Table 2.

Findings from recent publications examining the effects of air pollution on asthma outcomes

Reference	Study Design	Age (years)	Exposure Assessment	N	Pollutants	Outcomes	Notes
Farber et al, 2016 (8*)	Cross sectional	<18	Survey	22,470	Secondhand smoke	Significant association between SHS and ED visits in children whose mothers smoke
Tetreault et al, 2016 (9)	Retrospective cohort	<13	Daily average levels linked to postal code of residence	162,752	NO2, PM2.5, O3	Positive association between time-dependent exposure to pollutants and asthma exacerbation frequency	Stronger association with long term exposure than exposure at birth.
Schvartsman et al, 2017 (10)	Ecological time-series	<19	Daily average city-wide levels of pollutants	20,958 visits	O3, CO, NO2, SO2, PM10	Increase in PM10 and SO2 daily levels positively correlated with number of ED visits for asthma; 7-day cumulative effect of PM10 and SO2 on ED visits was much higher	Cumulative exposure had much larger effect on asthma-related ED visits than did same day exposure
Orellano et al, 2017 (11)	Systematic review	0–80	Multiple	267,415	NO2, SO2, PM10, PM2.5, CO, O3	Subgroup analysis showed significant association between NO2, SO2, and PM2.5 and pediatric asthma exacerbations
Ding et al, 2017 (12)	Case crossover	0–18	Daily average city-wide levels of pollutants	2,507 visits	PM10, PM2.5, SO2, NO2, CO, O3	Increase of 10 μg/m3 in PM10, PM2.5, SO2, NO2, CO were positively associated with asthma-related hospital visits	No association between asthma-related hospital visits and O3
Goodman et al, 2017 (13)	Time-series analysis	5 to >65	Area-specific daily average 8h maximum O3 concentration	74,824 hospital admiss-ions	O3	Positive correlation between pediatric asthma-related hospitalization and short-term O3 exposure	Association was strongest in August and September, correlating with start of school year