Outdoor air pollution in close proximity to a continuous point source |
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| Authors: | Neil E. Klepeis Etienne B. Gabel Wayne R. Ott Paul Switzer |
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| Affiliation: | 1. Child Neuropsychiatry Unit, Department of Neuroscience, University-Hospital of Parma, Parma, Italy;2. Department of Life and Reproduction Sciences, University of Verona, Verona, Italy;3. Department of Neuroradiology, University-Hospital of Parma, Parma, Italy;1. Pneumology Department, Hospital Universitari Vall d’Hebron; Vall d’Hebron Institut de Recerca (VHIR), Vall d’Hebron Barcelona Hospital Campus, Barcelona, Spain;2. CIBER de Enfermedades Respiratorias (CIBERES), Spain;3. 2nd Department of Respiratory Medicine, Institute of Tuberculosis and Lung Diseases, Warsaw, Poland;4. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Seoul St. Mary''s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea;5. Department of Respiratory Medicine, Royal College of Surgeons, Dublin, Ireland;6. Optimum Patient Care, Cambridge, UK;7. Department of Respiratory and Critical Care Medicine, Singapore General Hospital, Singapore;8. Duke-National University of Singapore Medical School, Singapore;9. Department of Respiratory Medicine, Bispebjerg Hospital, Copenhagen, Denmark;10. Respiratory Department, Hospital de Alta Resolución de Loja, Spain;11. Department of Respiratory Medicine, Mater Dei Hospital, Malta;12. Public Health, Mental, Maternal and Child Health Nursing Department, Faculty of Medicine and Health Sciences, University of Barcelona, Spain;13. Department of Respiratory Medicine, Hospital Comarcal de Laredo, Cantabria, Spain;14. Respiratory and Critical Care Medicine, Changi General Hospital, Singapore;15. Primary Health-care Center Son Pisà, IB-Salut, Palma, Baleares, Spain;p. Pneumology Department, Hospital Arnau de Vilanova, Valencia, Spain;q. Centre of Academic Primary Care, University of Aberdeen, UK;r. Observational and Pragmatic Research Institute, Singapore;11. Hospital Universitari Vall d’Hebron, Barcelona, Spain;12. Hospital de Alta Resolución de Loja, Spain;13. Hospital Comarcal de Laredo, Cantabria, Spain;14. Primary Health-care Center Son Pisà, IB-Salut, Palma de Mallorca, Spain;15. Institute of Tuberculosis and Lung Diseases, Warsaw, Poland;16. St Mary''s Hospital, Seoul, Korea;17. Singapore General Hospital, Singapore;18. Changi General Hospital, Singapore;19. Optimum Patient Care, Cambridge, UK;110. Mater Dei Hospital, Malta;111. Royal College of Surgeons, Dublin, Ireland;1. United States Environmental Protection Agency (U.S. EPA), Office of Research and Development, RTP, NC 27711, United States;2. Student Services Contractor at U.S. EPA, RTP, NC, United States;3. Lockheed-Martin Information Technology, RTP, NC 27711, United States;4. North Carolina State University, 2200 Hillsborough St., Raleigh, NC 27695, United States;5. Oak Ridge Institute for Science and Education Fellow, United States;6. University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, United States;7. Biosystems and Agricultural Engineering, Michigan State University, E. Lansing, MI 48824, United States |
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| Abstract: | Data are lacking on human exposure to air pollutants occurring in ground-level outdoor environments within a few meters of point sources. To better understand outdoor exposure to tobacco smoke from cigarettes or cigars, and exposure to other types of outdoor point sources, we performed more than 100 controlled outdoor monitoring experiments on a backyard residential patio in which we released pure carbon monoxide (CO) as a tracer gas for continuous time periods lasting 0.5–2 h. The CO was emitted from a single outlet at a fixed per-experiment rate of 120–400 cc min?1 (～140–450 mg min?1). We measured CO concentrations every 15 s at up to 36 points around the source along orthogonal axes. The CO sensors were positioned at standing or sitting breathing heights of 2–5 ft (up to 1.5 ft above and below the source) and at horizontal distances of 0.25–2 m. We simultaneously measured real-time air speed, wind direction, relative humidity, and temperature at single points on the patio. The ground-level air speeds on the patio were similar to those we measured during a survey of 26 outdoor patio locations in 5 nearby towns. The CO data exhibited a well-defined proximity effect similar to the indoor proximity effect reported in the literature. Average concentrations were approximately inversely proportional to distance. Average CO levels were approximately proportional to source strength, supporting generalization of our results to different source strengths. For example, we predict a cigarette smoker would cause average fine particle levels of approximately 70–110 μg m?3 at horizontal distances of 0.25–0.5 m. We also found that average CO concentrations rose significantly as average air speed decreased. We fit a multiplicative regression model to the empirical data that predicts outdoor concentrations as a function of source emission rate, source–receptor distance, air speed and wind direction. The model described the data reasonably well, accounting for ～50% of the log-CO variability in 5-min CO concentrations. |
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