title: Reducing patients' exposures to asthma and allergy triggers in their homes: an evaluation of effectiveness of grades of forced air ventilation filters.
abstract: OBJECTIVE
  Many interventions to reduce allergen levels in the home are recommended to asthma and allergy patients. One that is readily available and can be highly effective is the use of high performing filters in forced air ventilation systems.
  
  
  METHODS
  We conducted a modeling analysis of the effectiveness of filter-based interventions in the home to reduce airborne asthma and allergy triggers. This work used "each pass removal efficiency" applied to health-relevant size fractions of particles to assess filter performance. We assessed effectiveness for key allergy and asthma triggers based on applicable particle sizes for cat allergen, indoor and outdoor sources of particles <2.5 µm in diameter (PM2.5), and airborne influenza and rhinovirus.
  
  
  RESULTS
  Our analysis finds that higher performing filters can have significant impacts on indoor particle pollutant levels. Filters with removal efficiencies of >70% for cat dander particles, fine particulate matter (PM2.5) and respiratory virus can lower concentrations of those asthma triggers and allergens in indoor air of the home by >50%. Very high removal efficiency filters, such as those rated a 16 on the nationally recognized Minimum Efficiency Removal Value (MERV) rating system, tend to be only marginally more effective than MERV12 or 13 rated filters.
  
  
  CONCLUSIONS
  The results of this analysis indicate that use of a MERV12 or higher performing air filter in home ventilation systems can effectively reduce indoor levels of these common asthma and allergy triggers. These reductions in airborne allergens in turn may help reduce allergy and asthma symptoms, especially if employed in conjunction with other environmental management measures recommended for allergy and asthma patients.
authors.affiliation: Environmental Health & Engineering, Inc. , Needham, MA , USA and.
authors.forename: Kathleen Ward
authors.initials: KW
authors.lastname: Brown
authors.forename: Taeko
authors.initials: T
authors.lastname: Minegishi
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Allen
authors.forename: John F
authors.initials: JF
authors.lastname: McCarthy
authors.forename: John D
authors.initials: JD
authors.lastname: Spengler
authors.forename: David L
authors.initials: DL
authors.lastname: MacIntosh
mesh_terms: D061808:Air Filters; D016902:Air Pollution, Indoor / Q000032:analysis / Q000517:prevention & control*; D000485:Allergens / Q000032:analysis*; D000818:Animals; D001249:Asthma / Q000517:prevention & control*; D002415:Cats; D004781:Environmental Exposure / Q000032:analysis / Q000517:prevention & control*; D004784:Environmental Monitoring; D006801:Humans; D052638:Particulate Matter / Q000032:analysis; D014691:Ventilation; D014780:Viruses
chemical_list: D000485:Allergens; D052638:Particulate Matter
keywords: Asthma and allergy triggers; PM2.5; filtration; indoor air; particulate