Indoor Pollutants

What are Combustion Pollutants?

Combustion pollutants are gases or particles that come from burning materials. The combustion pollutants discussed in this booklet come from burning fuels in appliances. The common fuels burned in these appliances are natural or LP gas, fuel oil, kerosene, wood, or coal. The types and amounts of pollutants produced depend upon the type of appliance, how well the appliance is installed, maintained, and vented, and the kind of fuel it uses. Some of the common pollutants produced from burning these fuels are carbon monoxide, nitrogen dioxide, particles, and sulfur dioxide. Particles can have hazardous chemicals attached to them. Other pollutants that can be produced by some appliances are unburned hydrocarbons and aldehydes.

Combustion always produces water vapor. Water vapor is not usually considered a pollutant, but it can act as one. It can result in high humidity and wet surfaces. These conditions encourage the growth of biological pollutants such as house dust mites, molds, and bacteria.

Where Do Combustion Pollutants Come From?

Combustion pollutants found indoors include: outdoor air, tobacco smoke, exhaust from car and lawn mower internal combustion engines, and some hobby activities such as welding, wood burning, and soldering. Combustion pollutants can also come from vented or unvented combustion appliances. These appliances include space heaters, gas ranges and ovens, furnaces, gas water heaters, gas clothes dryers, wood or coal-burning stoves, and fireplaces. As a group these are called "combustion appliances."

Nitrogen Dioxide:

Breathing high levels of nitrogen dioxide causes irritation of the respiratory tract and causes shortness of breath. Compared to healthy people, children, and individuals with respiratory illnesses such as asthma, may be more susceptible to the effects of nitrogen dioxide.

Some studies have shown that children may have more colds and flu when exposed to low levels of nitrogen dioxide. When people with asthma inhale low levels of nitrogen dioxide while exercising, their lung airways can narrow and react more to inhaled materials.

Sulfur Dioxide:

Sulfur dioxide at low levels of exposure can cause eye, nose, and respiratory tract irritation. At high exposure levels, it causes the lung airways to narrow. This causes wheezing, chest tightness, or breathing problems. People with asthma are particularly susceptible to the effects of sulfur dioxide. They may have symptoms at levels that are much lower than the rest of the population.

How Can I Reduce My Exposure to Combustion Pollutants?

Proper selection, installation, inspection and maintenance of your appliances are extremely important in reducing your exposure to these pollutants. Providing good ventilation in your home and correctly using your appliance can also reduce your exposure to these pollutants.

Additionally, there are several different residential carbon monoxide detectors for sale. The CPSC is encouraging the development of detectors that will provide maximum protection. These detectors would warn consumers of harmful carbon monoxide levels in the home. They may soon be widely available to reduce deaths from carbon monoxide poisoning.

Appliance Selection

• Choose vented appliances whenever possible.
• Only buy combustion appliances that have been tested and certified to meet current safety standards. Examples of certifying organizations are Underwriters Laboratories (UL) and the American Gas Association (AGA) Laboratories. Look for a label that clearly shows the certification.
• All currently manufactured vented gas heaters are required by industry safety standards to have a safety shut-off device. This device helps protect you from carbon monoxide poisoning by shutting off an improperly vented heater.
• Check your local and state building codes and fire ordinances to see if you can use an unvented space heater, if you consider purchasing one. They are not allowed to be used in some communities, dwellings, or certain rooms in the house.
• If you must replace an unvented gas space heater with another, make it a new one. Heaters made after 1982 have a pilot light safety system called an oxygen depletion sensor (ODS). This system shuts off the heater when there is not enough fresh air, before the heater begins producing large amounts of carbon monoxide. Look for the label that tells you that the appliance has this safety system. Older heaters will not have this protection system.
• Consider buying gas appliances that have electronic ignitions rather than pilot lights. These appliances are usually more energy efficient and eliminate the continuous low-level pollutants from pilot lights.
• Buy appliances that are the correct size for the area you want to heat. Using the wrong size heater may produce more pollutants in your home and is not an efficient use of energy.
• Talk to your dealer to determine the type and size of appliance you will need. You may wish to write to the appliance manufacturer or association for more information on the appliance. Some addresses are in the back of this booklet.
• All new woodstoves are EPA-certified to limit the amounts of pollutants released into the outdoor air. For more information on selecting, installing, operating, and maintaining wood burning stoves, write to the EPA Wood Heater Program. Their address is at the bottom of this booklet. Before buying a woodstove check your local laws about the installation and use of woodstoves.

About Wood Stoves

The burning of wood can produce asthma triggers. It is very important to make sure that wood stoves are properly installed, operated, and maintained to reduce leakage of by-products and to lower the risk for house fires. Check the following links for tips on using your wood stove safely.

Cockroaches

Droppings or body parts of cockroaches can be asthma triggers. Cockroaches are commonly found in crowded cities and the southern United States. Certain proteins, called allergens, are found in cockroach feces and saliva and can cause allergic reactions or trigger asthma symptoms in some individuals. Cockroach allergens likely play a significant role in asthma in many inner-city areas.

Actions You Can Take

An important key to pest management is to free your home of places for pests to hide and to keep them from food and water. Pesticides are toxic for people as well as pests; try to use pest management methods that present the least risk. Some of these methods are:

• Do not leave out food or garbage.
• Store food in airtight containers.
• Clean all food crumbs or spilled liquids right away.
• Wash dishes as soon as you are done using them.
• Keep counters, sinks, tables and floors clean and clear of clutter.
• Fix plumbing leaks and other moisture problems.
• Take piles of boxes, newspapers, and other items where cockroaches may hide out of your home.
• Make sure trash in your home is properly stored in containers with lids that close securely, and remove trash daily.
• Try using poison baits, boric acid, or traps first before using pesticide sprays.
• If sprays are used:
• Limit the spray to the infested area.
• Do not spray where you prepare or store food, or where young children play, crawl, or sleep.
• Carefully follow instructions on the label.
• Make sure there is plenty of fresh air when you spray, and keep the person with asthma out of the room while spraying. After spraying, the room should be thoroughly aired out.

What Are Dust Mites?

Dust mites are tiny animals you cannot see. Every home has dust mites. They feed on skin flakes and are found in mattresses, pillows, carpets, upholstered furniture, bedcovers, clothes, stuffed toys, and fabric or other fabric-covered items. Body parts and feces of dust mites can trigger asthma in individuals with an allergic reaction to dust mites. Exposure to dust mite allergen can cause asthma in susceptible children.

Actions You Can Take

Wash bedding (such as sheets, bedcovers, and blankets) once a week in hot water.
Choose washable stuffed toys, wash them often in hot water, and dry thoroughly. Keep stuffed toys off beds.
Cover mattresses and pillows in dust-proof (allergen-impermeable) zippered covers.
Maintain low indoor humidity ideally between 30-50% relative humidity. Humidity levels can be measured by hygrometers which are available at local hardware stores.

About Molds

Molds can be found almost anywhere; they can grow on virtually any substance when moisture is present. Outdoors, many molds live in the soil and play a key role in the breakdown of leaves, wood, and other plant debris. Without molds we would all be struggling with large amounts of dead plant matter. Molds break down plant materials by digesting them, using the plant material for food.

Molds produce tiny spores to reproduce, just as plants produce seeds. Mold spores waft through the indoor and outdoor air continually. When mold spores land on a damp spot indoors, they may begin growing and digesting whatever they are growing on in order to survive. There are molds that can grow on wood, paper, carpet, foods, even dynamite. When excessive moisture or water accumulates indoors, mold growth will often occur, particularly if the moisture problem remains undiscovered or unaddressed. There is no practical way to eliminate all mold and mold spores in the indoor environment; the way to control indoor mold growth is to control moisture.

Molds can trigger asthma episodes in individuals with an allergic reaction to mold.

Actions You Can Take

• If mold is a problem in your home, you must clean up the mold and eliminate sources of moisture.
• Wash mold off hard surfaces and dry completely. Absorbent materials, such as ceiling tiles and carpet, may have to be replaced if they are contaminated with mold.
• Fix leaky plumbing or other sources of water.
• Keep drip pans in your air conditioner, refrigerator, and dehumidifier clean and dry.
• Use exhaust fans or open windows in kitchens and bathrooms when showering, cooking, or using the dishwasher.
• Vent clothes dryers to the outside.
• Maintain low indoor humidity, ideally between 30-50% relative humidity. Humidity levels can be measured by hygrometers which are available at local hardware stores.

About Ozone

When inhaled, ozone can aggravate the lungs and can lead to chest pain, coughing, shortness of breath, and, throat irritation. Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections. On days when ozone air pollution is the highest, ozone air pollution has been associated with as much as ten percent (10%) to twenty percent (20%) of all summertime respiratory hospital visits and admissions.

People vary widely in their susceptibility to ozone. Healthy people, as well as those with respiratory difficulty, can experience breathing problems when exposed to ozone. Exercise during exposure to ozone causes a greater amount of ozone to be inhaled, and increases the risk of harmful respiratory effects.

Actions You Can Take

• State agencies will use television and radio to notify citizens of ozone alerts. On days when your State or local air pollution control agency calls an Ozone Action Day, people with asthma should limit prolonged physical activity outdoors. Consider adjusting outdoor activities to early in the morning or later in the evening.
• Also, on Ozone Action Days, you can do the following 10 things to help keep ozone formation to a minimum:
• Instead of driving, share a ride, walk or bike.
• Take public transportation.
• If you must drive, avoid excessive idling and jackrabbit starts.
• Don't refuel your car, or only do so after 7 p.m.
• Avoid using outboard motors, off-road vehicles, or other gasoline powered recreational vehicles.
• Defer mowing your lawn until late evening or the next day. Also avoid using gasoline-powered garden equipment.
• Postpone chores that use oil-based paints, solvents, or varnishes that produce fumes.
• If you are barbecuing, use an electric starter instead of charcoal lighter fluid.
• Limit or postpone your household chores that will involve the use of consumer products.
• Conserve energy in your home to reduce energy needs.

About Pets

Your pet’s dead skin flakes, urine, feces, saliva and hair can trigger asthma. Dogs, cats, rodents (including hamsters and guinea pigs) and other mammals all can trigger asthma in individuals with an allergic reaction to animal dander.

Proteins in the dander, urine, or saliva of warm-blooded animals (e.g., cats, dogs, mice, rats, gerbils, birds, etc.) have been reported to sensitize individuals and can cause allergic reactions or trigger asthma episodes in individuals sensitive to animal allergens. The most effective method to control animal allergens in the home is to not allow an animal in the home. If you remove an animal from the home, it is important to clean the home (including floors and walls, but especially carpets and upholstered furniture) thoroughly. Pet allergen levels are reported to stay in the home for several months after the pet is removed even with cleaning. Isolation methods to reduce animal allergen in the home have also been suggested by reputable health authorities (e.g., keeping the animal in only one area of the home, keeping the animal outside, or ensuring the allergic or asthmatic individual stay away from the animal) but the effectiveness of these methods have not been determined. To the contrary, several reports in the literature indicate that animal allergen is carried in the air and by residents of the home on their clothing to all parts of the home, even when the animal is isolated. In fact, animal allergen is often detected in locations where no animals were housed. In these situations, it is assumed that the allergen was carried in on people that have animals or on people that have been around animals or people with animals.

Often people sensitive to animal allergens are advised to wash their pets regularly. Recent research indicates that washing pets may only provide temporary reductions in allergen levels. There is no evidence that this short term reduction is effective in reducing symptoms and it has been suggested that during the washing of the animal the sensitive individual may be initially exposed to higher levels of allergen.

Thus the most effective method to control exposure to animal allergens is to keep your home pet free. However, some individuals may find isolation measures to be sufficiently effective. Isolation measures that have been suggested include keeping pets out of sleeping areas, keeping pets away from upholstered furniture, carpets, and stuffed toys, keeping the pet outdoors as much as possible, and isolating sensitive individuals from the pet as much as possible.

Actions You Can Take

• If pets are one of your asthma triggers, you need to strongly consider finding a new home from your pets.
• Keep pets out of the bedroom and other sleeping areas at all times, and keep the door closed.
• Keep pets away from fabric-covered furniture, carpets and stuffed toys.

Pollen

Many people are allergic to pollen, and pollen can be an asthma trigger. On high pollen days, stay indoors with the windows closed. Using your air conditioner may help to filter outside air coming into the home.

What Is Secondhand Smoke?

Secondhand smoke is also known as Environmental Tobacco Smoke. Secondhand smoke includes both exhaled mainstream smoke from smokers and side stream smoke from the end of a cigarette, cigar, or pipe. Secondhand smoke contains more than 4,000 substances, including over 40 that are linked to cancer. Many of the compounds in tobacco smoke are released at higher rates in side stream smoke than in mainstream smoke.

How Does Secondhand Smoke Relate To Asthma?

Secondhand smoke may trigger asthma episodes and make asthma symptoms more severe in children who already have asthma. Moreover, secondhand smoke is a risk factor for new cases of asthma in children who have not previously exhibited asthma symptoms.

The means by which secondhand smoke triggers an asthma episode is believed to be through its irritancy effects. That is, smoke irritates the chronically inflamed bronchial passages of asthmatics. This is a different pathway from most of the other environmental triggers of asthma, like dust mites and pet dander, which trigger asthma episodes through allergenic effects.

Exposure to secondhand smoke is also known to cause a variety of other negative health consequences, including lung cancer, ear infections in children, and respiratory illnesses.

Many of the health effects of secondhand smoke (including asthma) are most clearly manifested in children. This is because children are particularly vulnerable to secondhand smoke. This is likely due to several factors, including the fact that children are still developing physically, have higher breathing rates than adults, and have little control over their indoor environments. Children receiving high doses of secondhand smoke, such as those with smoking mothers, run the greatest relative risk of experiencing damaging health effects.

Sinusitis

You're coughing and sneezing and tired and achy. You think that you might be getting a cold. Later, when the medicines you've been taking to relieve the symptoms of the common cold are not working and you've now got a terrible headache, you finally drag yourself to the doctor. After listening to your history of symptoms and perhaps doing a sinus X-ray, the doctor says you have sinusitis.

Sinusitis simply means inflammation of the sinuses, but this gives little indication of the misery and pain this condition can cause. Chronic sinusitis, sinusitis that recurs frequently, affects an estimated 32 million people in the United States. Americans spend millions of dollars each year for medications that promise relief from their sinus symptoms.

Sinuses are hollow air spaces, of which there are many in the human body. When people say, "I'm having a sinus attack," they usually are referring to symptoms in one or more of four pairs of cavities, or spaces, known as Para nasal sinuses. These cavities, located within the skull or bones of the head surrounding the nose, include the frontal sinuses over the eyes in the brow area, the maxillary sinuses inside each cheekbone, the methods just behind the bridge of the nose and between the eyes, and behind them, the sphenoid in the upper region of the nose and behind the eyes.

Each sinus has an opening into the nose for the free exchange of air and mucus, and each is joined with the nasal passages by a continuous mucous membrane lining. Therefore, anything that causes a swelling in the nose-an infection or an allergic reaction-also can affect the sinuses. Air trapped within an obstructed sinus, along with pus or other secretions, may cause pressure on the sinus wall. The result is the sometimes intense pain of a sinus attack. Similarly, when air is prevented from entering a Para nasal sinus by a swollen membrane at the opening, a vacuum can be created that also causes pain.

Symptoms

Sinusitis has its own localized pain signals, depending upon the particular sinus affected. Headache upon awakening in the morning is characteristic of sinus involvement. Pain when the forehead over the frontal sinuses is touched may indicate inflammation of the frontal sinuses. Infection in the maxillary sinuses can cause the upper jaw and teeth to ache and the cheeks to become tender to the touch. Since the ethmoid sinuses are near the tear ducts in the corner of the eyes, inflammation of these cavities often causes swelling of the eyelids and tissues around the eyes and pain between the eyes. Ethmoid inflammation also can cause tenderness when the sides of the nose are touched, a loss of smell, and a stuffy nose. Although the sphenoid sinuses are less frequently affected, infection in this area can cause earaches, neck pain, and deep aching at the top of the head.

Other symptoms of sinusitis can include fever, weakness, tiredness, a cough that may be more severe at night, and runny nose or nasal congestion. In addition, drainage of mucus from the sphenoid down the back of the throat (postnasal drip) can cause a sore throat and can irritate the membranes lining the larynx (upper windpipe).

Causes

Most cases of acute sinusitis are caused by viruses and will clear up without treatment within two weeks. Viruses can enter the body through the nasal passages and set off a chain reaction resulting in sinusitis. For example, the nose reacts to an invasion by viruses that cause infections such as the common cold, flu, or measles by producing mucus and sending white blood cells to the lining of the nose, which congest and swell the nasal passages. When this swelling involves the adjacent mucous membranes of the sinuses, air and mucus are trapped behind the narrowed openings of the sinuses. If the sinus openings become too narrow to permit drainage of the mucus, then bacteria, which normally are present in the respiratory tract, begin to multiply. Most apparently healthy people harbor bacteria, such as Streptococcus pneumoniae and Haemophilus influenza, in their upper respiratory tracts with no ill effects until the body's defenses are weakened or drainage from the sinuses is blocked by a cold or other viral infection. The bacteria that may have been living harmlessly in the nose, throat, or sinus area can multiply and cause an acute sinus infection.

Medicines, too, can set off a nasal reaction with accompanying sinusitis. For example, intolerance to aspirin and other related non-steroidal anti-inflammatory medications, such as ibuprofen, can be associated with sinusitis in patients with asthma or nasal polyps (small growths on the mucous membrane lining of the sinuses).

Sometimes, fungal infections can cause acute sinusitis. Although these organisms are abundant in the environment, they usually are harmless to healthy people, indicating that the human body has a natural resistance to them. Fungi, such as Aspergillus and Curvularia, can cause serious illness, in people whose immune systems are not functioning properly. Some people with fungal sinusitis have an allergic-type reaction to the fungi.

Chronic inflammation of the nasal passages (rhinitis) also can lead to sinusitis. Allergic rhinitis or hay fever (discussed below) is the most common cause of chronic sinusitis and is a frequent cause of acute sinusitis. Vasomotor rhinitis, caused by humidity, cold air, alcohol, perfumes, and other environmental conditions, also can result in a sinus infection.

Chronic Sinusitis

Chronic sinusitis refers to inflammation of the sinuses that continues for weeks, months, or even years. As noted above, allergies are the most common cause of chronic sinusitis. Inhalation of airborne allergens (foreign substances that provoke an allergic reaction), such as dust, mold, and pollen, often set off allergic reactions (allergic rhinitis) that, in turn, may contribute to sinusitis. People who are allergic to fungi can develop a condition called "allergic fungal sinusitis." As body cells react against these inhaled substances, they release chemical compounds, such as histamine, at the mucosal surface. These chemicals then cause the nasal passages to swell and block drainage from the sinuses, resulting in sinusitis.

Damp weather, especially in northern temperate climates, or pollutants in the air and in buildings also can affect people subject to chronic sinusitis.

Chronic sinusitis can be caused by structural abnormalities of the nose, such as a deviated septum (the bony partition separating the two nasal passages), or by small growths called nasal polyps, both of which can trap mucus in the sinuses.

Diagnosis

Although a stuffy nose can occur in other conditions, like the common cold, many people confuse simple nasal congestion with sinusitis. A cold, however, usually lasts about seven days and disappears without treatment. Acute sinusitis often lasts longer than a week. A doctor can diagnose sinusitis by medical history, physical examination, X-rays, and if necessary, MRIs or CT scans (magnetic resonance imaging and computed tomography).

Treatment

After diagnosing sinusitis and identifying a possible cause, a doctor can prescribe a course of treatment that will clear up the source of the inflammation and relieve the symptoms.

Sinusitis is treated by re-establishing drainage of the nasal passages, controlling or eliminating the source of the inflammation, and relieving the pain. Doctors generally recommend decongestants to reduce the congestion, antibiotics to control a bacterial infection, if present, and pain relievers to reduce the pain.

Over-the-counter and prescription decongestant nose drops and sprays, however, should not be used for more than a few days. When used for longer periods, these drugs can lead to even more congestion and swelling of the nasal passages.

If symptoms do not improve within 10 to 14 days, the cause of sinusitis is likely to be bacterial. Most patients with sinusitis that is caused by bacteria can be treated successfully with antibiotics used along with a nasal or oral decongestant. A narrow-spectrum antibiotic -- one that fights the most common bacteria -- is the initial treatment recommended.

For many years, the combination of allergic disease and infectious sinusitis has been considered the most difficult form of sinus disease to treat. The patient with uncontrolled nasal allergies frequently experiences a lot of congestion, swelling, excess secretions, and discomfort in the sinus areas. Therefore, the patient should work with a doctor who understands the diagnosis and treatment of allergic diseases to pinpoint the cause of the allergies and follow an allergy care program to help alleviate sinusitis.

Doctors often prescribe steroid nasal sprays, along with other treatments, to reduce the congestion, swelling, and inflammation of sinusitis. Because steroid nasal sprays have no serious side effects, they can be used for long-term treatment. In some people, however, they irritate the nasal passages.

For patients with severe chronic sinusitis, a doctor may prescribe oral steroids, such as prednisone. Because oral steroids can have significant side effects, they are prescribed only when other medications have not been effective.

Although sinus infection cannot be cured by home remedies, people can use them to lessen their discomfort. Inhaling steam from a vaporizer or a hot cup of water can soothe inflamed sinus cavities. Another treatment is saline nasal spray, which can be purchased in a pharmacy. A hot water bottle; hot, wet compresses; or an electric heating pad applied over the inflamed area also can be comforting.

In treating patients with severe sinusitis, a physician may use special procedures. One technique requires the patient to lie on his back with his head over the edge of the examining table. A decongestant fluid is placed in the nose, and air is suctioned out of the nose so that the decongestant fluid can shrink the sinus membranes sufficiently to permit drainage. Or, a thin tube can be inserted into the sinuses for washing out entrapped pus and mucus.

Sometimes, however, surgery is the only alternative for preventing chronic sinusitis. In children, problems often are eliminated by removal of adenoids obstructing nasal-sinus passages. Adults who have had allergic and infectious conditions over the years sometimes develop polyps that interfere with proper drainage. Removal of these polyps and/or repair of a deviated septum to ensure an open airway often provides considerable relief from sinus symptoms. The most common surgery done today is functional endoscopic sinus surgery, in which the natural openings from the sinuses are enlarged to allow drainage.

Prevention

Although people cannot prevent all sinus disorders-any more than they can avoid all colds or bacterial infections-they can take certain measures to reduce the number and severity of the attacks and possibly prevent sinusitis from becoming chronic. Appropriate amounts of rest, a well-balanced diet, and exercise can help the body function at its most efficient level and maintain a general resistance to infections. Eliminating environmental factors, such as climate and pollutants, is not always possible, but they can often be controlled.

Many people with sinusitis find partial relief from their symptoms when humidifiers are installed in their homes, particularly if room air is heated by a dry forced-air system. Air conditioners help to provide an even temperature, and electrostatic filters attached to heating and air conditioning equipment are helpful in removing allergens from the air.

A person susceptible to sinus disorders, particularly one who also is allergic, should avoid cigarette smoke and other air pollutants. Inflammation in the nose caused by allergies predisposes a patient to a strong reaction to all irritants. Drinking alcohol also causes the nasal-sinus membranes to swell.

Sinusitis-prone persons may be uncomfortable in swimming pools treated with chlorine, since it irritates the lining of the nose and sinuses. Divers often experience congestion with resulting infection when water is forced into the sinuses from the nasal passages.

Air travel, too, poses a problem for the individual suffering from acute or chronic sinusitis. A bubble of air trapped within the body expands as air pressure in a plane is reduced. This expansion causes pressure on surrounding tissues and can result in a blockage of the sinuses or the Eustachian tubes in the ears. The result may be discomfort in the sinus or middle ear during the plane's ascent or descent. Doctors recommend using decongestant nose drops or inhalers before the flight to avoid this difficulty.

People who suspect that their sinus inflammation may be related to dust, mold, pollen, or food-or any of the hundreds of allergens that can trigger a respiratory reaction-should consult a doctor. Various tests can determine the cause of the allergy and also help the doctor recommend steps to reduce or limit allergy symptoms.
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NIAID, a component of the National Institutes of Health, supports research on AIDS, tuberculosis and other infectious diseases as well as allergies and immunology.

Prepared by:
Office of Communications and Public Liaison
National Institute of Allergy and Infectious Diseases
National Institutes of Health
Bethesda, MD 20892

Public Health Service
U.S. Department of Health and Human Services
June 1998