Estimating the number of vulnerable people in the United States exposed to residential wood smoke.

Abstract

Vol. 123, No. 2 CorrespondenceOpen AccessEstimating the Number of Vulnerable People in the United States Exposed to Residential Wood Smoke Curtis W. Noonan, Tony J. Ward, and Erin O. Semmens Curtis W. Noonan Search for more papers by this author , Tony J. Ward Search for more papers by this author , and Erin O. Semmens Search for more papers by this author Published:1 February 2015https://doi.org/10.1289/ehp.1409136Cited by:6AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit Rogalsky et al. (2014) recently estimated the number of homes and individuals at risk of adverse health effects from exposure to emissions from residential wood combustion in the United States. We appreciate the importance of this topic, particularly to rural and underserved communities. We also understand the authors’ emphasis on low-income individuals because this population generally has more difficulty accessing health care services and fewer resources available to improve indoor air quality. However, several factors suggest that the indication of 500,000–600,000 low-income persons exposed to household air pollution (HAP) from the burning of solid fuels may be a very conservative estimate, substantially underestimating the public health importance of residential wood combustion.First, the estimate of Rogalsky et al. (2014) was limited by their use of the census-based figure of 2.8 million homes using wood as a primary heating fuel. The U.S. Energy Information Agency (2012) noted that another 8.8 million homes use wood stoves or wood-burning fireplaces as a secondary source of heating. Limited data are available on the frequency of use of wood burning as a secondary heating source and the associated exposure to indoor particulate matter (PM), but the 11.6 million homes with an estimated 2.58 persons per household (U.S. Census Bureau 2012) suggest that closer to 30 million people in the United States live in a home where wood burning is used for heating, rather than the 6.5 million people reported by Rogalsky et al.Second, the authors’ estimate of at-risk persons was limited to those with co-occurrence of in-home wood burning as a primary heating source and households below the Federal Poverty Level (FPL) (i.e., 900,000 people that meet both criteria). However, at-risk individuals, including children and the elderly, also reside in homes that are above the FPL threshold. Third, Rogalsky et al. suggested that 53–65% of wood-burning homes in high-poverty communities may exceed health-based standards, but this estimate is based on few studies, with poverty assessed only at the community level. Finally, the authors focused only on direct indoor fugitive emissions in homes using wood stoves, but exposure risk is not limited to those living in homes with wood-burning appliances. As indicated in several published studies, communities with a high proportion of residential wood-burning households may also have elevated concentrations of ambient wintertime PM (Ward and Lange 2010). Moreover, analyses of infiltration efficiencies suggest that exhausted wood smoke can contribute substantially to indoor PM concentrations in both wood-burning and non–wood-burning homes (Barn et al. 2008), resulting in a higher proportion of homes and their residents experiencing risk from biomass combustion–derived PM. Rogalsky et al. (2014) should be commended for acknowledging these and other limitations in their discussion, and we appreciate the opportunity to provide additional information on these points.Here we offer an alternative framework for estimating the number of people in the United States exposed to high levels of PM associated with wood burning. Approximately 11.6 million homes in the United States use wood as a primary or secondary source of heat. Of these, 4.8 million homes have wood stove appliances (U.S. Energy Information Agency 2012). Because of the uncertain frequency of fireplace use, we have not included homes with fireplaces in our estimate, although they likely are important sources of indoor PM. Rather than limiting our estimate to those homes below the FPL, we define our at-risk population as the susceptible individuals living within these homes (i.e., children and the elderly). With approximately 0.63 children < 18 years of age per household and 0.33 people > 65 years of age per household (U.S. Census Bureau 2012), we estimate that within the United States alone, approximately 4.8 million susceptible individuals live in homes with substantial exposures to wood smoke–derived PM, an order of magnitude greater than the 0.5–0.6 million estimate of Rogalsky et al. (2014). This estimate is conservative because it does not account for infiltration into non–wood stove households experiencing HAP generated from neighboring wood-burning homes, nor does it account for all household residents that are vulnerable due to chronic health conditions.As with any estimates of at-risk populations, there is an important balance to strike between underestimating the risk and artificially inflating the public health importance. We suggest that Rogalsky et al. (2014) erred toward the former. Our estimates are based on a different framework with respect to exposure potential and susceptible populations. Whether the true number of individuals in the United States at risk for adverse health effects from exposure to wood smoke is closer to 0.5 million or 4.8 million, it remains clear that this is an important environmental exposure that disproportionately impacts rural populations.The authors’ research related to residential biomass combustion is supported by the National Institute of Environmental Health Sciences (grants 1R01ES022583, 1R01ES022649, 1R01ES016336).The authors declare they have no actual or potential competing financial interests.ReferencesBarn P, Larson T, Noullett M, Kennedy S, Copes R, Brauer M. 2008. Infiltration of forest fire and residential wood smoke: an evaluation of air cleaner effectiveness.J Expo Sci Environ Epidemiol 18:503-51118059421. Crossref, Medline, Google ScholarRogalsky DK, Mendola P, Metts TA, Martin WJ. 2014. Estimating the number of low-income Americans exposed to household air pollution from burning solid fuels.Environ Health Perspect 122:806-810; doi:10.1289/ehp.130670924833615. Link, Google ScholarU.S. Census Bureau.2012. Households and Families: 2010 Census Briefs.Available: http://www.census.gov/prod/cen2010/briefs/c2010br-14.pdf [accessed 22 August 2014]. Google ScholarU.S. Energy Information Agency.2012. Residential Energy Consumption Survey. 2009 RECS Survey Data.Available: http://www.eia.gov/consumption/residential/data/2009/ [accessed 15 January 2015]. Google ScholarWard T, Lange T. 2010. The impact of wood smoke on ambient PM2.5 in northern Rocky Mountain valley communities.Environ Pollut 158(3):723-72919897293. Crossref, Medline, Google ScholarFiguresReferencesRelatedDetailsCited ByWhite J, Wyss A, Hoang T, Lee M, Richards M, Parks C, Beane-Freeman L, Hankinson J, Umbach D and London S (2022) Residential Wood Burning and Pulmonary Function in the Agricultural Lung Health Study, Environmental Health Perspectives, 130:8, Online publication date: 1-Aug-2022. Montrose L, Goodrich J and Dolinoy D (2017) Toxicoepigenetics and Effects on Life Course Disease Susceptibility Translational Toxicology and Therapeutics: Windows of Developmental Susceptibility in Reproduction and Cancer, 10.1002/9781119023647.ch13, (439-472) Rokoff L, Koutrakis P, Garshick E, Karagas M, Oken E, Gold D and Fleisch A (2017) Wood Stove Pollution in the Developed World: A Case to Raise Awareness Among Pediatricians, Current Problems in Pediatric and Adolescent Health Care, 10.1016/j.cppeds.2017.04.001, 47:6, (123-141), Online publication date: 1-Jun-2017. McNamara M, Thornburg J, Semmens E, Ward T and Noonan C (2017) Reducing indoor air pollutants with air filtration units in wood stove homes, Science of The Total Environment, 10.1016/j.scitotenv.2017.03.111, 592, (488-494), Online publication date: 1-Aug-2017. Noonan C, Semmens E, Smith P, Harrar S, Montrose L, Weiler E, McNamara M and Ward T (2017) Randomized Trial of Interventions to Improve Childhood Asthma in Homes with Wood-burning Stoves, Environmental Health Perspectives, 125:9, Online publication date: 22-Sep-2017. Kotchenruther R (2016) Source apportionment of PM 2.5 at multiple Northwest U.S. sites: Assessing regional winter wood smoke impacts from residential wood combustion, Atmospheric Environment, 10.1016/j.atmosenv.2016.07.048, 142, (210-219), Online publication date: 1-Oct-2016. Vol. 123, No. 2 February 2015Metrics About Article Metrics Publication History Originally published1 February 2015Published in print1 February 2015 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.