Indoor- and outdoor-generated particles: Koenig et al. respond.
In our article (Koenig et al. 2005), we stated that indoor sources are known to affect airway inflammation. We recognized that indoor sources vary greatly and that 19 homes may not provide a sufficient sample size to allow for a robust association. It is true that the children in our study spent substantial time away from home. We now have additional data from a panel of 16 adults (average age of 75 years) who did not commute or leave home regularly; in these adults we found the same coefficient with eNO (exhaled nitric oxide) versus outdoor P[M.sub.2.5] (particulate matter [less than or equal to] 2.5 [micro]m in aerodynamic diameter) as in the research in question (Jansen et al. 2004). In addition, Ebelt et al. (2005) found lung function decrements only with ambient particles in a group of nonsmoking 54- to 86-year-old adults. These results provide additional evidence of an ambient-only pulmonary effect among individuals who spent relatively little time away from home.
Regarding smoking status, one inclusionary criterion for our study was to be a nonsmoker and live with nonsmokers; thus smoking is not an important indoor source of particles in these residences. Children in the Seattle school district do not go home for lunch. However, it is true that our exhaled breath samples were taken 1-2 hr after the commute home (Liu et at. 2003). On average, the time between morning commute and eNO collection was 9 hr; between afternoon commute and breath collection was about 2 hr. We are now looking at the short-term lag structure. Using a polynomial distributed lag model, we found that P[M.sub.2.5] was associated with the eNO for up to 10-12 hr before the eNO measurement (Mar et at., in press).
The authors declare they have no competing financial interests.
Ebelt ST, Wilson WE, Brauer M. 2005. Exposure to ambient and nonambient components of particulate matter: a comparison of health effects. Epidemiology 16:396-405.
Jansen K, Koenig JQ, Larson TV, Fields C, Mar TF, Stewart J, et al. 2004. Nitric oxide in subjects with respiratory disease is associated with PM25 and black carbon in Seattle [Abstract]. Am J Respir Crit Care Med 169:A282.
Koenig JQ, Mar TF, Allen RW, Jansen K, Lumley T, Sullivan JH, et al. 2005. Pulmonary effects of indoor- and outdoor-generated particles in children with asthma. Environ Health Perspect 113:499-503.
Liu L-JS, Box M, Kalman D, Kaufman J, Koenig J, Larson T, et al. 2003. Exposure assessment of particulate matter for susceptible populations in Seattle, WA. Environ Health Perspect 111:909-918.
Mar TF, Jansen K, Shepherd K, Lumley T, Larson TV, Koenig JQ. In press. Exhaled nitric oxide in children with asthma and short term PM exposure in Seattle. Environ Health Perspect.
University of Washington
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|Title Annotation:||Perspectives / Correspondence|
|Publication:||Environmental Health Perspectives|
|Date:||Sep 1, 2005|
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