Proximity to Traffic, Inflammation and Immune Function among Women in the Seattle Area
Lori A. Williams, Cornelia M. Ulrich, Timothy Larson,
Mark H. Wener, Brent Wood, Peter T. Campbell, John D. Potter,
Anne McTiernan, and Anneclaire J. De Roos
doi: 10.1289/ehp.11580 (available at http://dx.doi.org/)
Online 16 October 2008
Background:Traffic-related air pollution has been associated with adverse health outcomes and
the immune system may be a biologic mediator of health effects.
Objectives:We analyzed associations between living near major roads and immune status as
measured by five immune assays. We hypothesized that living near a freeway, arterial, or truck
route would be associated with increased inflammation and decreased immune function.
Methods:We used a geographic information system (GIS) to determine residential proximity to
major roads among 115 postmenopausal, overweight women in the greater Seattle, WA area
whose immunity was assessed at the baseline visit of an exercise intervention trial. We
evaluated three inflammatory markers (C-reactive protein, serum amyloid A and interleukin-6)
and two functional assays of cellular immunity (natural killer cell cytotoxicity and T-lymphocyte
Results:Women living within 150 meters of arterial roads had 21% lower natural killer cell
cytotoxicity compared to women who lived further from an arterial (mean cytotoxicity 19.5%;
95% confidence interval [15.6, 23.5] vs. mean cytotoxicity 24.8%; 95% confidence interval
[22.0, 27.5]), after adjustment for both individual-level and census-tract-level demographic
characteristics. This association was limited to women who reported exercising near traffic.
Fewer women lived near freeways and truck routes. Markers of inflammation and lymphocyte
proliferation did not consistently differ according to proximity to major roads.
Conclusions:If the observed association between residential proximity to traffic and decreased
natural killer cell cytotoxicity is confirmed in other populations, our results may have
implications for local land use policy.