Table 2

Lung function indices (with 95% CI) of non-smoking catering workers and indoor workplace PM2.5 concentrations expressed with the associated probability of permitted indoor smoking

PM2.5 (μg/m3)n0n1FEV1 (l)FEF25–75 (l/s)FEV1/FVC (%)
All workers (n=186)
 ≤25300000
 25–75523−0.072 (−0.123 to −0.021)**−0.368 (−0.660 to −0.077)*−0.029 (−0.048 to −0.010)**
 75–1754419−0.078 (−0.132 to −0.024)**−0.489 (−0.799 to −0.179)**−0.032 (−0.051 to −0.014)***
 >1751424−0.101 (−0.187 to −0.014)*−0.597 (−0.943 to −0.251)**−0.044 (−0.074 to −0.013)**
p for trend=0.025p for trend=0.003p for trend=0.007
Workers who never smoked (n=156)
 ≤25250000
 25–75413−0.092 (−0.150 to −0.035)**−0.414 (−0.714 to −0.113)**−0.035 (−0.058 to −0.012)**
 75–1754015−0.093 (−0.153 to −0.034)**−0.482 (−0.814 to −0.150)**−0.037 (−0.057 to −0.017)***
 >1751418−0.106 (−0.218 to 0.006)−0.563 (−0.990 to −0.136)**−0.043 (−0.082 to −0.005)*
p for trend=0.030p for trend=0.006p for trend=0.014
Workers aged ≥30 (n=113)
 ≤25260000
 25–75372−0.082 (−0.146 to −0.018)*−0.548 (−0.807 to −0.289)***−0.032 (−0.054 to −0.009)**
 75–175278−0.070 (−0.137 to −0.004)*−0.629 (−0.956 to −0.302)***−0.030 (−0.051 to −0.008)**
 >17567−0.220 (−0.365 to −0.074)**−1.242 (−1.773 to −0.710)***−0.097 (−0.150 to −0.044)***
p for trend<0.001p for trend<0.001p for trend<0.001
Workers in non-smoking premises (n=140)
 ≤25300000
 25–75520−0.088 (−0.140 to −0.035)***−0.460 (−0.745 to −0.175)**−0.040 (−0.061 to −0.019)***
 75–175440−0.097 (−0.160 to −0.033)**−0.544 (−0.928 to −0.161)**−0.040 (−0.062 to −0.019)***
 >175140−0.183 (−0.320 to −0.046)**−0.888 (−1.381 to −0.395)***−0.081 (−0.128 to −0.034)***
p for trend=0.029p for trend=0.011p for trend=0.008
Workers not exposed to co-workers' SHS (n=72)
 ≤25150000
 25–75230−0.099 (−0.183 to −0.015)*−0.392 (−0.755 to −0.028)*−0.045 (−0.076 to −0.013)**
 75–175224−0.144 (−0.217 to −0.070)***−0.705 (−1.039 to −0.371)***−0.064 (−0.086 to −0.043)***
 >17580−0.231 (−0.400 to −0.061)**−1.186 (−1.801 to −0.570)***−0.100 (−0.155 to −0.045)***
p for trend<0.001p for trend<0.001p for trend<0.001

  • *p<0.05; **p<0.01; ***p<0.001 (F-test).

  • Estimates were adjusted for gender, age, height, duration of SHS exposure at work, daily duration of SHS exposure at home and in other places, education, income, job position, the effect of patio seating and FVC where appropriate.

  • FEV1, forced expiratory volume in 1 s; FEF25–75, forced expiratory flow as 25–75% of FVC; FVC, forced vital capacity; n0, number of workers from non-smoking premises; n1, number of workers from smoking premises; SHS, second-hand smoke.