Acute Effects of Air Pollution on Hospital Admissions for Asthma, COPD, and Bronchiectasis in Ahvaz, Iran

Figures & data

Table 1 The Number of Hospital Admissions Due to Asthma, COPD, and Bronchiectasis in Population Subgroups and Descriptive Statistics of Air Pollutants and Meteorological Parameters in Ahvaz City, 2008–2018

Variable (Mean per Day)	N	Mean	SD	Min	Max	Q1	Median	Q3
Total people/Asthma	3090	0.8	1.8	0	29	0	0	1
Men/Asthma	1513	0.4	1.2	0	18	0	0	0
Women/Asthma	1577	0.4	1.1	0	18	0	0	0
≤60years/Asthma	2508	0.7	1.7	0	29	0	0	1
>60 years/Asthma	582	0.1	0.5	0	6	0	0	0
Total people/COPD	4534	1.2	1.7	0	12	0	1	2
Men/COPD	3166	0.9	1.4	0	12	0	0	2
Women/COPD	1368	0.4	0.8	0	7	0	0	0
≤60years/COPD	1625	0.3	0.7	0	6	0	0	0
>60 years/COPD	2909	0.8	1.3	0	12	0	0	1
Total people/Bronchiectasis	1994	0.6	1.0	0	8	0	0	1
Men/Bronchiectasis	918	0.3	0.7	0	6	0	0	0
Women/Bronchiectasis	1076	0.3	0.7	0	6	0	0	0
≤60years/Bronchiectasis	987	0.3	0.7	0	6	0	0	0
>60 years/Bronchiectasis	1007	0.3	0.7	0	8	0	0	0
O3 (µg/m^3)	–	70.5	188.6	0.04	6520.0	26.4	42.7	64.6
PM2.5 (µg/m^3)	–	85.7	150.4	0.57	3938	35.9	52.7	81.2
PM10 (µg/m^3)	–	216.9	278.3	1.8	4324.2	105.8	149.2	222.4
NO2 (µg/m^3)	–	46.4	43.1	1.5	443.8	17.8	35.6	60.7
NO ((µg/m^3))	–	29.1	31.0	0.12	608.7	9.1	19.6	38.2
CO (µg/m^3)	–	1.5	2.1	0.1	70.4	0.6	1.13	2.0
SO2 (µg/m^3)	–	48.8	57.0	0.0	907.4	19.3	35.9	59.3
Temperature (° C)	–	27.0	9.4	1.4	47.8	18.4	27.7	36.0
Relative Humidity (%)	–	42.3	17.9	7.0	96.0	27.5	40.0	54.5

Table 2 Correlation Coefficients Between Air Pollutants and Meteorological Parameters in Ahvaz, Between 2008 and 2018

Variable	O3	NO	NO2	SO2	CO	PM10	PM25	Temperature	Relative Humidity
O3	1
NO	−0.03	1
NO2	0.01	0.69*	1
SO2	0.25*	−0.01	−0.13*	1
CO	−0.23*	0.37*	0.29*	−0.26*	1
PM10	−0.03	−0.20*	−0.22*	0.20*	−0.13*	1
PM25	−0.11*	−0.16*	−0.18*	0.11*	0.02	0.75*	1
Temperature	0.04*	−0.22*	−0.10*	0.01	−0.04	0.27*	0.25*	1
Relative humidity	−0.03	0.32*	0.24*	−0.02	0.09*	−0.29*	−0.26*	−0.74*	1

Note: *Statistically significant (P-value<0.05).

Table 3 The Relative Risk (95% CIs) of Asthma Admissions with an Increase of 10 µg/M³ in PM_2.5, NO, NO₂ and SO₂ According to Single Lag, Adjusted Unconstrained and Constrained DLM Models^a

Respondents	Pollutant	Lag	Lag Terms Model One at Time RR (95% CI)	Adjusted Unconstrained DLM RR (95% CI)	Adjusted Constrained DLM RR(95% CI)
Total	PM2.5	0	1.002 (1.000–1.004)	1.000 (0.997–1.003)	1.001 (0.998–1.003)
		1	1.000 (0.997–1.003)	0.998 (0.995–1.002)	1.002 (1.000–1.004)
		2	1.004 (1.002–1.006)	1.004 (1.002–1.007)*	1.002 (1.000–1.004)
		3	1.002 (0.999–1.004)	1.003 (1.000–1.006)	1.000 (0.999–1.001)
		4	1.000 (0.997–1.003)	0.997 (0.994–1.001)	1.000 (0.999–1.001)
		5	1.000 (0.997–1.003)	0.999 (0.996–1.002)	1.000 (0.999–1.001)
		6	1.002 (0.999–1.004)	1.003 (1.000–1.006)	1.000 (0.999–1.001)
		7	1.000 (0.997–1.003)	0.998 (0.995–1.002)	1.000 (0.999–1.001)
	NO	0	0.999 (0.998–1.001)	0.984 (0.966–1.003)	0.993 (0.975–1.010)
		1	1.000 (0.999–1.002)	1.025 (1.005–1.045)*	1.000 (0.989–1.010)
		2	0.999 (0.997–1.001)	0.973 (0.952–0.994)	1.000 (0.989–1.010)
		3	1.001 (0.999–1.002)	1.009 (0.989–1.030)	1.003 (0.997–1.009)
		4	1.001 (1.000–1.003)	1.016 (0.997–1.035)	1.003 (0.997–1.009)
		5	1.000 (0.998–1.002)	0.988 (0.968–1.008)	1.003 (0.997–1.009)
		6	1.001 (0.999–1.002)	1.014 (0.994–1.034)	1.003 (0.997–1.009)
		7	1.000 (0.998–1.002)	0.992 (0.974–1.010)	1.003 (0.997–1.009)
	NO2	0	0.994 (0.971–1.016)	0.981 (0.953–1.009)	0.995 (0.970–1.022)
		1	1.000 (0.978–1.022)	1.040 (1.008–1.074)*	0.996 (0.981–1.011)
		2	0.975 (0.953–0.999)	0.940 (0.908–0.973)	0.996 (0.981–1.011)
		3	1.008 (0.987–1.030)	1.033 (1.001–1.067)*	1.000 (0.993–1.006)
		4	1.010 (0.988–1.031)	1.025 (0.993–1.057)	1.000 (0.993–1.006)
		5	0.981 (0.959–1.004)	0.955 (0.923–0.988)	1.000 (0.993–1.006)
		6	0.997 (0.975–1.019)	1.008 (0.975–1.042)	1.000 (0.993–1.006)
		7	1.002 (0.981–1.024)	1.002 (0.976–1.030)	1.000 (0.993–1.006)
Male	PM2.5	0	1.003 (1.000–1.006)	1.002 (0.999–1.006)	1.002 (0.999–1.006)
		1	1.001 (0.998–1.004)	1.000 (0.996–1.004)	1.002 (0.999–1.004)
		2	1.004 (1.001–1.006)	1.004 (1.000–1.007)	1.002 (0.999–1.004)
		3	1.002 (0.998–1.005)	1.002 (0.998–1.006)	1.000 (0.999–1.001)
		4	0.997 (0.993–1.002)	0.993 (0.987–0.999)	1.000 (0.999–1.001)
		5	1.002 (0.999–1.005)	1.001 (0.997–1.006)	1.000 (0.999–1.001)
		6	1.004 (1.001–1.007)	1.004 (1.001–1.008)*	1.000 (0.999–1.001)
		7	1.000 (0.996–1.004)	0.997 (0.992–1.002)	1.000 (0.999–1.001)
	NO2	0	1.010 (0.979–1.041)	0.985 (0.947–1.024)	1.000 (0.965–1.037)
		1	1.024 (0.995–1.054)	1.052 (1.007–1.099)*	1.007 (0.987–1.028)
		2	0.998 (0.968–1.030)	0.949 (0.904–0.996)	1.007 (0.987–1.028)
		3	1.021 (0.992–1.051)	1.045 (0.999–1.093)	1.002 (0.993–1.011)
		4	1.013 (0.984–1.044)	1.014 (0.968–1.062)	1.002 (0.993–1.011)
		5	0.983 (0.952–1.016)	0.960 (0.914–1.008)	1.002 (0.993–1.011)
		6	1.005 (0.974–1.036)	1.018 (0.970–1.068)	1.002 (0.993–1.011)
		7	1.004 (0.973–1.036)	0.998 (0.959–1.039)	1.002 (0.993–1.011)
Female	PM2.5	0	1.000 (0.996–1.004)	0.997 (0.993–1.002)	0.998 (0.994–1.002)
		1	0.996 (0.991–1.002)	0.994 (0.988–1.000)	1.002 (1.000–1.005)
		2	1.004 (1.001–1.006)	1.006 (1.002–1.010)*	1.002 (1.000–1.005)
		3	1.002 (0.999–1.005)	1.004 (0.999–1.008)	1.000 (0.998–1.001)
		4	1.002 (0.998–1.005)	1.002 (0.998–1.007)	1.000 (0.998–1.001)
		5	0.994 (0.988–1.000)	0.993 (0.986–1.000)	1.000 (0.998–1.001)
		6	0.998 (0.993–1.003)	0.999 (0.993–1.004)	1.000 (0.998–1.001)
		7	1.001 (0.997–1.004)	1.000 (0.996–1.005)	1.000 (0.998–1.001)
	NO	0	0.998 (0.996–1.001)	0.969 (0.944–0.994)	0.983 (0.960–1.007)
		1	1.000 (0.998–1.002)	1.041 (1.016–1.067)*	0.999 (0.986–1.013)
		2	0.998 (0.995–1.000)	0.954 (0.927–0.982)	0.999 (0.986–1.013)
		3	1.001 (0.999–1.003)	1.020 (0.994–1.046)	1.003 (0.996–1.010)
		4	1.001 (0.999–1.003)	1.006 (0.982–1.032)	1.003 (0.996–1.010)
		5	1.001 (0.999–1.003)	0.995 (0.969–1.021)	1.003 (0.996–1.010)
		6	1.001 (0.999–1.003)	1.008 (0.983–1.033)	1.003 (0.996–1.010)
		7	1.000 (0.998–1.002)	0.998 (0.975–1.021)	1.003 (0.996–1.010)
≤60 years	PM2.5	0	1.000 (0.997–1.003)	0.999 (0.995–1.002)	0.999 (0.995–1.002)
		1	1.000 (0.996–1.003)	0.999 (0.995–1.003)	1.002 (1.000–1.004)
		2	1.003 (1.001–1.005)	1.005 (1.001–1.008)*	1.002 (1.000–1.004)
		3	1.002 (0.999–1.005)	1.004 (1.000–1.007)	1.000 (0.999–1.001)
		4	0.999 (0.995–1.003)	0.996 (0.992–1.000)	1.000 (0.999–1.001)
		5	1.000 (0.997–1.003)	0.998 (0.995–1.002)	1.000 (0.999–1.001)
		6	1.002 (0.999–1.005)	1.003 (0.999–1.006)	1.000 (0.999–1.001)
		7	1.001 (0.998–1.004)	1.000 (0.996–1.003)	1.000 (0.999–1.001)
	NO2	0	0.993 (0.968–1.019)	0.981 (0.950–1.013)	0.997 (0.968–1.027)
		1	0.996 (0.971–1.022)	1.042 (1.005–1.081)*	0.993 (0.976–1.011)
		2	0.971 (0.945–0.997)	0.929 (0.893–0.967)	0.993 (0.976–1.011)
		3	1.010 (0.986–1.035)	1.046 (1.009–1.084)	0.999 (0.992–1.007)
		4	1.008 (0.984–1.033)	1.017 (0.981–1.054)	0.999 (0.992–1.007)
		5	0.977 (0.951–1.003)	0.958 (0.922–0.996)	0.999 (0.992–1.007)
		6	0.990 (0.965–1.016)	1.000 (0.963–1.038)	0.999 (0.992–1.007)
		7	0.997 (0.973–1.022)	1.005 (0.975–1.037)	0.999 (0.992–1.007)
>60 years	PM2.5	0	1.006 (1.003–1.009)	1.005 (1.001–1.009)*	1.006 (1.002–1.009)
		1	0.999 (0.993–1.005)	0.993 (0.983–1.002)	1.000 (0.997–1.004)
		2	1.005 (1.002–1.009)	1.003 (0.998–1.008)	1.000 (0.997–1.004)
		3	1.001 (0.996–1.006)	1.001 (0.994–1.009)	1.000 (0.998–1.002)
		4	1.001 (0.996–1.006)	1.001 (0.994–1.007)	1.000 (0.998–1.002)
		5	0.998 (0.992–1.005)	1.000 (0.993–1.008)	1.000 (0.998–1.002)
		6	0.999 (0.993–1.005)	1.002 (0.996–1.009)	1.000 (0.998–1.002)
		7	0.992 (0.982–1.002)	0.990 (0.980–1.001)	1.000 (0.998–1.002)
	NO	0	0.998 (0.995–1.002)	0.959 (0.919–1.000)	0.979 (0.942–1.018)
		1	1.002 (0.999–1.005)	1.065 (1.026–1.106)*	1.012 (0.993–1.031)
		2	1.000 (0.996–1.003)	0.946 (0.904–0.990)	1.012 (0.993–1.031)
		3	1.004 (1.002–1.007)	1.057 (1.019–1.095)*	1.010 (1.000–1.021)
		4	1.002 (0.999–1.005)	1.015 (0.976–1.055)	1.010 (1.000–1.021)
		5	1.000 (0.997–1.004)	0.974 (0.931–1.018)	1.010 (1.000–1.021)
		6	1.001 (0.998–1.005)	1.020 (0.978–1.064)	1.010 (1.000–1.021)
		7	1.002 (0.999–1.005)	1.009 (0.974–1.046)	1.010 (1.000–1.021)
	NO2	0	1.006 (0.965–1.049)	0.982 (0.931–1.037)	0.996 (0.949–1.045)
		1	1.019 (0.978–1.060)	1.042 (0.980–1.108)	1.005 (0.978–1.033)
		2	0.996 (0.953–1.040)	0.974 (0.913–1.040)	1.005 (0.978–1.033)
		3	1.006 (0.964–1.049)	0.986 (0.924–1.053)	1.005 (0.993–1.016)
		4	1.026 (0.988–1.067)	1.069 (1.004–1.137)*	1.005 (0.993–1.016)
		5	1.001 (0.959–1.044)	0.950 (0.891–1.012)	1.005 (0.993–1.016)
		6	1.019 (0.980–1.061)	1.015 (0.952–1.081)	1.005 (0.993–1.016)
		7	1.029 (0.992–1.068)	1.009 (0.959–1.062)	1.005 (0.993–1.016)
	SO2	0	1.012 (0.972–1.054)	0.993 (0.936–1.053)	0.986 (0.937–1.038)
		1	1.028 (0.992–1.066)	1.005 (0.942–1.072)	1.031 (1.006–1.057)
		2	1.049 (1.014–1.085)	1.069 (1.017–1.124)*	1.031 (1.006–1.057)
		3	1.010 (0.969–1.053)	0.986 (0.924–1.052)	1.003 (0.990–1.016)
		4	1.000 (0.956–1.045)	0.958 (0.887–1.035)	1.003 (0.990–1.016)
		5	1.028 (0.991–1.066)	1.040 (0.978–1.106)	1.003 (0.990–1.016)
		6	1.032 (0.997–1.069)	1.026 (0.968–1.088)	1.003 (0.990–1.016)
		7	1.012 (0.971–1.054)	0.985 (0.931–1.041)	1.003 (0.990–1.016)

Notes: *Statistically significant. ^aAdjusted for trend, seasonality, temperature, relative humidity, weekdays, and holidays.

Table 4 The Relative Risk (95% CIs) of COPD Admissions with an Increase of 10 µg/M³ in PM_2.5, NO, NO₂, and CO According to Single Lag, Adjusted Unconstrained and Constrained DLM Models^a

Respondents	Pollutant	Lag	Lag Terms Model One at Time RR (95% CI)	Adjusted Unconstrained DLM RR (95% CI)	Adjusted Constrained DLM RR(95% CI)
Total	PM2.5	0	0.999 (0.997–1.001)	0.999 (0.996–1.001)	0.998 (0.996–1.001)
		1	1.000 (0.998–1.002)	1.000 (0.997–1.002)	1.001 (1.000–1.003)
		2	1.001 (0.999–1.003)	1.003 (1.001–1.005)*	1.001 (1.000–1.003)
		3	1.001 (0.998–1.003)	1.001 (0.999–1.003)	1.000 (0.999–1.001)
		4	0.999 (0.996–1.001)	0.997 (0.994–1.000)	1.000 (0.999–1.001)
		5	1.000 (0.997–1.002)	1.000 (0.997–1.003)	1.000 (0.999–1.001)
		6	1.000 (0.998–1.003)	1.001 (0.998–1.004)	1.000 (0.999–1.001)
		7	1.000 (0.998–1.002)	0.999 (0.997–1.002)	1.000 (0.999–1.001)
	NO	0	1.000 (0.999–1.001)	0.994 (0.980–1.008)	1.001 (0.989–1.014)
		1	1.001 (1.000–1.002)	1.021 (1.006–1.036)*	0.999 (0.992–1.007)
		2	0.999 (0.998–1.000)	0.974 (0.957–0.991)	0.999 (0.992–1.007)
		3	1.000 (0.999–1.002)	1.017 (1.001–1.032)*	1.000 (0.996–1.004)
		4	1.000 (0.999–1.001)	0.993 (0.977–1.009)	1.000 (0.996–1.004)
		5	1.000 (0.998–1.001)	0.992 (0.976–1.009)	1.000 (0.996–1.004)
		6	1.000 (0.999–1.002)	1.006 (0.992–1.022)	1.000 (0.996–1.004)
		7	1.001 (0.999–1.002)	1.001 (0.987–1.014)	1.000 (0.996–1.004)
Male	PM2.5	0	0.999 (0.997–1.002)	0.999 (0.995–1.002)	0.998 (0.995–1.002)
		1	1.000 (0.997–1.002)	0.999 (0.996–1.002)	1.001 (0.999–1.003)
		2	1.002 (0.999–1.004)	1.003 (1.000–1.006)*	1.001 (0.999–1.003)
		3	1.001 (0.998–1.003)	1.001 (0.998–1.004)	1.000 (0.999–1.001)
		4	0.999 (0.997–1.002)	0.998 (0.995–1.001)	1.000 (0.999–1.001)
		5	1.000 (0.998–1.003)	1.001 (0.998–1.004)	1.000 (0.999–1.001)
		6	1.000 (0.998–1.003)	1.001 (0.998–1.004)	1.000 (0.999–1.001)
		7	1.000 (0.997–1.003)	0.999 (0.996–1.002)	1.000 (0.999–1.001)
	NO	0	1.000 (0.999–1.002)	0.994 (0.978–1.011)	1.001 (0.986–1.017)
		1	1.001 (0.999–1.002)	1.020 (1.002–1.039)*	0.998 (0.989–1.008)
		2	0.999 (0.997–1.000)	0.974 (0.954–0.995)	0.998 (0.989–1.008)
		3	1.000 (0.998–1.001)	1.011 (0.991–1.030)	0.998 (0.993–1.003)
		4	0.999 (0.998–1.001)	0.993 (0.974–1.012)	0.998 (0.993–1.003)
		5	0.999 (0.998–1.001)	0.988 (0.968–1.008)	0.998 (0.993–1.003)
		6	1.000 (0.999–1.002)	1.008 (0.990–1.026)	0.998 (0.993–1.003)
		7	1.001 (0.999–1.002)	1.000 (0.984–1.016)	0.998 (0.993–1.003)
Female	NO	0	1.000 (0.998–1.003)	0.995 (0.971–1.019)	1.002 (0.980–1.025)
		1	1.001 (0.999–1.003)	1.021 (0.995–1.047)	1.001 (0.988–1.014)
		2	1.000 (0.997–1.002)	0.973 (0.945–1.003)	1.001 (0.988–1.014)
		3	1.001 (1.000–1.003)	1.028 (1.002–1.055)*	1.003 (0.996–1.009)
		4	1.000 (0.998–1.002)	0.993 (0.966–1.020)	1.003 (0.996–1.009)
		5	1.000 (0.998–1.002)	0.998 (0.969–1.027)	1.003 (0.996–1.009)
		6	1.000 (0.998–1.002)	1.004 (0.978–1.032)	1.003 (0.996–1.009)
		7	1.001 (0.999–1.003)	1.001 (0.977–1.026)	1.003 (0.996–1.009)
	NO2	0	1.021 (0.997–1.046)	1.008 (0.975–1.041)	1.013 (0.983–1.044)
		1	1.023 (0.999–1.047)	1.021 (0.981–1.061)	1.004 (0.987–1.022)
		2	1.007 (0.982–1.032)	0.998 (0.958–1.040)	1.004 (0.987–1.022)
		3	1.007 (0.982–1.033)	0.972 (0.933–1.014)	1.005 (0.998–1.012)
		4	1.026 (1.003–1.050)	1.049 (1.010–1.090)*	1.005 (0.998–1.012)
		5	1.012 (0.987–1.037)	0.986 (0.947–1.027)	1.005 (0.998–1.012)
		6	1.011 (0.986–1.036)	1.009 (0.969–1.051)	1.005 (0.998–1.012)
		7	1.011 (0.987–1.037)	1.001 (0.967–1.035)	1.005 (0.998–1.012)
	CO	0	1.466 (1.180–1.822)	1.643 (1.233–2.191)*	1.654 (1.258–2.174)
		1	1.072 (0.740–1.551)	0.795 (0.501–1.259)	0.772 (0.538–1.108)
		2	0.759 (0.396–1.455)	0.744 (0.355–1.561)	0.772 (0.538–1.108)
		3	0.947 (0.593–1.515)	1.079 (0.622–1.871)	1.055 (0.910–1.222)
		4	0.861 (0.503–1.473)	0.870 (0.463–1.635)	1.055 (0.910–1.222)
		5	1.038 (0.697–1.544)	1.051 (0.667–1.658)	1.055 (0.910–1.222)
		6	1.149 (0.831–1.590)	1.203 (0.781–1.852)	1.055 (0.910–1.222)
		7	1.061 (0.732–1.539)	1.042 (0.660–1.645)	1.055 (0.910–1.222)
≤60 years	PM2.5	0	0.997 (0.992–1.002)	0.997 (0.991–1.002)	0.996 (0.991–1.001)
		1	0.998 (0.993–1.003)	0.998 (0.993–1.003)	1.001 (0.998–1.004)
		2	1.001 (0.998–1.005)	1.004 (1.000–1.009)*	1.001 (0.998–1.004)
		3	1.000 (0.996–1.004)	1.001 (0.996–1.006)	0.999 (0.998–1.001)
		4	0.996 (0.991–1.001)	0.995 (0.990–1.001)	0.999 (0.998–1.001)
		5	0.997 (0.992–1.002)	0.999 (0.994–1.004)	0.999 (0.998–1.001)
		6	1.000 (0.996–1.004)	1.001 (0.996–1.005)	0.999 (0.998–1.001)
		7	1.000 (0.996–1.004)	0.999 (0.995–1.004)	0.999 (0.998–1.001)
>60 years	NO	0	1.001 (0.999–1.002)	0.999 (0.983–1.016)	1.007 (0.992–1.023)
		1	1.001 (1.000–1.003)	1.022 (1.004–1.040)*	1.000 (0.991–1.009)
		2	0.999 (0.998–1.001)	0.972 (0.951–0.993)	1.000 (0.991–1.009)
		3	1.001 (1.000–1.003)	1.020 (1.002–1.039)*	1.003 (0.998–1.008)
		4	1.001 (1.000–1.002)	1.000 (0.983–1.019)	1.003 (0.998–1.008)
		5	1.001 (0.999–1.002)	1.005 (0.986–1.025)	1.003 (0.998–1.008)
		6	1.000 (0.998–1.001)	0.994 (0.975–1.014)	1.003 (0.998–1.008)
		7	1.000 (0.999–1.002)	1.006 (0.989–1.023)	1.003 (0.998–1.008)

Notes: *Statistically significant. ^aAdjusted for trend, seasonality, temperature, relative humidity, weekdays, and holidays.

Table 5 The Relative Risk (95% CIs) of Bronchiectasis Admissions with an Increase of 10 µg/M³ in PM₁₀, so, and CO According to Single Lag, Adjusted Unconstrained and Constrained DLM Models^a

Respondents	Pollutant	Lag	Lag Terms Model One at Time RR (95% CI)	Adjusted Unconstrained DLM RR (95% CI)	Adjusted Constrained DLM RR(95% CI)
Total	SO2	0	0.996 (0.976–1.016)	0.983 (0.956–1.010)	0.992 (0.967–1.017)
		1	1.009 (0.992–1.027)	1.030 (1.005–1.056)*	1.006 (0.993–1.020)
		2	1.000 (0.981–1.019)	0.991 (0.963–1.020)	1.006 (0.993–1.020)
		3	0.999 (0.980–1.019)	0.984 (0.954–1.014)	1.002 (0.996–1.007)
		4	1.013 (0.996–1.030)	1.027 (1.002–1.052)*	1.002 (0.996–1.007)
		5	1.007 (0.988–1.025)	0.997 (0.970–1.026)	1.002 (0.996–1.007)
		6	1.002 (0.983–1.021)	1.002 (0.975–1.030)	1.002 (0.996–1.007)
		7	0.997 (0.978–1.017)	0.995 (0.970–1.020)	1.002 (0.996–1.007)
	CO	0	1.132 (0.842–1.523)	1.262 (0.885–1.800)	1.262 (0.909–1.751)
		1	0.972 (0.656–1.441)	0.977 (0.613–1.557)	0.913 (0.688–1.213)
		2	0.878 (0.556–1.385)	0.965 (0.594–1.568)	0.913 (0.688–1.213)
		3	0.889 (0.567–1.394)	0.746 (0.484–1.148)	1.020 (0.909–1.145)
		4	1.255 (0.994–1.584)	1.542 (1.035–2.298)*	1.020 (0.909–1.145)
		5	1.023 (0.724–1.443)	0.792 (0.462–1.357)	1.020 (0.909–1.145)
		6	0.638 (0.338–1.203)	0.618 (0.311–1.230)	1.020 (0.909–1.145)
		7	1.088 (0.807–1.467)	1.242 (0.931–1.657)	1.020 (0.909–1.145)
Male	PM10	0	1.002 (0.999–1.004)	1.002 (0.999–1.005)	1.001 (0.998–1.004)
		1	1.000 (0.997–1.003)	0.999 (0.995–1.002)	1.001 (0.999–1.003)
		2	1.003 (1.000–1.005)	1.003 (1.001–1.006)*	1.001 (0.999–1.003)
		3	0.997 (0.992–1.001)	0.996 (0.991–1.001)	0.998 (0.997–1.000)
		4	0.997 (0.993–1.001)	0.998 (0.994–1.002)	0.998 (0.997–1.000)
		5	0.999 (0.996–1.003)	1.001 (0.997–1.004)	0.998 (0.997–1.000)
		6	0.998 (0.994–1.002)	0.999 (0.995–1.003)	0.998 (0.997–1.000)
		7	0.996 (0.991–1.000)	0.997 (0.992–1.002)	0.998 (0.997–1.000)
	SO2	0	0.990 (0.960–1.021)	0.958 (0.919–1.000)	0.978 (0.941–1.016)
		1	1.019 (0.995–1.043)	1.054 (1.021–1.088)*	1.014 (0.995–1.032)
		2	0.999 (0.971–1.028)	0.990 (0.951–1.031)	1.014 (0.995–1.032)
		3	0.985 (0.954–1.017)	0.976 (0.929–1.026)	1.000 (0.991–1.008)
		4	0.998 (0.969–1.027)	1.002 (0.959–1.046)	1.000 (0.991–1.008)
		5	1.009 (0.983–1.036)	1.009 (0.969–1.050)	1.000 (0.991–1.008)
		6	1.015 (0.990–1.040)	1.026 (0.993–1.061)	1.000 (0.991–1.008)
		7	0.995 (0.966–1.024)	0.982 (0.947–1.018)	1.000 (0.991–1.008)
Female	PM10	0	1.000 (0.997–1.003)	0.999 (0.996–1.003)	1.000 (0.996–1.003)
		1	1.002 (0.999–1.004)	1.002 (0.999–1.005)	1.001 (0.999–1.003)
		2	1.000 (0.996–1.003)	0.999 (0.996–1.003)	1.001 (0.999–1.003)
		3	0.999 (0.996–1.003)	0.999 (0.995–1.003)	1.000 (0.999–1.001)
		4	1.001 (0.998–1.004)	1.002 (0.999–1.005)	1.000 (0.999–1.001)
		5	0.998 (0.995–1.002)	0.996 (0.991–1.000)	1.000 (0.999–1.001)
		6	1.002 (0.999–1.004)	1.003 (1.000–1.006)*	1.000 (0.999–1.001)
		7	1.000 (0.997–1.003)	1.000 (0.997–1.003)	1.000 (0.999–1.001)
	SO2	0	1.001 (0.975–1.027)	1.008 (0.974–1.044)	1.009 (0.977–1.042)
		1	1.002 (0.976–1.028)	1.005 (0.965–1.046)	0.999 (0.980–1.018)
		2	1.001 (0.975–1.027)	0.992 (0.950–1.035)	0.999 (0.980–1.018)
		3	1.009 (0.985–1.034)	0.991 (0.951–1.032)	1.003 (0.996–1.011)
		4	1.024 (1.002–1.046)	1.044 (1.013–1.076)*	1.003 (0.996–1.011)
		5	1.005 (0.979–1.031)	0.994 (0.958–1.032)	1.003 (0.996–1.011)
		6	0.990 (0.962–1.018)	0.970 (0.927–1.016)	1.003 (0.996–1.011)
		7	1.001 (0.975–1.027)	1.014 (0.979–1.051)	1.003 (0.996–1.011)
	CO	0	1.203 (0.881–1.641)	1.449 (1.007–2.086)*	1.375 (0.975–1.940)
		1	0.961 (0.593–1.555)	0.853 (0.495–1.471)	0.907 (0.652–1.261)
		2	0.987 (0.626–1.558)	1.214 (0.692–2.131)	0.907 (0.652–1.261)
		3	0.674 (0.309–1.472)	0.510 (0.211–1.230)	1.044 (0.913–1.195)
		4	1.295 (1.001–1.676)	1.822 (1.075–3.090)*	1.044 (0.913–1.195)
		5	1.096 (0.763–1.572)	0.683 (0.336–1.389)	1.044 (0.913–1.195)
		6	0.660 (0.301–1.446)	0.715 (0.318–1.609)	1.044 (0.913–1.195)
		7	1.167 (0.859–1.587)	1.222 (0.889–1.680)	1.044 (0.913–1.195)
>60 years	SO2	0	1.007 (0.985–1.030)	0.989 (0.957–1.023)	1.003 (0.974–1.033)
		1	1.025 (1.006–1.046)	1.043 (1.015–1.071)*	1.012 (0.997–1.027)
		2	1.004 (0.981–1.028)	0.990 (0.958–1.024)	1.012 (0.997–1.027)
		3	0.998 (0.974–1.024)	0.980 (0.942–1.020)	1.000 (0.992–1.007)
		4	1.009 (0.987–1.032)	1.022 (0.989–1.057)	1.000 (0.992–1.007)
		5	1.007 (0.984–1.031)	1.004 (0.969–1.039)	1.000 (0.992–1.007)
		6	0.999 (0.974–1.024)	1.004 (0.970–1.039)	1.000 (0.992–1.007)
		7	0.990 (0.965–1.016)	0.987 (0.954–1.020)	1.000 (0.992–1.007)
	CO	0	1.197 (0.848–1.689)	1.419 (0.948–2.124)	1.405 (0.966–2.043)
		1	1.057 (0.677–1.651)	1.003 (0.599–1.680)	0.937 (0.669–1.314)
		2	0.933 (0.541–1.607)	1.035 (0.568–1.887)	0.937 (0.669–1.314)
		3	0.609 (0.248–1.496)	0.499 (0.201–1.238)	0.948 (0.780–1.153)
		4	1.222 (0.883–1.691)	2.005 (1.126–3.568)*	0.948 (0.780–1.153)
		5	0.813 (0.421–1.570)	0.567 (0.245–1.313)	0.948 (0.780–1.153)
		6	0.337 (0.110–1.037)	0.460 (0.140–1.504)	0.948 (0.780–1.153)
		7	0.912 (0.533–1.561)	1.096 (0.693–1.733)	0.948 (0.780–1.153)

Notes: *Statistically significant. ^aAdjusted for trend, seasonality, temperature, relative humidity, weekdays, and holidays.

Figure 1 The average daily concentration of O₃, NO₂, NO, CO, SO₂, PM₁₀ and PM_2.5 during the study period.