Table 2.

Combined relative risks and 95% confidence intervals in single- and two-pollutant models.

Primary exposure	Adjustment of another pollutant	RRa (95% CI)
${\text{NO}}_2$	No adjustment	1.019 (0.999, 1.039)
	${\text{SO}}_2$	1.014 (0.990, 1.040)
	${\mathrm{PM}}_{10}$	1.015 (0.986, 1.045)
${\text{SO}}_2$	No adjustment	1.020 (1.006, 1.035)
	${\text{NO}}_2$	1.012 (0.995, 1.029)
	${\mathrm{PM}}_{10}$	1.014 (0.995, 1.034)
${\mathrm{PM}}_{10}$	No adjustment	1.016 (1.004, 1.029)
	${\text{NO}}_2$	1.011 (0.995, 1.026)
	${\text{SO}}_2$	1.014 (1.000, 1.029)
${\mathrm{PM}}_{2.5}$	No adjustment	1.017 (0.977 1.058)
	${\text{NO}}_2$	1.022 (0.970, 1.078)
	${\text{SO}}_2$	1.012 (0.986, 1.037)
${\mathrm{PM}}_{10-2.5}$	No adjustment	1.019 (1.005, 1.033)
	${\text{NO}}_2$	1.020 (0.999, 1.043)
	${\text{SO}}_2$	1.022 (1.007, 1.036)

Note: CI, confidence interval; ${\text{NO}}_2$, nitrogen dioxide; ${\mathrm{PM}}_{2.5}$, particulate matter with aerodynamic diameter $\le 2.5\mathrm{\mu }\mathrm{m}$; ${\mathrm{PM}}_{10}$, particulate matter with aerodynamic diameter $\le 10\mathrm{\mu }\mathrm{m}$; ${\mathrm{PM}}_{10-2.5}$, coarse particulate matter; RR, relative risk; ${\text{SO}}_2$, sulfur dioxide. In single-pollutant models, a subset of data without any missing copollutants was used to ensure comparability.

^aCombined RRs of suicide per interquartile range (IQR) increase in the average 0–1 day concentration across the cities ($14.1\text{ppb}$ for ${\text{NO}}_2$, $4.3\text{ppb}$ for ${\text{SO}}_2$, $36.4{\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$ for ${\mathrm{PM}}_{10}$, $16.9{\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$ for ${\mathrm{PM}}_{2.5}$, and $13.1{\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$ for ${\mathrm{PM}}_{10-2.5}$), after adjusting for potential confounders (i.e., ambient temperature, sunshine duration, day-of-week, public holiday, seasonality, and long-term time trend).