Effects of web-based behavioral intervention on fine particulate matter, pulmonary function, and airway inflammation in children: The COCOA randomized controlled trial.

Background: Although web-based intervention programs are effective in changing health behavior, evidence of their effectiveness in relation to air pollution and respiratory health in children is lacking. We assessed the effects of web-based behavioral intervention on exposure to fine particulate matter (PM ≤ 2.5 μm in diameter [PM]), lung function, and airway inflammation in children.

Methods: We randomized 80 mother-child pairs into intervention or control groups (two arms, 1:1 allocation). Personal and indoor PM concentrations over a sampling period of 24 h up to four occasions during the study period were measured in participants' homes. We used linear mixed models to assess the intervention effects on PM concentration, lung function parameters including forced vital capacity (FVC), forced-expiratory volume in 1 s (FEV1), FEV1/FVC, and forced-expiratory flow at 25-75 % (FEF), and the airway inflammation marker, fractional exhaled nitric oxide (FeNO), as well as the association of PM with lung function and airway inflammation. Quantile regression was also used to examine the effects of PM exposure at different quantiles of the outcome distribution.

Results: In comparison with the control group, the intervention group showed reduction in indoor and personal PM concentrations by 20.5 % (95 % confidence interval [CI]: -30.7, -8.9) and 12.9 % (95 % CI: -20.1, -5.1), respectively. Lung function parameters such as FVC, FEV1, and FEF were higher in the intervention group, with greater benefits observed for children at the lower end of these parameters. Higher levels of outdoor and personal PM (≥90th percentile) were negatively associated with these lung function parameters at the lower quantiles, whereas the higher level of outdoor PM concentration was positively associated with FeNO at the lower quantile.

Conclusions: The behavioral intervention reduced PM concentration in the homes, which was linked to markers of lung function and airway inflammation in children, particularly at the lower quantiles.