Table 4

Associations between air pollutants and preterm births, Sydney, 1998–2000

Pollutant
Exposure period



One month preceding birth
Three months preceding birth
First month of gestation
First trimester



Sydney OR‡ 95% CI
5 km OR 95% CI
Sydney OR 95% CI
5 km OR 95% CI
Sydney OR 95% CI
5 km OR 95% CI
Sydney OR 95% CI
5 km OR 95% CI

PM10 24 hour average
0.991 0.979–1.003
1.008 0.993–1.022
0.989 0.975–1.004
1.012 0.995–1.030
0.983** 0.973–0.993
0.957 0.914–1.002
0.987 0.973–1.001
1.009 0.978–1.041
PM2.5 24 hour average
0.984 0.962–1.008
1.042 0.997–1.089
0.981 0.952–1.011
1.111** 1.037–1.189
0.981 0.962–1.000
1.032 0.897–1.188
0.978 0.950–1.007
0.991 0.929–1.057
O3 1-hour maximum
0.998 0.987–1.006
0.984 0.906–1.069
0.998 0.989–1.007
1.011 0.910–1.124
1.004 0.995–1.012
1.604** 1.268–2.030
1.014** 1.005–1.022
0.807* 0.668–0.976
NO21 hour maximum
1.000 0.990–1.011
0.996 0.881–1.126
1.006 0.993–1.019
1.046 0.913–1.205
0.967** 0.958–0.975
0.589* 0.360–0.963
0.970** 0.959–0.980
1.052 0.741–1.493
CO 8 hour maximum
0.962 0.889–1.042
1.000 0.864–1.158
0.997 0.907–1.096
1.111 0.942–1.310
0.896** 0.842–0.953
1.030 0.685–1.548
0.774** 0.715–0.838
1.247 0.811–1.917
SO2 1 hour maximum
0.993 0.948–1.040
1.557* 1.017–2.382
0.977 0.898–1.063
2.330** 1.344–4.040
0.856** 0.819–0.894
1.378 0.876–2.167
0.834** 0.777–0.895
2.312** 1.290–4.145

‡OR estimates adjusted for: maternal age, maternal smoking during pregnancy, indigenous status, SES, gestational age at first antenatal visit, season of conception and parity. OR is for a one unit increase in air pollutant concentration; *p < 0.05; **p < 0.01

Jalaludin et al. Environmental Health 2007 6:16   doi:10.1186/1476-069X-6-16