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TRAFFIC-RELATED AIR POLLUTION AND CHILDREN'S RESPIRATORY HEALTH: BEYOND PROXIMITY TO MAJOR ROADWAYS
Citation:
JOHNSON, M. M., L. M. NEAS, S. MUKERJEE, AND C. STALLINGS. TRAFFIC-RELATED AIR POLLUTION AND CHILDREN'S RESPIRATORY HEALTH: BEYOND PROXIMITY TO MAJOR ROADWAYS. Presented at International Society for Environmental Epidemiology Annual Meeting, Paris, FRANCE, September 02 - 06, 2006.
Description:
Introduction: Previous studies of the respiratory health impact of mobile source air pollutants on
children have relied heavily on simple exposure metrics such as proximity to roadways and traffic
density near the home or school. Few studies have conducted area-wide monitoring of indicator
pollutants coupled with land-use regression modeling for exposure assessment. Based largely
on proximity studies, the State of California (U.S.) has restricted the location of new schools
within 500ft (168m) from a roadway averaging 50,000 or more vehicles per day (>50k-vpd) in
rural and >100k-vpd in urban areas. We examined adverse effects of mobile source emissions
among children living outside California¿s buffer area using both simple exposure metrics and a
land-use regression modeling approach.
Methods: The El Paso Children¿s Health Study was a cross -sectional study of children enrolled
in the fourth and fifth grades of public elementary schools in El Paso, Texas. Measurements of
nitrogen dioxide were made at 22 elementary schools. Ambient NO2 concentration, an indicator
of mobile source emissions, was estimated at each child¿s residence using a land-use regression
model. For this analysis, we restricted the cohort to 62% of the children (n=2546) who lived
outside the Rio Grand River valley (above 1700m). None of these children lived within 200m of a
roadway with >90k-vpd; only 3.2% lived within 200m of a roadway with >50k-vpd; however,
almost half lived within 200m of a roadway with >10k-vpd. Epidemiologic models were adjusted
for demographic, socioeconomic, parental, and random school effects.
Results: As expected from a GIS-based model, estimated NO2 concentration increased by
4.8ppb [95%CI: 2.7, 6.8], 3.2ppb [2.7, 3.7], and 2.6ppb [2.4, 2.9] per km increase in proximity to
>10k, >50k, and >90k-vpd roadways, respectively. NO2 concentration estimated through landuse
regression modeling was positively associated with current asthma (OR=1.7 [1.1, 2.6] for
10ppb NO2). Proximity to roadways with >50k-vpd was positively associated with current asthma
(OR =1.1 [1.02, 1.2] for 1.5km). There were also marginally significant associati ons between
current asthma and proximity to roadways with >10k and >90k-vpd (OR =1.5 [0.97, 2.4] for 1.5km
and OR =1.04 [1.0, 1.1] for 1.5km, respectively).
Discussion and Conclusions: These results provide evidence that adverse health affects
associated with traffic-related air pollution occur well beyond a narrow (200m) buffer area
surrounding major roadways, potentially impacting children living several kilometers away from
these roadways.
This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.