Table 1 Description of study population: lifetime never-smokers with and without incident asthma at SAPALDIA 2
No asthma(N = 2684)New-onset asthma(N = 41)Total(N = 2725)p Value†
Age at baseline ⩽40 years (%)48.5563.4148.770.059
Women (%)61.3663.4161.390.789
Bronchial hyperreactivity at baseline (missing, n = 506) (%)7.0117.147.170.021
Atopy at baseline (missing, n = 244) (%)28.4160.0028.86<0.001
Maternal allergies at baseline (%)15.227.5015.100.176
FEV1 at baseline ⩽85% predicted (%)2.612.442.610.946
Work exposure to dast/fumes at baseline (%)29.6537.5029.760.281
Environmental tobacco smoke at home at baseline (%)15.0914.6315.080.936
Age ending full-time education ⩽20 years (%)66.2065.8566.200.963
Main street within 20 m (SAPALDIA 1 address) (%)18.8317.0718.810.775
Mean (SD) age at follow-up (years)50.83 (12.25)45.35 (11.58)50.74 (12.26)0.005
Mean (SD) BMI at baseline23.50 (3.65)23.67 (3.22)23.50 (3.64)0.583
Mean (SD) FEV1 %predicted at baseline123.11 (24.93)116.17 (17.60)123.00 (24.85)0.120
Mean (SD) traffic PM10 at SAPALDIA 12.84 (1.80)2.42 (1.61)2.84 (1.80)0.120
Mean (SD) traffic PM10 at SAPALDIA 22.25 (1.43)2.17 (1.43)2.25 (1.43)0.126
Mean (SD) total PM10 at SAPALDIA 127.68 (10.03)26.46 (10.32)27.66 (10.04)0.393
Mean (SD) total PM10 at SAPALDIA 221.45 (7.17)21.41 (7.90)21.45 (7.18)0.440
Mean (SD) change in total PM10−6.23 (4.40)−5.05 (5.02)−6.21 (4.41)0.619
Change in traffic PM10 (μg/m3) (main exposure metric)−0.59 (1.13)−0.25 (1.40)−0.59 (1.14)
    25th percentile−0.80−0.61−0.80
    50th percentile−0.39−0.30−0.39
    75th percentile−0.21−0.11−0.21
    Interquartile range0.590.500.59
  • BMI, body mass index; FEV1, forced expiratory volume in 1 s; PM10, particulate matter up to 10 μm in diameter; SAPALDIA, Swiss Cohort Study on Air Pollution and Lung Diseases in Adults.

  • †p Value for χ2 test or Kruskal-Wallis test comparing the two groups.