Studies Show Respiratory Effects on Children of Proximity to Highways
A study performed at Harbor-UCLA Medical Center has demonstrated a statistically significant inverse relationship between school proximity to highways and asthma prevalence and control. The study was presented at the annual meeting of the American Academy of Allergy, Asthma and Immunology in New Orleans.
There is growing body of data showing adverse respiratory health effects in children living who live near heavily trafficked roads But school age children spend the majority of their daytime hours at school, and say the researchers, "to the best of our knowledge, no large-scale studies have evaluated the association between school distance to nearby freeways and asthma prevalence and control."
The researchers used a bilingual, seven-question, self-administered asthma screening survey to identify children with asthma and with likelihood of poor disease control (sensitivity 86.5%, specificity 83.6%). Results were correlated with the shortest linear distance between a child’s school and the nearest major freeway.
The researchers analyzed 10,874 surveys from 739 classrooms in 20 inner-city elementary schools. They were able to identify 2530 (23.3%) elementary school children likely to have asthma, of whom 1316 (52%) were likely to have controlled asthma. Of 1214 (48%) children likely to have uncontrolled asthma, 768 (63%) were likely to have moderate-to-severe disease activity. Children attending schools within two miles of a major freeway had increased likelihood of asthma detection (P<0.0001) compared with children who attended schools greater than two miles from the nearest major freeway.
Similarly, for children likely to have asthma, attending schools within two miles of a freeway was associated with an increased incidence of uncontrolled asthma (P=0.005) and moderate-to-severe disease (P=0.005).
A related study was reported on by Columbia researchers. They studied 346 participants from the Columbia Center for Children’s Environmental Health birth cohort. Spatial data on distance to roadways, length of roadways, and density of roadways and intersections were collected for a 0.25 km radial buffer around subjects' homes at ages 1, 2, 3, and 5 years.
A 0.36 km (interquartile range) increase in length of highways and a 2.3 km increase in trucking route density were associated with 12% (P=0.05) and 14% (P=0.01), respectively, increased probability of cough in the previous 12 months. A 0.78 km increase in length of state/county roadways was associated with a 34% increased probability of reported doctor-diagnosed asthma (P=0.01).