Do air purifiers resolve asthma and its triggers?

Air Purifiers Do Not Resolve Asthma But May Help Reduce Some Triggers in Specific Circumstances

Air purifiers alone are not effective for resolving asthma, and there is insufficient evidence to recommend them as a single-component intervention for asthma management. 1 However, they may provide modest benefits in reducing certain asthma triggers for specific patient populations when used as part of a comprehensive allergen mitigation strategy.

Evidence on Air Purifiers for Asthma Management

Single-Component Intervention

• Studies examining air purifiers as a standalone intervention show limited effectiveness for critical asthma outcomes:
  • No decrease in exacerbations
  • No improvement in quality of life
  • Mixed results for asthma control (low certainty evidence)
  • Mixed results for asthma symptoms (low certainty evidence) 1

As Part of Multicomponent Interventions

• When air purifiers (particularly those with HEPA filters) are used as part of multicomponent allergen mitigation strategies:
  • Some studies showed decreased severity or number of reported asthma symptoms in children, but not in mixed populations (low certainty evidence)
  • No significant reduction in exacerbations or improvement in quality of life (high certainty evidence) 1

Specific Allergen Considerations

Pet Allergens

• For patients with specific pet allergies:
  • Some evidence suggests air cleaners can capture airborne cat and dog allergens 2
  • A 2020 study demonstrated that air cleaners significantly prevented early and late asthmatic responses among cat-allergic asthmatics during controlled cat allergen exposure 3
  • However, observational studies have not found that removing a pet from the home improves asthma control 1

House Dust Mites

• Air purifiers may help reduce airborne house dust mite allergens 4
• However, dust mite mitigation using impermeable mattress and pillow covers as a single intervention showed no benefit for critical asthma outcomes 1

Pollen

• Individual wearable air purifiers may provide some protection against airborne pollen for allergic rhinoconjunctivitis patients 5

Important Considerations for Air Purifier Use

Potential Risks

• Ozone-generating "air purifiers" should be avoided as they can produce harmful ozone levels 6
• Air ionizers cannot be recommended as there is no evidence of benefit and some suggestion of adverse effects, including increased nocturnal cough 1
• Air purifiers that add humidity should be avoided due to increased risk of mold growth and dust mite proliferation 6

Technical Specifications

• HEPA air purifiers with minimum removal efficiency of 99.97% of particles ≥0.3 μm are recommended if using air purifiers 6
• Filters with removal efficiencies of >70% for allergens and fine particulate matter can lower concentrations of those triggers in indoor air by >50% 7
• MERV12 or higher performing air filters in home ventilation systems can effectively reduce indoor levels of common asthma and allergy triggers 7

Recommendations for Clinical Practice

1. Do not recommend air purifiers as a primary treatment for asthma

   • Scheduled, daily inhaled corticosteroid treatment remains the cornerstone of asthma management 1

2. Consider air purifiers only for patients with:

   • Confirmed specific allergen sensitivities through testing
   • Documented exposure to those allergens
   • Symptoms related to those exposures 1

3. If recommending air purifiers:

   • Use only as part of a multicomponent allergen mitigation strategy
   • Select HEPA filtration systems rather than ionizers
   • Ensure proper placement in rooms where patients spend most time, especially bedrooms
   • Maintain regular inspection and cleaning of filters 6

4. Focus on comprehensive allergen management:

   • Integrated pest management for cockroaches/rodents when relevant
   • HEPA vacuum cleaners
   • Mold mitigation when applicable
   • Impermeable pillow/mattress covers (only as part of multicomponent strategy) 1

Air purifiers represent just one potential tool in allergen management and should not be viewed as a solution for asthma itself. The evidence suggests modest benefits in specific circumstances, but they should be considered as an adjunct to proper medical management with controller medications.