What is air pollution?
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 is the Air Quality Index?
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. You can find the local AQI forecast at North Carolina's Division of Air Quality web site.

AQI Colors
AQI Quality
AQI Numbers
0 to 50
51 to 100
Unhealthy for Sensitive Groups
101 to 150
151 to 200
Very Unhealthy
201 to 300

10 simple steps for improving air quality...
  • Trip chain more often, It's easy! Chances you are already doing it -- combining your errands into one trip. It helps you get things done and it helps reduce traffic congestion and air pollution. When you first start your car after it has been sitting for more than an hour, it pollutes up to five times more than when the engine is warm.
  • Take mass transit, share a ride or carpool. Even if you do it just once or twice a week, you will reduce traffic congestion and pollution, and save money. The average driver spends about 44 cents per mile including ownership and maintenance.
  • Have fun! Ride your bike. It is a great way to travel and it can help you and the air get into condition. Vehicles on the road create more than 25% of all pollution nationwide.
  • Take things in stride. Walk or in-line skate instead of driving. They are easy ways to get exercise and they are also easy on the air.
  • Care for your car. Regular maintenance and tune-ups, changing the oil and checking tire inflation can improve gas mileage, extend your car's life and increase resale value. It can also reduce traffic congestion due to preventable breakdowns and it could reduce your car's emissions by more than half.
  • Get fuel when it is cool. Refueling during cooler periods of the day or in the evening can prevent gas fumes from heating up and creating ozone. And that can help reduce ozone alert days.
  • Do not top off the tank. It releases gas fumes into the air and cancels the benefits of the pump's anti-pollution devices. So stopping short of a full tank is safer and reduces pollution.
  • Telecommute. Work at home sometimes. You will save time and money, and reduce emissions and traffic congestion.
  • Know before you go. Visit www.fampo.org/airquality or check the local paper or weather channel to verify the ozone forecast for the day.
  • Spread the word. If everyone took just a few of these simple, easy steps. It could make a big difference because it all adds up to cleaner air!

What is ozone?
Ozone is a gas made up of three 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?
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.

What are the health effects of ground-level ozone?
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.

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.

When is the ground-level ozone season in NC?
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. You can find the ozone forecast at North Carolina's Division of Air Quality web site. See how your actions affect ozone levels, find out how weather controls ozone, and learn how ozone affects your health at Smog City.

What time of day are ground-level ozone levels the highest?
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.

How can I take action to reduce ozone pollution?
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. Remember, you have the power to clear the air, and if we all do a little, together we can reduce pollution a lot!

What is particulate matter?
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 particulate matter come from?
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.

How do particles affect human health?
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.

What time of year is particle pollution a problem?
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.

Where can I find the particle pollution forecast?
Daily air quality forecasts are issued and 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 can find the particulate matter forecast at North Carolina's Division of Air Quality web site.

What can I do to reduce particle pollution?
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.