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. 2003 Jul;111(9):1170–1174. doi: 10.1289/ehp.5883

On the relationship between time-series studies, dynamic population studies, and estimating loss of life due to short-term exposure to environmental risks.

Richard T Burnett 1, Anup Dewanji 1, Francesca Dominici 1, Mark S Goldberg 1, Aaron Cohen 1, Daniel Krewski 1
PMCID: PMC1241570  PMID: 12842769

Abstract

There is a growing concern that short-term exposure to combustion-related air pollution is associated with increased risk of death. This finding is based largely on time-series studies that estimate associations between daily variations in ambient air pollution concentrations and in the number of nonaccidental deaths within a community. Because these results are not based on cohort or dynamic population designs, where individuals are followed in time, it has been suggested that estimates of effect from these time-series studies cannot be used to determine the amount of life lost because of short-term exposures. We show that results from time-series studies are equivalent to estimates obtained from a dynamic population when each individual's survival experience can be summarized as the daily number of deaths. This occurs when the following conditions are satisfied: a) the environmental covariates vary in time and not between individuals; b) on any given day, the probability of death is small; c) on any given day and after adjusting for known risk factors for mortality such age, sex, smoking habits, and environmental exposures, each subject of the at-risk population has the same probability of death; d) environmental covariates have a common effect on mortality of all members of at-risk population; and e) the averages of individual risk factors, such as smoking habits, over the at-risk population vary smoothly with time. Under these conditions, the association between temporal variation in the environmental covariates and the survival experience of members of the dynamic population can be estimated by regressing the daily number of deaths on the daily value of the environmental covariates, as is done in time-series mortality studies. Issues in extrapolating risk estimates based on time-series studies in one population to estimate the amount of life lost in another population are also discussed.

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Selected References

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  1. Abbey D. E., Nishino N., McDonnell W. F., Burchette R. J., Knutsen S. F., Lawrence Beeson W., Yang J. X. Long-term inhalable particles and other air pollutants related to mortality in nonsmokers. Am J Respir Crit Care Med. 1999 Feb;159(2):373–382. doi: 10.1164/ajrccm.159.2.9806020. [DOI] [PubMed] [Google Scholar]
  2. Brunekreef B. Air pollution and life expectancy: is there a relation? Occup Environ Med. 1997 Nov;54(11):781–784. doi: 10.1136/oem.54.11.781. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Burnett R., Ma R., Jerrett M., Goldberg M. S., Cakmak S., Pope C. A., 3rd, Krewski D. The spatial association between community air pollution and mortality: a new method of analyzing correlated geographic cohort data. Environ Health Perspect. 2001 Jun;109 (Suppl 3):375–380. doi: 10.1289/ehp.01109s3375. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Dockery D. W., Pope C. A., 3rd, Xu X., Spengler J. D., Ware J. H., Fay M. E., Ferris B. G., Jr, Speizer F. E. An association between air pollution and mortality in six U.S. cities. N Engl J Med. 1993 Dec 9;329(24):1753–1759. doi: 10.1056/NEJM199312093292401. [DOI] [PubMed] [Google Scholar]
  5. Goldberg M. S., Burnett R. T., Bailar J. C., 3rd, Tamblyn R., Ernst P., Flegel K., Brook J., Bonvalot Y., Singh R., Valois M. F. Identification of persons with cardiorespiratory conditions who are at risk of dying from the acute effects of ambient air particles. Environ Health Perspect. 2001 Aug;109 (Suppl 4):487–494. doi: 10.1289/ehp.01109s4487. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Katsouyanni K., Touloumi G., Samoli E., Gryparis A., Le Tertre A., Monopolis Y., Rossi G., Zmirou D., Ballester F., Boumghar A. Confounding and effect modification in the short-term effects of ambient particles on total mortality: results from 29 European cities within the APHEA2 project. Epidemiology. 2001 Sep;12(5):521–531. doi: 10.1097/00001648-200109000-00011. [DOI] [PubMed] [Google Scholar]
  7. Katsouyanni K., Touloumi G., Spix C., Schwartz J., Balducci F., Medina S., Rossi G., Wojtyniak B., Sunyer J., Bacharova L. Short-term effects of ambient sulphur dioxide and particulate matter on mortality in 12 European cities: results from time series data from the APHEA project. Air Pollution and Health: a European Approach. BMJ. 1997 Jun 7;314(7095):1658–1663. doi: 10.1136/bmj.314.7095.1658. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Künzli N., Medina S., Kaiser R., Quénel P., Horak F., Jr, Studnicka M. Assessment of deaths attributable to air pollution: should we use risk estimates based on time series or on cohort studies? Am J Epidemiol. 2001 Jun 1;153(11):1050–1055. doi: 10.1093/aje/153.11.1050. [DOI] [PubMed] [Google Scholar]
  9. Lee J. T., Schwartz J. Reanalysis of the effects of air pollution on daily mortality in Seoul, Korea: A case-crossover design. Environ Health Perspect. 1999 Aug;107(8):633–636. doi: 10.1289/ehp.99107633. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. McMichael A. J., Anderson H. R., Brunekreef B., Cohen A. J. Inappropriate use of daily mortality analyses to estimate longer-term mortality effects of air pollution. Int J Epidemiol. 1998 Jun;27(3):450–453. doi: 10.1093/ije/27.3.450. [DOI] [PubMed] [Google Scholar]
  11. Moolgavkar S. H. Air pollution and daily mortality in three U.S. counties. Environ Health Perspect. 2000 Aug;108(8):777–784. doi: 10.1289/ehp.00108777. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Pope C. A., 3rd, Thun M. J., Namboodiri M. M., Dockery D. W., Evans J. S., Speizer F. E., Heath C. W., Jr Particulate air pollution as a predictor of mortality in a prospective study of U.S. adults. Am J Respir Crit Care Med. 1995 Mar;151(3 Pt 1):669–674. doi: 10.1164/ajrccm/151.3_Pt_1.669. [DOI] [PubMed] [Google Scholar]
  13. Pope C. Arden, 3rd, Burnett Richard T., Thun Michael J., Calle Eugenia E., Krewski Daniel, Ito Kazuhiko, Thurston George D. Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. JAMA. 2002 Mar 6;287(9):1132–1141. doi: 10.1001/jama.287.9.1132. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Rabl Ari. Interpretation of air pollution mortality: number of deaths or years of life lost? J Air Waste Manag Assoc. 2003 Jan;53(1):41–50. doi: 10.1080/10473289.2003.10466118. [DOI] [PubMed] [Google Scholar]
  15. Schwartz J. Harvesting and long term exposure effects in the relation between air pollution and mortality. Am J Epidemiol. 2000 Mar 1;151(5):440–448. doi: 10.1093/oxfordjournals.aje.a010228. [DOI] [PubMed] [Google Scholar]
  16. Stieb David M., Judek Stan, Burnett Richard T. Meta-analysis of time-series studies of air pollution and mortality: effects of gases and particles and the influence of cause of death, age, and season. J Air Waste Manag Assoc. 2002 Apr;52(4):470–484. doi: 10.1080/10473289.2002.10470794. [DOI] [PubMed] [Google Scholar]
  17. Tambay J. L., Catlin G. Sample design of the national population health survey. Health Rep. 1995;7(1):29-38, 31-42. [PubMed] [Google Scholar]
  18. Zanobetti Antonella, Schwartz Joel, Samoli Evi, Gryparis Alexandros, Touloumi Giota, Atkinson Richard, Le Tertre Alain, Bobros Janos, Celko Martin, Goren Ayana. The temporal pattern of mortality responses to air pollution: a multicity assessment of mortality displacement. Epidemiology. 2002 Jan;13(1):87–93. doi: 10.1097/00001648-200201000-00014. [DOI] [PubMed] [Google Scholar]
  19. Zeger S. L., Dominici F., Samet J. Harvesting-resistant estimates of air pollution effects on mortality. Epidemiology. 1999 Mar;10(2):171–175. [PubMed] [Google Scholar]
  20. Zeger S. L., Thomas D., Dominici F., Samet J. M., Schwartz J., Dockery D., Cohen A. Exposure measurement error in time-series studies of air pollution: concepts and consequences. Environ Health Perspect. 2000 May;108(5):419–426. doi: 10.1289/ehp.00108419. [DOI] [PMC free article] [PubMed] [Google Scholar]

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