Setting Expectations For Reducing Asthma Triggers

Asthma is a chronic lung disease that affects more than 17 million U.S. residents.1 The management of asthma incorporates pharmacotherapy, trigger avoidance and allergen reduction. Asthma exacerbations occur at any time and result from triggers including allergens, irritants such as tobacco smoke or strong odors, changes in weather, infections, exercise, acid reflux disease, medications, and foods.

This article outlines current allergen reduction recommendations, the impact of those reduction strategies on the families of asthma patients, the efficacy of these strategies, and implications for health care providers.

The National Heart, Lung and Blood Institute and its National Asthma Education and Prevention Program (NAEPP) recently released a document titled “Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma.” These guidelines refine the classifications of asthma and outline recommended medication management for each asthma class.2

In addition to medication management, comprehensive treatment of the asthma patient must include a review of recommended environmental control methods to reduce allergens.

Successful reduction of environmental allergens requires a collaborative and achievable plan. Individually tailored plans are necessary because required modifications might be unacceptable or impractical to implement.

Factors to consider include the availability of time for cleaning and laundering; the expense of air filtration units, vacuums and mattress covers; the feasibility of moisture control; and the importance of the family pet.

Guidelines and Research

Meeting current recommendations to decrease environmental allergens is labor and time intensive. These measures often require the asthma patient and his or her family to change habits and home surroundings.

The NAEPP recommends starting by identifying patient-specific allergens through the use of allergy diaries or testing.2

Once specific triggers are identified, environmental changes can be tailored to each patient. A list of recommended environmental changes from the American Lung Association (ALA) and the American Academy of Allergy, Asthma and Immunology (AAAAI) are listed in Table 1.3,4 When consistently followed, these recommendations create the ideal home environment.

Many studies have sought to test these recommendations, and the results have varied. Researchers have used a variety of methods to test asthma severity and allergen levels in the home. For example, asthma severity has been measured by variables such as emergency department visits, FEV1, FVC, medication use, and self-reporting of daytime and nighttime symptoms. This variation makes comparisons among studies difficult.

Few studies have looked at the effects of individual interventions because most studies combine several interventions. Studies have shown that multiple interventions aimed at reducing several sources of allergens provide the most noticeable results.2 But without studies investigating single interventions, it is hard to distinguish whether any intervention performs better than others.2

Family Impact

Following recommendations to reduce environmental allergens requires time, money and effort. Incorporating these changes can have a significant impact on families, who may view asthma and its management as a burden. Obtain a thorough picture of how such changes might affect a patient’s family.

Studies have shown that the amount of time families spend cleaning and doing laundry has decreased. In 1965, families spent an average of 27 hours per week on household chores.5 In 1995, families spent an average of 15.6 hours weekly on household chores.5 And a study performed in 2000 found that families spent an average of 12.7 hours weekly on these activities.6

Unfortunately, none of these studies included a comparison of how many times the average household dusted or vacuumed each week or how often bedding was washed per week. Whether time spent on housework has declined because of increased productivity from technology or from less household chore performance in general is unknown. One implication derived from these studies is that time available for housework has decreased due to multiple time commitments of family members.5 The findings further emphasize the need for allergen control measures that require minimal time and effort.

Air Filtration Systems

The ALA and the AAAAI state that air filtration units may be useful, but these organizations acknowledge that their effectiveness has not been proven.3,4 Despite this lack of evidence, U.S. residents spend more than $350 million annually on these products.7

An analysis by the Environmental Protection Agency (EPA) found that most allergens tend to settle rapidly out of the air onto surfaces. Effectiveness of air filters is limited because allergen concentrations on surfaces exceed those in the air.8

In addition, airflow created by the air filtration systems may disturb allergens that have settled on horizontal surfaces and may actually increase allergen levels in the air.8

The EPA found that impermeable covers on mattresses and pillows were just as effective as air filtration in lowering dust mite levels.8 One meta-analysis showed that air filtration units are ineffective against animal allergens and do not lower pet allergen levels.9 But a study of 30 patients showed that they used less medication when these units were placed in the bedroom and living room.10

Some types of air filters can exacerbate asthma.7,11These air filters generate ozone and are advertised as using “pure air,” “highly activated oxygen,” “super oxide ions,” or “energized oxygen.”7,11“Ion filters” can also create small levels of ozone.8

The cost of air filtration units can be substantial. The prices for these units typically range between $50 and $600, with annual replacement filters costing an additional $20 to $230 each year.7 Because their efficacy is questionable and their annual cost is significant, air filtration systems should be considered as adjuncts to other environmental allergen reduction strategies for severe asthma that is uncontrolled by other means.

Related Content

Interactive Guide

avoiding asthma triggers

Avoiding Asthma Triggers

Share with patients this interactive guide to identifying and reducing triggers to keep asthma symptoms under control.

Does Fido Have To Go?

Pets are an essential part of many homes.12 Pet allergens (dander and fur) worsen asthma symptoms.

A systematic review of pet allergen reduction studies determined that pet washing may reduce allergens short term, but that twice weekly bathing would be necessary to see appreciable results.9 Bathing presents an increased risk of exposure to high levels of allergens.9

It’s unclear whether limiting or restricting exposure to pets and pet hair will lower allergen levels because pet allergens can also be carried on clothes and hands.13 One study found that keeping dogs outdoors decreased dog allergens in the home, but keeping cats outside had no effects.14

Environmental modifications to reduce pet allergens have not proven effective.9 Thus, the only sure way to remove pet allergens is removal of the pet. If removal is unacceptable, recommend HEPA air filters, HEPA filter vacuums or keeping the pet outdoors.


To control mold, it is imperative to keep household humidity levels under 50%. This also limits dust mite populations.15

One study of 62 children showed that large-scale home repairs and alterations in heating and ventilation systems can decrease emergency department visits.16 The mean cost of home repairs was $3,458.16

Dust Mites

The house dust mite is the most common allergen affecting patients with asthma.17A comprehensive review of 49 trials found that no environmental modification aimed at reducing dust mite allergens consistently reduced asthma symptoms.17

Despite this, the NAEPP advocates encasing mattresses and pillows in allergen-impermeable covers and washing sheets and blankets weekly in hot water.2 To kill dust mites, use a temperature higher than 130 degrees Fahrenheit. Alternatively, use detergent and bleach in conjunction with cooler water.2 The NAEPP also recommends vacuuming carpets and upholstered furniture once or twice a week.2 Vacuum when the patient is out of the room or house, because vacuuming can temporarily increase airborne allergen levels.2

Pest Control

Cockroaches, rodents and other pests can be significant allergens in some parts of the country, particularly high-density urban areas.3 One study of 50 children living in public housing found that rat and cockroach pest control resulted in significant reductions in asthma symptoms.18 Another study of 100 children showed that cockroach and rodent extermination with concurrent use of mattress and pillow casings and HEPA air filters resulted in a 50% decrease in allergen levels in the home and decreased daytime asthma symptoms after 1 year.19

Pest control requires eliminating access to food, water and entry into the home (Table 1).3 Families may also want to consider hiring a professional exterminator.

Putting It Into Practice

Developing an effective allergen management plan begins with identifying what exacerbates symptoms. Next, assess efforts the family has already taken, as well as current surroundings (Table 2). Make a list of interventions, and include items in Table 3. A multifaceted approach is needed.


1. Public Education Committee, American Academy of Allergy Asthma & Immunology. Tips to remember: asthma triggers and management. Available at: Accessed Jan. 15, 2009.

2. Control of environmental factors and comorbid conditions that affect asthma. In: National Asthma Education and Prevention Program. Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. Bethesda, Md.: National Heart, Lung, and Blood Institute; 2007:165-212.

3. Public Education Committee, American Academy of Allergy Asthma & Immunology. Tips to remember: indoor allergens. Available at: Accessed Jan. 15, 2009.

4. American Lung Association. Home control of asthma and allergies. Available at: Accessed Jan. 15, 2009.

5. Stapinski H. Let’s talk dirty. American Demographics. 1998;20(11):50-56.

6. Lee YS, Waite LJ. Husbands’ and wives’ time spent on housework: a comparison of measures. J Marriage and Family. 2005;67(2):328-336.

7. Consumer Reports. Air purifiers: filtering the claims. Available at: Accessed Jan. 15, 2009.

8. Environmental Protection Agency. Residential air cleaning devices: a summary of available information. Available at: Accessed Jan. 15, 2009.

9. Kilburn S, et al. Pet allergen control measures for allergic asthma in children and adults. Cochrane Database Syst Rev. 2001;(1)CD002989:1-7.

10. Francis H, et al. Clinical effects of air filters in homes of asthmatic adults sensitized and exposed to pet allergens. Clin Exp Allergy. 2003;33(1):101-105.

11. Environmental Protection Agency. Ozone generators that are sold as air cleaners. Available at: Accessed Jan. 15, 2009.

12. Household pet ownership: 2001. U.S. Pet Ownership and Demographics Sourcebook 2002. Schaumburg, Ill.: American Veterinary Medical Association; 2001.

13. Environmental Protection Agency. About pets and asthma. Available at: Accessed Jan. 15, 2009.

14. Schonberger HJ, et al. Compliance of asthmatic families with a primary prevention programme of asthma and effectiveness of measures to reduce inhalant allergens- a randomized trial. Clin Exp Allergy. 2004;34(7):1024-1031.

15. Environmental Protection Agency. The inside story: a guide to indoor air quality. Available at: Accessed Jan. 15, 2009.

16. Kercsmar CM, et al. Reduction in asthma morbidity in children as a result of home remediation aimed at moisture sources. Environ Health Perspect. 2006;114(10):1574-1580.

17. Gotzsche PC, et al. House dust mite control measures for asthma. Allergy. 2008;63(6):646-659.

18. Levy JI, et al. A community-based participatory research study of multifaceted in-home environmental interventions for pediatric asthmatics in public housing. Soc Sci Med. 2006;63(8):2191-2203.

19. Eggleston PA, et al. Home environmental intervention in inner-city asthma: a randomized controlled clinical trial. Ann Allergy Asthma Immunol. 2005;95(6):518-524.

Kimberly Anderson is a family nurse practitioner at St. Francis Weight Loss Surgery Clinic in Federal Way, Wash. She previously practiced in primary care.

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