Pollution is a major problem across the United States. More than half of all Americans live in areas with unhealthy levels of outdoor smog or particle air pollution, according to a study by the American Lung Association. In addition, indoor air pollution such as secondhand smoke and combustion byproducts can present health risks.

Pollution can be especially dangerous for those who have allergies, asthma and other respiratory disorders. The irritants in pollution can easily trigger symptoms of an allergic cascade or asthma attack.

Individuals have little control over the amount of pollution in the atmosphere. However, those with illnesses sensitive to pollution levels can take several smaller steps to control their exposure to both indoor and outdoor irritants.

Pollution can trigger symptoms of many respiratory disorders, including asthma and allergies. The sources of pollutants are part of the fabric of everyday life and can be found both indoors and outdoors. Major environmental pollutants are released from:

• Chemical plants
• Steel mills
• Oil refineries
• Hazardous waste incinerators
• Automobiles, buses, airplanes and trains
• Dry cleaners
• Small metal plating operations
• Gas stations
• Crop fires and forest fires

Smoke stacks, equipment leaks or failures, explosions and accidents all release pollutants into the atmosphere. The concentration of a pollutant tends to be highest near the source of the pollution, and lower further away as the pollutant is dispersed and spread out through the air. Weather conditions – particularly wind speed and direction – also have a major impact on pollution concentration levels.

Many other pollutants are found not in the environment at large, but indoors in the home or workplace. Some of these pollutants seep in from outside, but others are generated inside the home. These include:

• Tobacco smoke. Secondhand smoke consists of smoke expelled out into the air by a smoker, as well as sidestream smoke produced by the burning end of a cigarette, cigar or pipe.
  
  
• Heating and air conditioning equipment (including wood stoves).
  
  
• Household cleaning products and personal care products. Ingredients that are potentially harmful include potassium hydroxide, perchloroethylene, methylene chloride, mercury, paradichlorobenzene and lead arsenate.
  
  
• Chemicals (e.g., formaldehyde, asbestos) released from construction and remodeling products, such as carpets, paneling and insulation.
  
  
• Radon, a gas from soil around the house that contains uranium. It enters the home through openings or cracks in the foundation floors, walls, drains or joints.

According to an American Lung Association (ALA) annual study, more than half of all Americans are living in counties that have unsafe levels of ozone or particle pollution. These pollutants place them at risk for decreased lung function, respiratory infection, lung inflammation and aggravation of respiratory illness.

Although pollutants have adverse effects on all people, certain people are at higher risk of problems from pollution exposure. They include:

• People with chronic lung disease such as asthma or chronic obstructive pulmonary disease (COPD)
• Children
• Seniors
• People with heart disease
• People with diabetes

Recent studies also indicate that air pollution may hamper lung development in children, possibly by keeping the lungs chronically inflamed and retarding the growth of the lungs’ air sacs (alveoli). Because the lungs stop growing by age 18 and lung capacity gradually declines thereafter, stunted growth can have lifelong consequences.

Both indoor and outdoor pollutants contain chemicals known to be harmful to human health when inhaled. Some of these chemicals include:

• Perchloroethylene, used in dry cleaning
  
  
• Methylene chloride, used in degreasers and consumer products such as paint strippers
  
  
• Benzene, used in gasoline and released when drivers fill their tanks or drive their cars
  
  
• Chromium, used in metal plating operations

The U.S. Environmental Protection Agency (EPA) has identified five pollutants that it considers to be particularly dangerous to human health. They include:

• “Bad” ozone. A mixture of oxygen, nitrogen, oxide gases and volatile organic compounds. It forms when sunlight and heat mixes with vapors and gases from fuel combustion, such as from car exhaust, power plants and other sources. This mixture combines with oxygen to create “bad” ozone. This is different from ozone in the upper atmosphere, which protects the Earth from ultraviolet light. This “good” ozone forms when ultraviolet light from the sun splits an oxygen molecule and forms two single oxygen atoms. These each bind to an oxygen molecule to form ozone.
  
  Ground-level ozone is potentially harmful. Ozone sears the cell walls in the lungs and airway, causing them to become reddened and swollen. Some scientists have referred to it as sunburn on the lining of the lung. The resulting damage:
  
  
• • Impairs lung function and can permanently damage the lungs
    
    
  • Can make health conditions such as asthma and allergies worse
    
    
  • May reduce the body’s ability to fight off bacterial infections

   

  According to the American Lung Association (ALA), nearly one-third of the U.S. population lives in an area with unsafe levels of ozone. High ozone levels account for almost all of the unhealthy air days nationwide.

• Particle pollution. Occurs when tiny particles enter the air from power plant emissions, diesel exhaust, wood burning and other sources. People can easily inhale these microscopic particles, which then penetrate the body’s defense system. Particle pollution has been linked to increased asthma, heart attacks, strokes, lung cancer and reduced life expectancy. According to the ALA, about one-third of the American population lives with unsafe short-term levels of particle pollution, and about 20 percent have unsafe year-round levels.
  
  
• Carbon monoxide. An odorless gas that reduces the oxygen-carrying capability of blood. It is the byproduct of indoor fuel-burning appliances such as gas stoves, gas or oil furnaces, fireplaces, wood stoves, and unvented kerosene or gas space heaters. Other combustion sources that create carbon monoxide include burning charcoal, gasoline engines running inside garages or sheds, unvented kerosene heaters and tobacco smoke.
  
  
• Nitrogen dioxide. An odorless gas that causes bronchial hyperresponsiveness (an exaggerated airway response). It is the byproduct of many of the same products that creat carbon monoxide, including indoor fuel-burning appliances such as gas stoves, gas or oil furnaces, fireplaces, wood stoves, and unvented kerosene or gas space heaters.
  
  
• Sulfur dioxide. A colorless gas with a pungent odor that can reduce lung capacity when inhaled over long periods of time. It is the byproduct of burning coal and oil at power plants and from copper smelting.

Many people find that exposure to pollutants triggers or worsens symptoms of respiratory ailments. These include:  

• Asthma. A chronic inflammation of the body’s bronchial (airway) tissues that afflicts millions of people in the United States. People with asthma experience shortness of breath, chest tightness, coughing and wheezing. These symptoms intensify during an asthma attack, which occurs when exposure to allergens or other stimuli further inflame the airways, leading to an inability to expel trapped air from the lungs. 
  
  Previously, it was thought that the presence of another allergen – such as pollen – was required to trigger asthma. A number of recent studies, however, have suggested that air pollutants alone can trigger asthma.

  

• Allergies.  An allergic reaction is the immune system’s attempt to defend the body from a perceived threat that, in reality, is harmless. Allergy symptoms can include itchy eyes, runny nose and sneezing. In some cases, the reaction is more extreme, resulting in hives, eczema (skin inflammation) or breathing difficulties. Pollution can increase symptoms in people with allergies.
  
  
• Chronic obstructive pulmonary disease (COPD). A combination of chronic bronchitis and emphysema that causes permanent damage to the air sacs (alveoli) and smaller bronchial tubes of the lungs. It tends to become progressively worse over time. Pollution can increase symptoms in people with COPD.
  
  
• Bronchitis. An inflammation in the lower airway of the respiratory system that can be allergic (caused by an allergic reaction) or nonallergic. Allergic bronchitis is also known as bronchial asthma or allergic asthma and shares the characteristics of asthmatic disease. Patients with allergic bronchitis need to avoid those allergens that trigger their symptoms. Pollution can increase symptoms in people with bronchitis.

Pollution is also known to cause other health problems, such as heart attacks, strokes, lung cancer, birth defects and reduced life expectancy. Symptoms that may be related to pollution include:

• Coughing
• Airway irritation
• Burning eyes
• Rapid, shallow or painful breathing
• Chest discomfort
• Wheezing
• Lung infections
• Poor coordination
• Fatigue
• Headache
• Confusion
• Nausea
• Dizziness

To date, there is no standard approach to diagnosing and treating pollution-related illnesses. A physician is likely to conduct a complete physical examination and compile a patient medical history and list of symptoms. Diagnosis and care is targeted toward the underlying condition that the pollution aggravates, such as asthma or a particular allergy.

A physician who suspects pollution to be a trigger for the underlying respiratory condition may also advise a patient to reduce their exposure to pollution. 

Although air pollution is potentially dangerous to many people, steps can be taken to reduce exposure to both indoor and outdoor pollutants.

Those affected by air pollution should make a habit of checking the Air Quality Index, a daily measurement of air-quality levels reported by the Environmental Protection Agency (EPA) that can be found at the department's Web site. Daily air quality data is also included in many local television and radio weather reports, as well as in newspapers. Five major pollutants are tracked:

• Ground-level ozone
• Particle pollution (particulate matter)
• Carbon monoxide
• Sulfur dioxide
• Nitrogen dioxide

Air quality for each pollutant is scored on a scale of 0 to 100, with various scores corresponding to a color that represents a level ranging from “good” to “hazardous.” Anything above 100 is considered unhealthy for those sensitive to pollution, including asthmatics and allergy sufferers. People sensitive to pollution should take the following precautions when air quality is poor:

• Limit time outdoors
• Reduce activity level
• Avoid using oil-based paints and solvents

Other general tips for those suffering from pollution illnesses include:

• Try to limit exercise or other strenuous outdoor activities to early morning or late evening, when air pollution levels tend to be lowest.
  
  
• Avoid exercising near busy roads or during rush hour, when pollution levels can be as much as 10 times higher than normal. Exercise involves deep inhalation, which brings pollutants more deeply into the lungs. Also, people tend to breathe through the mouth when exercising. Therefore, pollution in incoming air is not filtered the way it is when breathing through the nose.
  
  
• Reduce exposure to particle pollution by not allowing people to smoke in your home or car.
  
  
• Vent all gas or other combustion appliances directly to the outdoors.
  
  
• Do not burn wood or trash. 
  
  
• Do not use a gas stove or wood-burning stove to heat a home.
  
  
• Properly store and discard household paints, solvents and pesticides. These should be sealed in airtight containers.
  
  
• Use HEPA filters to capture airborne particles and common allergens in the home.
  
  
• Take steps to contribute to a less polluted environment. Walk, bike, carpool or use public transportation. Filling up gas tanks after dark, when gas vapors will not be able to react with sunlight, is also beneficial.
  
  
• Use hand-powered or electric lawn care equipment instead of gasoline-powered equipment. 

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to pollution:

1. Am I at higher risk for problems related to pollution exposure?
   
   
2. How will I know if I am being affected by pollution? What symptoms are commonly related to pollution exposure?
   
   
3. Are there tests available that can determine if I have lung or tissue damage caused by pollution?
   
   
4. What steps can I take to reduce my exposure to pollution?
   
   
5. Do we have a pollution problem in this area?
   
   
6. How can I find the daily air quality levels for the area?
   
   
7. How should I interpret the data from the Air Quality Index?
   
   
8. Should I limit the amount of time I spend outdoors?
   
   
9. Should I buy a HEPA filter for my home?
   
   
10. What effect does pollution have on my child’s respiratory health?