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Guest Editorials / Ann Allergy Asthma Immunol 114 (2015) 159e161
[4] Hohlfeld JM, Holland-Letz T, Larbig M, et al. Diagnostic value of outcome measures following allergen exposure in an environmental challenge chamber compared with natural conditions. Clin Exp Allergy. 2010;40:998e1006. [5] Jacobs RL, Harper N, He W, et al. Responses to ragweed pollen in a pollen challenge chamber versus seasonal exposure identify allergic rhinoconjunctivitis endotypes. J Allergy Clin Immunol. 2012;130:122e127. e8. [6] Jacobs RL, Harper N, He W, et al. Effect of confounding cofactors on responses to pollens during natural season versus pollen challenge chamber exposure. J Allergy Clin Immunol. 2014;133:1340e1346. e1ee7. [7] Ramirez DA, Andrews CP, Rather CG, Jacobs RL. Responsiveness to timothy grass pollen in individuals without known natural exposure in an allergen challenge chamber. Ann Allergy Asthma Immunol. 2015;114:226-232.
[8] Davies JM, Li H, Green M, Towers M, Upham JW. Subtropical grass pollen allergens are important for allergic respiratory diseases in subtropical regions. Clin Transl Allergy. 2012;2:4. [9] Food and Drug Administration. Center for Biologics Evaluation and Research, Allergenic Products Advisory Committee. Committee meeting; May 12, 2011 [transcript]. Washington, DC: Capital Reporting Company; 2011. http://www. fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/Blood VaccinesandOtherBiologics/AllergenicProductsAdvisoryCommittee/UCM258587. pdf. Published 2011. [10] Devillier P, Le Gall M, Horak F. The allergen challenge chamber: a valuable tool for optimizing the clinical development of pollen immunotherapy. Allergy. 2011;66:163e169.
A new method for air sampling with real-world results Atopic individuals who manifest clinical symptoms of rhinitis and asthma are often found to have sensitivities to allergens found in the indoor home environment. Inhalable allergens are found in the settled dust in homes and, when disturbed, reach the “breathing zone” to trigger allergic responses. Targeted avoidance measures to reduce allergens have been found to be disease modifying.1 Recently, the Joint Task Force on Practice Parameters published a series of parameters focused on assessment and exposure reduction to major indoor allergens: furry animals, rodents, cockroach, dust mite, and fungi (in review).2e5 The parameters recommend assessment of the levels of indoor allergens as a tool in identifying the degree of exposure and determining the success (or failure) of environmental interventions. Most airborne allergens are glycoproteins with molecular weights between 6 and 100 kD. They are delivered to the airways on carrier particles in the forms of pollen grains, fungi spores or mycelium fragments, or mite fecal particles or by adherence to particulate matter.6 With the exception of carrier particles larger than 10 mm (pollen grains, mold spores, and dust mites), most remain airborne for various lengths of time before precipitating into settled dust. Outside research or occupational settings, the most practical and costeffective way of measuring indoor allergens has been by vacuuming surfaces to obtain settled dust samples, which are then analyzed in the laboratory for allergen content using either monoclonal or polyclonal antibody assays. Studies have found there may be poor correlation between levels of allergens found in settled dust vs airborne sampling.7 The recent practice parameter on furry animals recommends that the measurement of cat allergens in settled dust not be used as a surrogate for airborne exposure.2 The European Academy of Allergy and Clinical Immunology position paper Monitoring of Occupational and Environmental Aeroallergens states that in the indoor (domestic) environment, the allergen content of settled or reservoir dust is typically used to provide estimates of exposure levels but recommends that, ideally, allergen exposure assessment should be based on (active) measurement of airborne concentrations.6 In an article in this issue of the Annals, Barnes et al8 report allergen assays (Fel d 1, Can f 1, Mus m 1, Der f 1, Der p 1, and Bla g 2) and fungal cultures obtained from dust collected by vacuuming the surfaces of high-efficiency (minimum efficiency rating value [MERV] of 12) heating, ventilating, and air conditioning (HVAC) furnace filters from the homes of families participating in the Kansas City Safe and Healthy Homes Project. The collection period spanned both the air conditioning and heating seasons. The study found that all 5 common aeroallergens could be measured on the filters, along with evidence of airborne fungi in the homes that deposit over time on the furnace filters. Because the study was not standardized for the length of time the filters remained in place, one cannot speculate on the differences in levels of the various aeroallergens measured, although they reach the filter surface, are trapped, and can be assayed from the filter dust. Disclosures: Dr. Sublett is the founder and minority owner of AllergyZone LLC.
Air filtration, either high-efficiency whole-house filtration or portable room air cleaners equipped with high-efficiency particulate air filters, has been reviewed and is generally believed to offer benefit as a component of the overall avoidance measures taken for tertiary prevention of allergic disease.9 More than 97 million homes (>75%) in the United States have HVAC units.10 The use of disposable 1-in HVAC high-efficiency (MERV 11) furnace filters, therefore, is an attractive option because of low cost (approximately $60 per year) and potential health benefits. This is the first real-world study to measure allergens deposited on HVAC (furnace) filters in homes. This study confirms that significant amounts of airborne allergens are capable of reaching the furnace filters, which are located on the cold air return side of the system. Prior studies of whole-house filtration are modeling studies to determine particulate removal representative of particulates in the same size range as those that carry allergens.10 Another significant finding in the article is that viable mold spores were present on the filters, indicating significant airborne fungi in the homes capable of colonization for mold growth. The high-efficiency filters used in the study are capable of containing the spores in the dust on the upstream surface, even when fully loaded, whereas porous loosely woven filters may become a reservoir for downstream release and contamination of the entire HVAC duct work system as the filter fails. Aspergillus fumigatus, a mold associated with damp homes, was found to be as high as 100,000 ng/g of dust in one sample, with a mean level of more than 34,000 ng/g. Cladosporium herbarum was found at even higher mean levels of greater than 42,000 ng/g of dust. The length of time the filters were in place may have contributed to the load, but this is no different than vacuuming a carpeted floor to assess allergen load in that the amount of contamination over time would affect the measured levels. Both Fel d 1 and Can f 1 levels were found to be significantly high in homes reported to have no inside animals. This finding has been noted previously, but the degree of deposition found on the filters confirms not only that animal allergen exposure is ubiquitous but also that high levels of airborne allergens may be present in homes where furry pets do not live. The results of this study raise several questions that need to be answered by further research: Because of the variability of filter media and construction, is there consistency between similarly rated MERV filters if used in sampling? Could this method of dust collection of airborne allergens be standardized by establishing a standard period that the filter would be left in place (the recommended change interval of 3 months) before sampling to give comparative results between homes? If a sampling protocol is established, could this be used as an inexpensive method for the treating allergists and homeowners to measure the success of environmental interventions over time in reducing allergen exposure?
Guest Editorials / Ann Allergy Asthma Immunol 114 (2015) 159e161
James L. Sublett, MD Pediatric Allergy & Immunology University of Louisville School of Medicine Louisville, Kentucky [email protected]
References [1] Morgan WJ, Crain EF, Gruchalla RS, et al. Results of a home-based environmental intervention among urban children with asthma. N Engl J Med. 2004; 351:1068e1080. [2] Portnoy J, Kennedy K, Sublett J. Environmental assessment and exposure control: a practice parameter - furry animals. Ann Allergy Asthma Immunol. 2012;108:223.e1e223.e15. [3] Phipatanakul W, Matsui E, Portnoy J, et al. Environmental assessment and exposure reduction of rodents: a practice parameter. Ann Allergy Asthma Immunol. 2012;109:375e387.
161
[4] Portnoy J, Chew GL, Phipatanakul W, et al. Joint Task Force on Practice Parameters. Environmental assessment and exposure reduction of cockroaches: a practice parameter. J Allergy Clin Immunol. 2013;132:802e808.e1e25. [5] Portnoy J, Miller JD, Williams PB, et al. Environmental assessment and exposure control of dust mites: a practice parameter. Ann Allergy Asthma Immunol. 2013;111:465e507. [6] Raulf M, Buters J, Chapman M, et al. Monitoring of occupational and environmental aeroallergens: EAACI Position Paper. Allergy. 2014;69: 1280e1299. [7] Peterson EL, Ownby DR, Kallenbach L, Johnson CC. Evaluation of air and dust sampling schemes for Fel d 1, Der f 1, and Der p 1 allergens in homes in the Detroit area. J Allergy Clin Immunol. 1999;104(2, pt 1):348e355. [8] Barnes CS, Allenbrand R, Mohammed M, et al. Measurement of aeroallergens from furnace filters. Ann Allergy Asthma Immunol. 2015;114:221-225. [9] Sublett JL, Seltzer J, Burkhead R, Williams PB, Wedner HJ, Phipatanakul W. Air filters and air cleaners: rostrum by the American Academy of Allergy, Asthma & Immunology Indoor Allergen Committee. J Allergy Clin Immunol. 2010;125:32e38. [10] Brown KW, Minegishi T, Allen JG, McCarthy JF, Spengler JD, MacIntosh DL. Reducing patients’ exposures to asthma and allergy triggers in their homes: an evaluation of effectiveness of grades of forced air ventilation filters. J Asthma. 2014;51:585e594.
Guest Editorials / Ann Allergy Asthma Immunol 114 (2015) 159e161
[4] Hohlfeld JM, Holland-Letz T, Larbig M, et al. Diagnostic value of outcome measures following allergen exposure in an environmental challenge chamber compared with natural conditions. Clin Exp Allergy. 2010;40:998e1006. [5] Jacobs RL, Harper N, He W, et al. Responses to ragweed pollen in a pollen challenge chamber versus seasonal exposure identify allergic rhinoconjunctivitis endotypes. J Allergy Clin Immunol. 2012;130:122e127. e8. [6] Jacobs RL, Harper N, He W, et al. Effect of confounding cofactors on responses to pollens during natural season versus pollen challenge chamber exposure. J Allergy Clin Immunol. 2014;133:1340e1346. e1ee7. [7] Ramirez DA, Andrews CP, Rather CG, Jacobs RL. Responsiveness to timothy grass pollen in individuals without known natural exposure in an allergen challenge chamber. Ann Allergy Asthma Immunol. 2015;114:226-232.
[8] Davies JM, Li H, Green M, Towers M, Upham JW. Subtropical grass pollen allergens are important for allergic respiratory diseases in subtropical regions. Clin Transl Allergy. 2012;2:4. [9] Food and Drug Administration. Center for Biologics Evaluation and Research, Allergenic Products Advisory Committee. Committee meeting; May 12, 2011 [transcript]. Washington, DC: Capital Reporting Company; 2011. http://www. fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/Blood VaccinesandOtherBiologics/AllergenicProductsAdvisoryCommittee/UCM258587. pdf. Published 2011. [10] Devillier P, Le Gall M, Horak F. The allergen challenge chamber: a valuable tool for optimizing the clinical development of pollen immunotherapy. Allergy. 2011;66:163e169.
A new method for air sampling with real-world results Atopic individuals who manifest clinical symptoms of rhinitis and asthma are often found to have sensitivities to allergens found in the indoor home environment. Inhalable allergens are found in the settled dust in homes and, when disturbed, reach the “breathing zone” to trigger allergic responses. Targeted avoidance measures to reduce allergens have been found to be disease modifying.1 Recently, the Joint Task Force on Practice Parameters published a series of parameters focused on assessment and exposure reduction to major indoor allergens: furry animals, rodents, cockroach, dust mite, and fungi (in review).2e5 The parameters recommend assessment of the levels of indoor allergens as a tool in identifying the degree of exposure and determining the success (or failure) of environmental interventions. Most airborne allergens are glycoproteins with molecular weights between 6 and 100 kD. They are delivered to the airways on carrier particles in the forms of pollen grains, fungi spores or mycelium fragments, or mite fecal particles or by adherence to particulate matter.6 With the exception of carrier particles larger than 10 mm (pollen grains, mold spores, and dust mites), most remain airborne for various lengths of time before precipitating into settled dust. Outside research or occupational settings, the most practical and costeffective way of measuring indoor allergens has been by vacuuming surfaces to obtain settled dust samples, which are then analyzed in the laboratory for allergen content using either monoclonal or polyclonal antibody assays. Studies have found there may be poor correlation between levels of allergens found in settled dust vs airborne sampling.7 The recent practice parameter on furry animals recommends that the measurement of cat allergens in settled dust not be used as a surrogate for airborne exposure.2 The European Academy of Allergy and Clinical Immunology position paper Monitoring of Occupational and Environmental Aeroallergens states that in the indoor (domestic) environment, the allergen content of settled or reservoir dust is typically used to provide estimates of exposure levels but recommends that, ideally, allergen exposure assessment should be based on (active) measurement of airborne concentrations.6 In an article in this issue of the Annals, Barnes et al8 report allergen assays (Fel d 1, Can f 1, Mus m 1, Der f 1, Der p 1, and Bla g 2) and fungal cultures obtained from dust collected by vacuuming the surfaces of high-efficiency (minimum efficiency rating value [MERV] of 12) heating, ventilating, and air conditioning (HVAC) furnace filters from the homes of families participating in the Kansas City Safe and Healthy Homes Project. The collection period spanned both the air conditioning and heating seasons. The study found that all 5 common aeroallergens could be measured on the filters, along with evidence of airborne fungi in the homes that deposit over time on the furnace filters. Because the study was not standardized for the length of time the filters remained in place, one cannot speculate on the differences in levels of the various aeroallergens measured, although they reach the filter surface, are trapped, and can be assayed from the filter dust. Disclosures: Dr. Sublett is the founder and minority owner of AllergyZone LLC.
Air filtration, either high-efficiency whole-house filtration or portable room air cleaners equipped with high-efficiency particulate air filters, has been reviewed and is generally believed to offer benefit as a component of the overall avoidance measures taken for tertiary prevention of allergic disease.9 More than 97 million homes (>75%) in the United States have HVAC units.10 The use of disposable 1-in HVAC high-efficiency (MERV 11) furnace filters, therefore, is an attractive option because of low cost (approximately $60 per year) and potential health benefits. This is the first real-world study to measure allergens deposited on HVAC (furnace) filters in homes. This study confirms that significant amounts of airborne allergens are capable of reaching the furnace filters, which are located on the cold air return side of the system. Prior studies of whole-house filtration are modeling studies to determine particulate removal representative of particulates in the same size range as those that carry allergens.10 Another significant finding in the article is that viable mold spores were present on the filters, indicating significant airborne fungi in the homes capable of colonization for mold growth. The high-efficiency filters used in the study are capable of containing the spores in the dust on the upstream surface, even when fully loaded, whereas porous loosely woven filters may become a reservoir for downstream release and contamination of the entire HVAC duct work system as the filter fails. Aspergillus fumigatus, a mold associated with damp homes, was found to be as high as 100,000 ng/g of dust in one sample, with a mean level of more than 34,000 ng/g. Cladosporium herbarum was found at even higher mean levels of greater than 42,000 ng/g of dust. The length of time the filters were in place may have contributed to the load, but this is no different than vacuuming a carpeted floor to assess allergen load in that the amount of contamination over time would affect the measured levels. Both Fel d 1 and Can f 1 levels were found to be significantly high in homes reported to have no inside animals. This finding has been noted previously, but the degree of deposition found on the filters confirms not only that animal allergen exposure is ubiquitous but also that high levels of airborne allergens may be present in homes where furry pets do not live. The results of this study raise several questions that need to be answered by further research: Because of the variability of filter media and construction, is there consistency between similarly rated MERV filters if used in sampling? Could this method of dust collection of airborne allergens be standardized by establishing a standard period that the filter would be left in place (the recommended change interval of 3 months) before sampling to give comparative results between homes? If a sampling protocol is established, could this be used as an inexpensive method for the treating allergists and homeowners to measure the success of environmental interventions over time in reducing allergen exposure?
Guest Editorials / Ann Allergy Asthma Immunol 114 (2015) 159e161
James L. Sublett, MD Pediatric Allergy & Immunology University of Louisville School of Medicine Louisville, Kentucky [email protected]
References [1] Morgan WJ, Crain EF, Gruchalla RS, et al. Results of a home-based environmental intervention among urban children with asthma. N Engl J Med. 2004; 351:1068e1080. [2] Portnoy J, Kennedy K, Sublett J. Environmental assessment and exposure control: a practice parameter - furry animals. Ann Allergy Asthma Immunol. 2012;108:223.e1e223.e15. [3] Phipatanakul W, Matsui E, Portnoy J, et al. Environmental assessment and exposure reduction of rodents: a practice parameter. Ann Allergy Asthma Immunol. 2012;109:375e387.
161
[4] Portnoy J, Chew GL, Phipatanakul W, et al. Joint Task Force on Practice Parameters. Environmental assessment and exposure reduction of cockroaches: a practice parameter. J Allergy Clin Immunol. 2013;132:802e808.e1e25. [5] Portnoy J, Miller JD, Williams PB, et al. Environmental assessment and exposure control of dust mites: a practice parameter. Ann Allergy Asthma Immunol. 2013;111:465e507. [6] Raulf M, Buters J, Chapman M, et al. Monitoring of occupational and environmental aeroallergens: EAACI Position Paper. Allergy. 2014;69: 1280e1299. [7] Peterson EL, Ownby DR, Kallenbach L, Johnson CC. Evaluation of air and dust sampling schemes for Fel d 1, Der f 1, and Der p 1 allergens in homes in the Detroit area. J Allergy Clin Immunol. 1999;104(2, pt 1):348e355. [8] Barnes CS, Allenbrand R, Mohammed M, et al. Measurement of aeroallergens from furnace filters. Ann Allergy Asthma Immunol. 2015;114:221-225. [9] Sublett JL, Seltzer J, Burkhead R, Williams PB, Wedner HJ, Phipatanakul W. Air filters and air cleaners: rostrum by the American Academy of Allergy, Asthma & Immunology Indoor Allergen Committee. J Allergy Clin Immunol. 2010;125:32e38. [10] Brown KW, Minegishi T, Allen JG, McCarthy JF, Spengler JD, MacIntosh DL. Reducing patients’ exposures to asthma and allergy triggers in their homes: an evaluation of effectiveness of grades of forced air ventilation filters. J Asthma. 2014;51:585e594.
