Table 5

 Association between long-term exposure to air pollution and lifetime prevalences of infections, asthmatic and allergic symptoms

Exposure variableAdjusted* odds ratios of symptoms associated with interquartile range of air pollution variables (symptom variable)
WheezeCough without infectionDry cough at nightAsthmatic/spastic/obstructive bronchitisRespiratory infectionsSneezing, runny/stuffed nose
NA, not applicable; NO2, nitrogen dioxide; PM2.5, particulate matter with a 50% cut-off aerodynamic diameter of 2.5 µm.
*Adjusted for sex, parental atopy, maternal education, siblings, environmental tobacco smoke at home, use of gas for cooking, home dampness, indoor moulds and keeping pets.
At the age of 1 year
n = 3037n = 2908n = 3056n = 3059n = 3052n = 3067
PM2.5 (per 1.04 μg/m3)1.01 (0.87 to 1.18)1.05 (0.88 to 1.25)1.08 (0.86 to 1.27)1.04 (0.90 to 1.29)1.05 (0.88 to 1.22)1.16 (1.01 to 1.34)
PM2.5 absorbance (per 0.22×10−5/m)0.97 (0.77 to 1.23)1.16 (0.87 to 1.54)1.09 (0.78 to 1.51)1.14 (0.88 to 1.48)1.03 (0.86 to 1.24)1.30 (1.03 to 1.65)
NO2 (per 5.7 μg/m3)1.09 (0.88 to 1.35)1.15 (0.88 to 1.51)1.34 (1.00 to 1.81)1.30 (1.03 to 1.66)1.06 (0.89 to 1.26)1.14 (0.90 to 1.43)
Distance to nearest main road <50 m (yes v no)1.14 (0.92 to 1.42)0.74 (0.55 to 1.00)0.84 (0.61 to 1.16)1.12 (0.88 to 1.44)1.03 (0.86 to 1.23)1.10 (0.87 to 1.39)
At the age of 2 years
n = 2882n = 2866n = 2861n = 3021n = 2907
PM2.5 (per 1.04 µg/m3)1.10 (0.96 to 1.25)NA1.03 (0.89 to 1.19)1.05 (0.92 to 1.20)1.09 (0.94 to 1.27)1.19 (1.04 to 1.36)
PM2.5 absorbance (per 0.22×10−5/m)1.09 (0.90 to 1.33)NA1.18 (0.93 to 1.50)0.85 (0.31 to 2.34)1.05 (0.79 to 1.39)1.27 (1.04 to 1.56)
NO2 (per 5.7 μg/m3)1.09 (0.90 to 1.31)NA1.16 (0.92 to 1.47)0.82 (0.33 to 2.03)1.08 (0.83 to 1.42)1.09 (0.89 to 1.33)
Distance to nearest main road <50 m (yes v no)1.06 (0.88 to 1.27)NA0.93 (0.73 to 1.18)1.23 (1.00 to 1.51)1.15 (0.87 to 1.53)1.24 (1.01 to 1.51)