Air pollution and hospitalization for bronchiolitis among young children

Rational: Several studies have found higher risks for childhood respiratory illness, associatedwith exposure to particulate matter (PM) less than 10 mm in diameter (PM10) and PM2.5 and gaseous pollution. Objectives: We analyzed the association between air pollution and hospitalizations due to bronchiolitis, an obstructive pulmonary disorder, commonly caused by respiratory syncytial virus infant infection. Methods: Data were obtained from a local tertiary medical center providing services for a population of 700,000 comprising two ethnic groups: predominantly urban Jews and rural Bedouin Arabs. The latter group includes 30% residing in unrecognized villages in a temporary dwelling.We included all infants (0-2 yr) hospitalized with bronchiolitis between 2003 and 2013. Daily PM estimates were obtained from a satellite-based model incorporating daily remote sensing data and assigned to the family residence locality. Other air pollutants and meteorological parameters were obtained from a local monitoring site. We used case-crossover models with adjustment for temperature. Results: We identified 4,069 bronchiolitis hospitalizations (3,889 children), with 55.3%being Bedouin Arabs, of whom16.8% resided in temporary dwellings. An increase in interquartile range of average weekly air pollutants was associated with an increased odds of bronchiolitis (odds ratio [95%confidence interval]):PM10 (1.06 [1.02- 1.09]), PM_2.5 (1.04 [1.02-1.06]) and nitrogen dioxide (1.36 [1.12- 1.65]). Higher effect-estimates for PM were observed among Bedouin Arabs residing in temporary dwellings (1.14 [1.01-1.30] and 1.07 [1.01-1.15]) compared with Jewish individuals (1.05 [0.99-1.11] and 1.03 [1.01-1.07]) and other Bedouin Arabs (1.05 [1.01-1.10] and 1.03 [1.01-1.07]), andamongmales (1.11 [1.06-1.16] and 1.06 [1.03-1.09]) compared with females (0.99 [0.94-1.05] and 1.01 [0.97-1.04]). Conclusions: High PM levels were positively associated with bronchiolitis. The stronger associations among Bedouin Arabs may be related to higher pollution infiltration and exposure in residents of temporary dwellings.