Identifying and reducing exposure to allergens and irritants that exacerbate asthma is a key component in treating the disease
The Merriam-Webster Collegiate Dictionary defines the environment as “the complex of physical, chemical, and biotic factors (such as climate, soil, and living things) that act upon an organism.” Indeed, individuals with asthma may be affected by a wide range of triggers found in their daily environment. Identifying and reducing exposure to such allergens and irritants is a key component of the recommendations contained in the Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma1 issued by the National Institutes of Health in 1997.
Mechanisms of Asthma
The chronic inflammation of asthma causes an associated increase in a preexisting bronchial hyper-responsiveness to a variety of stimuli. The majority of these stimuli are believed to be environmental factors.2
It does appear that there is a genetic predisposition for asthma: in families with one parent who has asthma, there is a 28% chance of having at least one asthmatic child. Families with two asthmatic parents have a 63% chance that one of their children will have asthma.3 The genetically inherited tendency to develop allergies is called atopy, considered to be the most important predictor for a person to develop asthma.4 It is estimated that allergies occur in 90% of children with asthma under 16 years of age, 70% of adults under 30, and 50% of adults over 30.3 These individuals show an increased level of immunoglobulin (IgE) antibodies in their blood.
Triggers
Successful asthma management depends on a combination of careful diagnosis, effective medications, and identifying and controlling exposure to factors that result in asthma exacerbation. The National Asthma Education and Prevention Program (NAEPP) Guidelines1 identify the following four categories of asthma triggers:
• Inhalant allergens such as animal allergens, house-dust mites, cockroach allergens, indoor fungi and molds, and outdoor allergens;
• Occupational exposures such as dusts, fumes, and gases;
• Irritants such as tobacco smoke and indoor/outdoor pollution;
• Other factors such as rhinitis/sinusitis, gastro-esophageal reflux, sensitivity to certain medications, and viral respiratory infections.
Does environmental control really work to reduce asthma episodes? If so, why don’t more patients implement this strategy? Paul A. Selecky, MD, medical director of the Pulmonary Department at Hoag Memorial Hospital, Newport Beach, Calif, and medical advisor for the Continuing Care/Rehabilitation Specialty Section of the American Association for Respiratory Care, says, “Many patients (and doctors) forget about this piece of the asthma puzzle and continually go to their rescue medication when they experience asthma symptoms. If they don’t take steps to eliminate triggers from their home environment, their airways stay constantly inflamed, and they will experience asthma attacks that may become more frequent as well as more serious as time passes.” Selecky states, “The key is education of the patient and their family. Respiratory therapists working with these patients should be questioning them closely and specifically about their environment and symptoms and then educating them about environmental control. This is essential for successful asthma management.”
The Indoor Home Environment
The incidence of asthma in the United States increased by 75% between 1980 and 1994 and the incidence in children more than doubled.5 It is probable that changes in the American lifestyle are responsible for a good proportion of this increase.
When the cost of energy escalated dramatically in the 1970s and early 1980s, a trend developed to build more energy-efficient homes and other buildings. These tightly sealed buildings with more insulation and double-paned windows help to keep the ambient air comfortable at a reduced energy cost, but they also reduce natural air exchange and ventilation. This allows for a greater buildup of harmful substances in the indoor environment such as radon, tobacco smoke, biological contaminants, pesticides, formaldehyde, and carbon monoxide. Other factors include the advent of central heating, wall-to-wall carpeting, and new chemicals used in building supplies and household items.
The amount of time Americans spend indoors has also increased. A study commissioned by the Environmental Protection Agency6 (EPA) revealed that most adults in the United States spend 90% of their time indoors. Children spend far less time playing outdoors than they did in past decades. Increased time in day care plus the advent of computers, video games, and other indoor activities have increased the amount of time children spend indoors today. All of these factors help to increase the potential exposure of asthma patients to known asthma triggers.
A recent study published in Pediatrics revealed some dramatic information about the importance of indoor environmental control. Lanphear et al7 collected data from 5,384 children aged 6 to 16 years over a period of 6 years. Through parent questionnaires and skin testing, 11.4% of the children were identified with doctor-diagnosed asthma. Their study demonstrated that exposure to indoor environmental risk factors accounted for 44.4% or an estimated 2 million excess cases of asthma. They believe that the elimination of identified indoor asthma triggers would result in a 44% decline in doctor-diagnosed asthma cases in this population.
The following information lists some of the well-known indoor environmental risk factors for asthma and steps that can be taken to reduce exposure to these factors:
Dust Mites
Dust mites are microscopic insects that thrive in the home environment and are one of the most common asthma triggers. They feed on the skin cells shed by humans and are particularly fond of carpeting, bedding, mattresses, upholstered furniture, and stuffed toys. The following steps can help to reduce the dust mite population:
• Cover mattresses, box springs, and pillows with dust-proof covers;
• Buy nonallergenic sheets and blankets and pillows for your bedroom;
• Wash sheets and bedding weekly in hot water (greater than 130°F) and adding bleach to the wash will help as well;
• Eliminate carpeting from the home, choosing washable surfaces such as hardwood floors or vinyl flooring, and damp mop them regularly. At the very least, try to eliminate carpeting in the bedroom and over any cement floors. Washable area rugs may be used;
• Remove decorative items such as stuffed toys and pillows. There are some nonallergenic stuffed toys available that are washable;
• “Wipeable” furniture is preferable to upholstered furniture. Wood, plastic, vinyl, and leather are all good choices;
• Utilize washable window shades or curtains in place of miniblinds or drapes, and clean them frequently;
• Keep unused clothing in plastic garment bags and keep closet doors closed;
• Utilize HEPA filters for heating and cooling systems;
• HEPA vacuum cleaners can reduce dust mites. A dust mask may be used as well; and
• Keeping the home humidity at 50% or less through the use of dehumidifiers or air conditioners will eliminate most dust mites.
Pets
All furred and feathered pets can cause an asthma reaction in sensitive individuals. This reaction is due to a protein found in particles of skin, urine, and saliva known collectively as dander. These allergens can remain in the home for up to 6 months after a pet is removed. Some suggestions for control of animal triggers are:
• Remove furry and feathered pets from the home. Pets with fins and scales are much more asthma-friendly;
• Keep any beloved pets outside or, at the very least, out of the bedroom;
• Wash pets weekly (even cats) to reduce the dander level; and
• Clean regularly.
Cockroaches
Cockroaches and their waste products are significant asthma triggers. There is a strong link between the increasing numbers of inner-city children with asthma and cockroach sensitivity.8 Suggestions for better control are:
• Store all food in sealed containers;
• Wash dishes and silverware immediately after use;
• Clean up any food crumbs from counters, tables, floors, and furniture;
• Keep garbage cans well-sealed and remove household garbage promptly; and
• Seal holes around pipes, windows, doors, and baseboards to prevent entry into the home.
Molds and Other Fungi
Molds release their spores into the air and are inhaled, causing asthma symptoms. They are frequently found in dark, damp, or poorly ventilated areas and can be behind the wall coverings in some homes.
• Use exhaust fans to reduce moisture in bathrooms;
• Eliminate carpets in bathrooms or basements;
• Use paint instead of wallpaper especially if the humidity is high;
• Use dehumidifiers or air conditioners to reduce the humidity level;
• Clean surfaces where mold grows such as under the sink and around the refrigerator with disinfectant cleansers; and
• Reduce the number of houseplants and keep them in plastic pots.
Tobacco Smoke
The relationship between environmental tobacco smoke and asthma is well established. Studies show that maternal smoking during pregnancy doubles the risk of having asthma and that smoking in the home results in a higher percentage of asthma in the children living there.5
• Never allow smoking anywhere in the home or anywhere near an asthmatic; and
• Adults should ask for assistance from their health care provider to help stop smoking.
Nitrogen Dioxide
Nitrogen dioxide comes mainly from gas stoves or from space heaters, and has been shown to be related to the incidence of asthma episodes in several studies. A study by Ng et al9 showed that women using gas stoves for cooking recorded immediate falls in peak flow rates. When exposed consistently over a 2-week period, they reported a significant increase in reliance on inhaled bronchodilators.
• Make sure gas stoves are adequately vented and use an exhaust fan if possible;
• Utilize electric heaters rather than space heaters for warmth in the home; and
• Avoid using wood stoves or fireplaces.
Chemical Irritants
Significant chemical irritants are found in paints, plastics, carpeting, detergents, and cleaning supplies. Some items such as particleboard contain large amounts of formaldehyde, which can trigger significant asthma attacks.10
• Avoid these products when at all possible;
• Choose fragrance-free products for household use;
• Keep all areas well ventilated in the home; and
• Avoid perfumes, aerosols, talc, air fresheners, and other products emitting strong odors or fumes.
The School Environment
Nearly 55 million people (20%) of the United States population attend our nation’s schools. Studies have shown that a full one-half of these schools have problems linked to indoor air quality.11 The EPA is spearheading a national effort to improve the indoor air quality in American schools, thereby increasing school attendance and student performance. It has initiated the “Indoor Air Quality: Tools for Schools” program, which includes complete action plans and checklists for school administrators, teachers, parents, and community members to improve the indoor air quality at their schools. Copies of the program are available from regional EPA offices and workshops, or may be downloaded from its Web site at www.epa.gov/iaq/schools.
Some of their basic recommendations to improve the school environment are:
• Ensure that an adequate amount of outdoor air is being supplied;
• Test for radon;
• Separate students and staff from construction and renovation areas;
• Reduce use of products such as adhesives, floor-care products, and pesticides that require ventilation during use;
• Clean up mold and control moisture, maintaining relative humidity at a level below 60% indoors;
• Remove furry and feathered animals from the classroom;
• Control exposures to cockroach and dust mite allergens;
• Eliminate secondhand smoke exposure; and
• Develop an asthma management plan for the school that includes school-based asthma education programs, student asthma action plans, and a library of asthma information and resources.
The Occupational Environment
Work-related asthma is a leading cause of occupational respiratory disorders and accounts for approximately 2% of all asthma cases.12 Occupational asthma may be characterized by immediate symptoms in reaction to high levels of irritants or by asthma present after a latent period following continuing exposure to the causative factors.
Some of the factors associated with occupational asthma are chemical dusts or vapors from plasticizers, polyurethane paints, insulation, upholstery, and packaging materials used in manufacturing processes. Persons working as farmers, veterinarians, and others working with animals may be exposed to animal substances such as hair, dander, mites, or bacterial elements. Food processors may be exposed to organic dusts such as flour, cereals, and grains. Textile workers are exposed to cotton, flax, and other organic dusts. Metals such as platinum chromium, and nickel sulfate, and soldering fumes, are asthma triggers and refinery workers are exposed to dangerous fumes as well. There are various methods that might be tried to reduce occupational exposures, which include:
• Adequate ventilation in all work areas;
• Upgrading hygiene techniques, engineering controls, and work practices;
• Personal protection such as respirators, masks, and air hoods;
• Periodic medical surveillance of potentially affected workers; and
• Change occupation or job duties if asthma cannot be controlled.
The Outdoor Environment
The urbanization of America presents a number of dangers to a healthy lifestyle, especially in terms of asthma. A number of factors found in the outdoor environment can act as asthma triggers. Some of these include pollen and mold spores; extreme weather conditions such as wind, storms, and cold air; and air pollution from smoke, smog, car exhaust, and industrial pollutants.
Pollens and Molds
In the spring, summer, and fall, pollens are released from trees, weeds, and grasses. These common asthma triggers vary in amount by season, geographic location, and weather conditions. Pollen counts are frequently higher on the sunny and warm days of summer. Mold spores are more prevalent during damp weather. To minimize these asthma triggers:
• Check the local pollen count. It is readily available from the newspaper, health department, weather service, or Internet;
• Take prescribed medications when pollen count or mold growth is high;
• Keep windows closed, and limit outdoor exposure between 5 am and 10 am when pollen counts are highest because of rapidly rising temperatures;
• Wear a pollen or dust mask when working in the yard and garden;
• Keep the landscaping around a home pruned back with minimal ground vegetation and weeds;
• Keep the yard raked, avoiding piles of damp leaves or mulch, and bark-type mulches.
• When walking, stay away from highways and roads where fast-moving vehicles can stir up road dust that contains pollens and spores. When driving, keep the windows up and the air conditioner running. This acts as a filter against automobile exhaust exposure as well; and
• Shower and wash hair every night to remove pollen and keep it from getting on the pillow.
Weather
Many people with asthma report that they experience a flare-up of their asthma symptoms when the weather changes. Dry, cold air can be very difficult for many people with asthma, frequently leading to bronchospasm and wheezing. Unfortunately, hot humid weather can also lead to asthma symptoms in some patients, possibly related to increased mold growth at those temperatures. Windy days can cause problems for asthmatics since mold spores, pollens, and dusts can be difficult to avoid. Many people report an increase in asthma symptoms during thunderstorms. The mechanisms for this are not completely clear, although one factor may be the increase in atmospheric ozone generated during thunderstorms since ozone is a known asthma irritant. For people who experience weather-related asthma symptoms, the following may be of help:
• Keep a diary that tracks weather changes to try to identify asthma patterns;
• Limit exertion in cold, dry air;
• Wear a scarf or mask over the nose and mouth when outside during cold weather;
• Stay indoors with the windows closed during bothersome weather phenomena such as storms or high winds;
• Be aware of poor air quality days that result from stagnant air. These are most likely to occur during hot summer months; and
• Keep a rescue inhaler close at hand to treat flare-ups of asthma symptoms.
Air Pollution
Air pollution is a fact of life in today’s world, the side effect of global industrialization and urbanization. Kent Bransford, MD, member of the National Board of Directors for Physicians for Social Responsibility, Washington, DC, explains that the earth “is a closed system; nothing gets out.” He states that “today’s greenhouse gases, heavy metals, and other persistent compounds accumulate as they are produced in greater quantities than nature can absorb… it’s like smoking in a closed room.” Today’s cities harbor millions of people and machines. Gas and diesel engines, as well as industrial pollutants, result in a haze of smog hanging over most major cities in the United States and around the world. Ozone, nitrogen dioxide, sulfur dioxide, and particulate matter are the main forms of air pollution in our outdoor environment. These oxidizing gases are formed as by-products of combustion, and can cause airway inflammation in humans, whether or not they have asthma. Since the level of ozone and pollutants increases as temperatures increase, the phenomenon of global warming promises to make this a continuing problem.
Increasing numbers of studies document the connection between air pollution and asthma. Increased levels of ozone and nitrogen dioxide result in a rise in asthma hospital admissions and emergency department visits.13 Unfortunately, 25% of all American children live in areas that exceed the federal government’s standard for ozone.14 An interesting study by Friedman et al15 described the effects of a traffic reduction plan in effect during the 2000 Summer Olympic Games in Atlanta. They found that during this 17-day period, peak daily ozone levels were reduced 28%, particulates 15%, and carbon dioxide 18%. At the same time, asthma treatments recorded at area hospitals, clinics, and physician offices decreased by 44.1%.
One of the most worrisome pollutants is the particulate matter generated by diesel combustion. One problem with diesel particulate matter is that it frequently is of a size that is not currently regulated by federal air quality standards. In addition, they can significantly increase the body’s capacity to produce IgE antibodies, making an asthmatic more responsive to other allergens and even cause people who are not normally sensitive to certain triggers to react to these factors.13 Todd Campbell, MPP, policy director for the Coalition for Clean Air in California, is alarmed that diesel power is becoming increasingly popular as an energy source. “This is a form of energy that has traditionally been used as an emergency source for peak periods. This year’s energy crisis has seen diesel power used far more by businesses and individuals for ordinary power needs.” He continues, “This is very significant since diesel combustion produces 131 times more smog-forming pollutants than today’s traditional combined-cycle power plants.” He adds that “the lifetime cancer risk is increased by 50% in individuals who live near a one megawatt diesel generator run for only 250 hours per year; that’s only 10.4 days per year.”
Children seem to pay the highest price for the increase in air pollution in certain areas. The ongoing Children’s Health Study, sponsored by the California Air Resources Board, the National Institute of Environmental Health Sciences, and the EPA is following children in high and low air pollution areas in Southern California over a 10-year period. After 4 years, preliminary results show an increased level of asthma and bronchitis in the high-pollution areas as well as a comparative loss of lung function at a rate of 1% per year.16
Opportunities for RTs
Andrea Van Hook is vice president of communications for the American Lung Association (ALA) of Los Angeles County. She states that RTs can play a key role in protecting Americans with asthma and other respiratory problems from dangerous environmental exposures. Van Hook says, “We use respiratory therapists as facilitators for many of our community programs to educate children, parents, and others about asthma control.” She notes that “many respiratory therapists across the country go into schools with the ALA ‘Open Airways’ programs for grades three, four, and five. The children, teachers, and parents can learn how to modify their environment to minimize asthma episodes at home and at school.” She lists other opportunities “such as the ‘Little Lungs Program’ for ages 0-5, and the ‘A Is for Asthma’ program that works with preschoolers.” Van Hook goes on to note that “respiratory therapists are ideally suited for this type of patient education.” In Los Angeles County, “we invite respiratory therapists to take our media training, so they can serve as ‘experts’ for our legislative network and other forums on health and air quality issues.” She states that one of the most important things to teach asthmatics is “to know about the air quality index and other ways to protect themselves from environmental triggers.” The Air Quality Management Board and the ALA in Los Angeles and other communities have alert systems in place for use by individuals at high risk.
Aftermath Of Tragedy
The tragic events of September 11, 2001, may have added long-term adverse health effects on asthmatics and others with respiratory problems in the city of New York. The billowing clouds of dust, smoke, and ash have caused a large increase in respiratory problems in the area. The smoke from the World Trade Center contains gypsum, concrete, wallboard particles, asbestos, diesel smoke from the jet fuel, and other unknown toxic materials. Prolonged exposure, especially in the rescue workers, could have serious long-term effects. The EPA has both monitoring equipment and heavy-duty filtration systems in place to help alleviate problems stemming from the attacks and subsequent cleanup.
Van Hook would like everyone in the respiratory community to be aware that the ALA of New York has established a “9-1-1 Respiratory Assistance Fund” to provide information, resources, financial assistance, equipment, and respiratory medications to victims of the September 11 attack. Those wishing to assist in these efforts can contact the ALA of New York. Financial donations can be forwarded through most local ALA chapters.
Peggy Walker, RRT, RCP, is the Western Regional Liaison Representative for the Asthma and Allergy Support Center, Los Angeles.
References
1. Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma. Bethesda, Md: NIH/NHLBI; 1997.
2. Wray BB. Taking Charge of Asthma: A Lifetime Strategy. New York: John Wiley and Sons Inc; 1998.
3. Adams PF, Marano MA. Current estimates from the National Health Interview Survey, 1994. Vital Health Statistics. 1995;10:94.
4. Hopkin JM. Mechanisms of enhanced prevalence of asthma and atopy in developed countries. Curr Opin Immunol. 1997;9:778-792.
5. Mannino DM, Homa DM, Pertowski, CA, et al. Surveillance for asthma—United States, 1960-1995. MMWR Morb Mortal Wkly Rep. 1998;47:S1-S28.
6. Johnston RB, Burge HA, Fisk WJ, et al. Clearing the Air: Asthma and Indoor Air Exposures. Report from the Committee on the Assessment of Asthma and Indoor Air. Institute of Medicine. Washington, DC: National Academy Press; 2000.
7. Lanphear BP, Kahn RS, Berger O, et al. Contribution of residential exposures to asthma in U.S. children and adolescents. Pediatrics. 2001;107:E98.
8. Kattan M, Mitchell H, Eggleston P, et al. Characteristics of inner city children with asthma: the National Cooperative Inner-City Asthma Study. Pediatr Pulmonol. 1997;24:253-262.
9. Ng TP, Seet CS, Tan WC, et al. Nitrogen dioxide exposure from domestic gas cooking and airway response in asthmatic women. Thorax. 2001;56:596-601.
10. NSW Health Department. Asthma and the Environment: Perspectives on the Prevention of Asthma. Sydney, Australia: NSW Health Department Publication 970089; 1997.
11. Daisey JM, Angell WJ. Indoor quality, ventilation and health symptoms in schools: an analysis of existing information. In: Proceedings, Eighth International Conference on Indoor Air Quality and Climate: Indoor Air ‘99, Edinburgh (Scotland), 1999.
12. Reinish F, Harrison RJ, Cussler S, et al. Physician reports of work-related asthma in California, 1993-1996. Am J Ind Med. 2001;39:72-83.
13. Koren HS. Associations between criteria air pollutants and asthma. Environ Health Perspect. 1995;103:S253-S271.
14. Centers for Disease Control and Prevention. Children at risk from ozone air pollution—United States, 1991-1993. CDC Surveill Summ. 1995;44;309-312.
15. Friedman MS, Powell KE, Hutwagner L, et al. Impact of changes in transportation and commuting behaviors during the 1996 summer Olympic games in Atlanta on air quality and childhood asthma. JAMA. 2001;258:897-905.
16. Gauderman WJ, McConnell R, Gilliland F, et al. Association between air pollution and lung function growth in Southern California children. Am J Respir Crit Care Med. 2000;162:1383-1390.
