Academic journal article Environmental Health Perspectives

Ozone and P[M.Sub.2.5] Exposure and Acute Pulmonary Health Effects: A Study of Hikers in the Great Smoky Mountains National Park

Academic journal article Environmental Health Perspectives

Ozone and P[M.Sub.2.5] Exposure and Acute Pulmonary Health Effects: A Study of Hikers in the Great Smoky Mountains National Park

Article excerpt

To address the lack of research on the pulmonary health effects of ozone and fine particulate matter ([less than or equal to] 2.5 [micro]m in aerodynamic diameter; P[M.sub.2.5]) on individuals who recreate in the Great Smoky Mountains National Park (USA) and to replicate a study performed at Mt. Washington, New Hampshire (USA), we conducted an observational study of adult (18-82 years of age) day hikers of the Charlies Bunion trail during 71 days of fall 2002 and summer 2003. Volunteer hikers performed pre- and posthike pulmonary function tests (spirometry), and we continuously monitored ambient [O.sub.3], P[M.sub.2.5], temperature, and relative humidity at the trailhead. Of the 817 hikers who participated, 354 (43%) met inclusion criteria (nonsmokers and no use of bronchodilators within 48 hr) and gave acceptable and reproducible spirometry. For these 354 hikers, we calculated the posthike percentage change in forced vital capacity (FVC), forced expiratory volume in 1 sec (FE[V.sub.1]), FVC/FE[V.sub.1], peak expiratory flow, and mean flow rate between 25 and 75% of the FVC and regressed each separately against pollutant ([O.sub.3] or P[M.sub.2.5]) concentration, adjusting for age, sex, hours hiked, smoking status (former vs. never), history of asthma or wheeze symptoms, hike load, reaching the summit, and mean daily temperature. [O.sub.3] and P[M.sub.2.5] concentrations measured during the study were below the current federal standards, and we found no significant associations of acute changes in pulmonary function with either pollutant. These findings are contrasted with those in the Mt. Washington study to examine the hypothesis that pulmonary health effects are associated with exposure to [O.sub.3] and P[M.sub.2.5] in healthy adults engaged in moderate exercise. Key words: air pollution epidemiology, fine particulate matter exposure, Great Smoky Mountains National Park, ozone exposure, pulmonary function, spirometry. Environ Health Perspect 114:1044-1052 (2006). doi:10.1289/ehp.8637 available via http://dx.doi.org/ [Online 9 February 2006]

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Both observational studies and controlled-chamber studies have been used to assess acute effects of air pollution on lung function in adults engaged in exercise or work (Aris et al. 1991; Avol et al. 1984; Brunekreef et al. 1994; Folinsbee et al. 1984, 1988; Gong et al. 1986; Hazucha 1987; Horstman et al. 1990; Kinney et al. 1996; Korrick et al. 1998; McBride et al. 1994; McDonnell et al. 1993, 1995, 1997; Naeher et al. 1999; Pekkanen et al. 2002; Selwyn et al. 1985; Spektor et al. 1988; Torres et al. 1997). Although fewer in number, observational studies offer the advantage of studying the effects of pollution on humans engaged in "real-world" activities in natural settings (Thurston and Ito 2001). However, they also have significant methodologic challenges. These include a) identifying an accessible population at risk whose exposures can be defined and adequately characterized, b) specifying measurable health outcomes, c) collecting an adequate amount of suitable quality-assured data on exposure and health outcomes, d) collecting sufficient data on other factors that may influence the exposure-outcome relationship, and e) the logistical issues of employing properly trained and motivated field technicians, finding cooperative subjects, and having a large enough sample size to adequately power the statistical analyses (Lippmann 1989).

In 1992 and 1993, Harvard University researchers performed a large observational study of day hikers at Mt. Washington in the White Mountain National forest of New Hampshire (Korrick et al. 1998). The Mt. Washington area is a popular site for outdoor recreation but is plagued with episodically high levels of ozone and fine particulate matter ([less than or equal to] 2.5 [micro]m in aerodynamic diameter; P[M.sub.2.5]) due to transported air pollutants and their precursors from surrounding industrial and urban areas (Korrick et al. …

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