolina.org/edresources/denrprograms/ashevilleair.htm
• Fayetteville Area:http://www.sustainablesandhills.org/pages/air_team_programs.html
• Triangle Area:http://www.triangleairaware.org/
• Health and Ozone: NC Division of Public Health, Occupational and Environmental Epidemiology, (919) 707-5900, www.dhhs.state.nc.us/ozone.htm
• National: US Environmental Protection Agency,

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