Table 2.

Risk differences and 95% confidence intervals for prenatal and first year of life mobile source PM_2.5 and asthma incidence

Prenatal exposure, RD per natural log increase^a

Cohort	Unadjusted RD (95% CI)	Adjusted RD (95% CI)
Age 2	−0.007 (−0.017, 0.002)	0.015 (0.003, 0.027)
Age 3	−0.008 (−0.021, 0.005)	0.018 (0.002, 0.035)
Age 4	−0.008 (−0.025, 0.009)	0.023 (0.001, 0.044)
Age 5	0.001 (−0.019, 0.021)	0.032 (0.007, 0.058)
Age 6	0.005 (−0.019, 0.029)	0.035 (0.006, 0.065)

First year of life exposure, RD per natural log increase^a

Cohort	Unadjusted RD (95% CI)	Adjusted RD (95% CI)

Age 2	−0.008 (−0.016, 0.001)	0.012 (0.000, 0.023)
Age 3	−0.009 (−0.021, 0.004)	0.019 (0.003, 0.034)^b
Age 4	−0.008 (−0.024, 0.007)	0.025 (0.004, 0.046)
Age 5	0.005 (−0.014, 0.024)	0.041 (0.016, 0.066)
Age 6	0.002 (−0.021, 0.024)	0.035 (0.005, 0.064)

RD indicates risk difference, CI confidence interval. Adjusted models control for child sex, child race, maternal asthma, birth year, neighborhood socioeconomic status, and city region.

This represents the absolute change in risk per 2.7-fold increase in mobile source PM_2.5 concentration (μg/m³)

birth year replaced by cubic splines on date of birth with 1 knot per year.

Adjusted model age 5 results are graphically presented in Figure 3. Corresponding results for NO_X and CO are listed in eTable 1.