Table 3.

The effect of air pollution on stillbirth in Tehran

Relative Risk (95% Confidence Interval)
Lag (day)	10 μg/m3 increase in PM2.5	10 ppb increase in NO2	10 ppb increase in O3	5 ppb increase in SO2	1 ppm increase in CO
0	1.009 (0.989–1.029)	1.008 (0.990–1.026)	0.994 (0.955–1.034)	1.062 (1.002–1.125)	1.007 (0.972–1.044)
1	1.004 (0.994–1.015)	1.004 (0.995–1.014)	0.993 (0.970–1.017)	1.028 (0.993–1.064)	1.003 (0.983–1.024)
2	1.001 (0.992–1.009)	1.002 (0.995–1.009)	0.994 (0.975–1.012)	1.005 (0.979–1.032)	0.999 (0.985–1.015)
3	0.999 (0.991–1.007)	1.000 (0.993–1.007)	0.994 (0.976–1.012)	0.991 (0.966–1.018)	0.997 (0.982–1.012)
4	0.998 (0.989–1.006)	0.999 (0.991–1.006)	0.994 (0.977–1.013)	0.984 (0.958–1.010)	0.995 (0.980–1.010)
5	0.998 (0.990–1.005)	0.998 (0.991–1.005)	0.995 (0.978–1.012)	0.980 (0.956–1.006)	0.993 (0.979–1.007)
6	0.998 (0.991–1.005)	0.998 (0.991–1.004)	0.995 (0.979–1.011)	0.980 (0.957–1.004)	0.992 (0.980–1.005)
7	0.998 (0.992–1.005)	0.997 (0.992–1.003)	0.996 (0.981–1.010)	0.982 (0.959–1.006)	0.992 (0.980–1.004)