Table 2.

Association between exposure to traffic related air pollutants in pregnancy and asthma development

References	Type of study, Country	Subjects, no	Pollutants and exposure assessment	Outcome	Positive association with the outcome	Sensitivity windows
Lavigne E et al., 2019 [14]	Registry-based birth cohort, Toronto, Canada	160,641	UFPs, PM2.5, NO2 Daily exposure	Asthma (birth up to < 6 years)	Yes	Second trimester
Jung CR et al., 2019 [15]	TMCHD registry-based birth cohort, Taiwan	184,604	PM2.5 Daily exposure	Asthma (birth up to 3–10 years)	Yes	Weeks 6–22
Lavigne E et al., 2018 [16]	Registry-based birth cohort, Ontario, Canada	222,864	PM2.5, NO2 Daily exposure	Asthma (birth up to < 6 years)	Yes	Second trimester
Pennington AF et al., 2018 [17]	KAPPA, registry-based birth cohort, Atlanta, USA	19,951	PM2.5, NOx, CO Annual average	Asthma (2 to 6 years)	Yes	NA
Lee A et al., 2018 [18]	ACCESS pregnancy cohort, Boston, USA	736	PM2.5 Daily exposure	Asthma (birth up to 6 years)	Yes	Weeks 19–23 in exposed to maternal prenatal stress
Bose S et al., 2017 [19]	ACCESS pregnancy cohort, Boston, USA	752	NO3− Daily exposure	Asthma (birth up to 6 years)	Yes in boys exposed to prenatal maternal stress	7–19 and 33–40 weeks
Sbihi H et al., 2017 [20]	Registry-based birth cohort, Vancouver, Canada	65,254	NO2, PM2.5 Daily exposure aggregated over the pregnancy period	Asthma trajectories (birth up to 7–10 years)	Yes	NA
Sbihi H et al., 2016 [21]	Case-control nested in a registry-based birth cohort, Vancouver, Canada	Pre-schoolers: 6948 cases, 34,621 controls; School-age: 1711 and 8577	BC, CO, NO, NO2, PM2.5, PM10 Daily exposure aggregated over the pregnancy period	Asthma (birth up to 6–10 years)	Yes only in preschoolers and only for PM10	NA

BC Black carbon, CO Carbon monoxide, PM_2.5 Particulate matter < 2.5 μm in diameter, PM₁₀ Particulate matter < 10 μm in diameter; NO_x Nitrogen oxides, NO Nitric oxide, NO₂ Nitrogen dioxide, NO₃ Nitrate, UFPs Ultra-Fine Particles ≤ 0.1 μm in diameter; NA Not assessed