Table 4

Association between exposure to air pollution during the first year of life and incidence rate of lower respiratory tract infections during the first 2 years of life, incidence rate ratio (IRR) as the measure of effect

ExposureEffect estimates, IRR (95% CI), relative to the first quartilePer 10 µg/increase
Quartile 2Quartile 3Quartile 4IRR (95% CI)
PM2.5*1.23 (0.59 to 2.55)1.86 (0.91 to 3.80) 2.50 (1.27 to 4.93) 1.24 (0.63 to 2.43)
PM2.51.39 (0.67 to 2.92)1.66 (0.77 to 3.60) 2.92 (1.44 to 5.92) 1.70 (0.84 to 3.43)
+SO2 1.77 (0.68 to 4.59)1.69 (0.50 to 5.67)1.58 (0.41 to 6.16)1.23 (0.27 to 5.51)
+O3 1.49 (0.64 to 3.47)1.60 (0.57 to 4.46)2.56 (0.87 to 7.51)0.83 (0.32 to 2.19)
+SO2 +O3 1.90 (0.66 to 5.45)1.67 (0.42 to 6.56)1.54 (0.33 to 7.17)0.85 (0.20 to 3.67)
PM10*1.12 (0.54 to 2.33)1.90 (0.95 to 3.81) 2.42 (1.23 to 4.76) 1.20 (0.65 to 2.19)
PM101.23 (0.59 to 2.59)1.66 (0.79 to 3.51) 2.82 (1.40 to 5.70) 1.61 (0.85 to 3.04)
+ CO1.67 (0.69 to 4.06)2.26 (0.79 to 6.45) 3.38 (1.09 to 10.54) 1.17 (0.37 to 3.70)
+ NO2 1.91 (0.75 to 4.85)2.49 (0.79 to 7.87)2.97 (0.81 to 10.93)1.09 (0.25 to 4.74)
+ CO + O3 1.63 (0.59 to 4.53)1.96 (0.53 to 7.27)2.62 (0.60 to 11.44)0.68 (0.19 to 2.38)
+ NO2 + O3 1.83 (0.63 to 5.34)2.17 (0.54 to 8.67)2.30 (0.46 to 11.43)0.62 (0.13 to 2.98)
NO2*0.77 (0.38 to 1.58)1.85 (0.92 to 3.73) 2.31 (1.18 to 4.53) 1.58 (0.41 to 6.17)
NO20.83 (0.40 to 1.73)1.71 (0.81 to 3.61) 2.83 (1.40 to 5.71) 2.75 (0.64 to 11.82)
+ PM10 0.53 (0.21 to 1.34)0.89 (0.28 to 2.84)1.37 (0.35 to 5.32)3.91 (0.12 to 12.84)
+ O3 0.83 (0.38 to 1.82)1.46 (0.60 to 3.54)2.28 (0.86 to 6.06)0.78 (0.11 to 5.56)
+ PM10+ O3 0.57 (0.22 to 1.51)0.96 (0.29 to 3.15)1.53 (0.37 to 6.37)2.61 (0.07 to 91.97)
CO *0.97 (0.49 to 1.92)1.51 (0.74 to 3.05)1.79 (0.89 to 3.62)1.01 (0.96 to 1.06)
CO †0.92 (0.44 to 1.90)1.71 (0.82 to 3.58) 2.28 (1.09 to 4.74) 1.04 (0.98 to 1.10)
+ PM10 0.59 (0.24 to 1.45)0.87 (0.31 to 2.43)0.87 (0.27 to 2.84)1.05 (0.94 to 1.16)
+ O3 0.84 (0.39 to 1.79)1.33 (0.58 to 3.05)1.51 (0.61 to 3.71)1.00 (0.93 to 1.07)
+ SO2 0.53 (0.19 to 1.45)0.61 (0.19 to 1.98)0.39 (0.10 to 1.49)1.03 (0.94 to 1.13)
+ SO2 + O3 0.58 (0.21 to 1.59)0.68 (0.20 to 2.29)0.43 (0.11 to 1.69)1.02 (0.93 to 1.12)
+ PM10+ O3 0.64 (0.25 to 1.59)0.94 (0.32 to 2.70)0.95 (0.28 to 3.22)1.04 (0.93 to 1.15)
SO2*0.75 (0.36 to 1.57)1.21 (0.57 to 2.59) 2.49 (1.24 to 5.02) 1.40 (0.73 to 2.69)
SO20.80 (0.38 to 1.69)1.16 (0.52 to 2.61) 2.81 (1.35 to 5.83) 1.91 (0.92 to 3.96)
+ CO1.28 (0.47 to 3.47)2.05 (0.60 to 6.99)6.37 (1.68 to 24.15)1.87 (0.65 to 5.39)
+ NO2 1.52 (0.55 to 4.19)2.68 (0.72 to 10.00)7.89 (1.74 to 35.72)2.05 (0.63 to 6.66)
+ O3 0.81 (0.37 to 1.77)1.14 (0.44 to 2.95)2.71 (0.98 to 7.51)0.99 (0.35 to 2.79)
+ CO + O3 1.16 (0.40 to 3.37)1.79 (0.44 to 7.32)5.62 (1.14 to 27.80)1.02 (0.27 to 3.86)
+NO2 + O3 1.40 (0.48 to 4.09)2.37 (0.55 to 10.12)6.71 (1.21 to 37.05)1.14 (0.28 to 4.71)
O3*0.81 (0.48 to 1.38)0.49 (0.26 to 0.93)0.49 (0.26 to 0.92)0.49 (0.22 to 1.11)
O30.79 (0.45 to 1.39)0.54 (0.27 to 1.07)0.55 (0.29 to 1.06)0.58 (0.24 to 1.36)
+ SO2 1.11 (0.58 to 2.12)0.82 (0.35 to 1.95)0.85 (0.33 to 2.19)0.25 (0.07 to 0.91)
+ NO2 0.94 (0.49 to 1.81)0.65 (0.29 to 1.47)0.62 (0.26 to 1.50)0.29 (0.09 to 0.94)
+ CO0.83 (0.44 to 1.54)0.58 (0.27 to 1.24)0.56 (0.25 to 1.29)0.33 (0.10 to 1.02)
+ PM2.5 1.02 (0.53 to 1.94)0.76 (0.31 to 1.83)0.87 (0.32 to 2.36)0.26 (0.08 to 0.86)
+ SO2 + CO1.08 (0.56 to 2.09)0.89 (0.38 to 2.08)0.91 (0.35 to 2.36)0.25 (0.07 to 0.91)
+ PM10 + NO2 0.98 (0.50 to 1.93)0.75 (0.31 to 1.80)0.82 (0.30 to 2.25)0.25 (0.08 to 0.85)
+ PM2.5 + SO2 1.14 (0.58 to 2.24)0.83 (0.33 to 2.07)0.94 (0.33 to 2.63)0.23 (0.06 to 0.84)
+ NO2 + SO2 1.03 (0.53 to 2.01)0.87 (0.37 to 2.05)0.87 (0.33 to 2.26)0.25 (0.07 to 0.90)
  • *Single pollutant models, adjusted only for prenatal exposure of respective pollutant.

  • †Adjusted for prenatal exposure of respective pollutants and covariates in table 1.

  • CO, carbon monoxide; IRR, incidence rate ratio; NO2, nitrogen dioxide; O3, ozone; PM10, particulate matter with a diameter of 10 μm; PM2.5, particulate matter with a diameter of 2.5 μm; SO2, sulfur dioxide.