Table 3.

Subgroup analyses of crude and adjusted odd ratios (95% confidence interval, CI) of meteorological conditions and air pollution parameters (mean of 3 years [1095 days] before index date) for thyroid cancer according to age, sex, income, and region of residence.

Characteristics	Odds ratio for thyroid cancer (95% CI)
	Model 2 †‡	P value
Age < 60 years old (n = 14,985)
Temperature range (°C)	1.12 (1.06–1.19)	< 0.001*
Ambient atmospheric pressure (hPa)	1.03 (1.02–1.04)	< 0.001*
NO2 (0.01 ppm)	1.52 (1.33–1.73)	< 0.001*
O3 (0.01 ppm)	1.46 (1.10–1.94)	0.010*
PM10 (10 µg/m3)	0.66 (0.59–0.73)	< 0.001*
Age ≥ 60 years old (n = 8175)
Ambient atmospheric pressure (hPa)	1.07 (1.01–1.12)	0.012*
NO2 (0.01 ppm)	1.03 (1.02–1.04)	< 0.001*
O3 (0.01 ppm)	1.40 (1.28–1.54)	< 0.001*
PM10 (10 µg/m3)	0.60 (0.54–0.67)	< 0.001*
Males (n = 4965)
Relative humidity (%)	1.05 (1.03–1.08)	< 0.001*
NO2 (0.01 ppm)	1.77 (1.52–2.05)	< 0.001*
PM10 (10 μg/m3)	0.51 (0.43–0.60)	< 0.001*
Females (n = 18,195)
Ambient atmospheric pressure (hPa)	1.03 (1.02–1.04)	< 0.001*
Sunshine duration (hr)	1.15 (1.02–1.30)	0.022*
NO2 (0.01 ppm)	1.22 (1.13–1.31)	< 0.001*
PM10 (10 μg/m3)	0.69 (0.63–0.75)	< 0.001*
Low income (n = 9260)
Ambient atmospheric pressure (hPa)	1.03 (1.02–1.04)	< 0.001*
NO2 (0.01 ppm)	1.18 (1.06–1.31)	0.003*
PM10 (10 μg/m3)	0.66 (0.59–0.75)	< 0.001*
High income (n = 13,900)
Ambient atmospheric pressure (hPa)	1.02 (1.01–1.04)	< 0.001*
NO2 (0.01 ppm)	1.36 (1.25–1.47)	< 0.001*
PM10 (10 μg/m3)	0.64 (0.58–0.70)	< 0.001*
Urban (n = 11,080)
Relative humidity (%)	0.97 (0.96–0.99)	< 0.001*
NO2 (0.01 ppm)	1.27 (1.08–1.50)	0.004*
O3 (0.01 ppm)	2.57 (1.86–3.55)	< 0.001*
CO (ppm)	45.03 (14.26–142.22)	< 0.001*
PM10 (10 μg/m3)	0.53 (0.46–0.61)	< 0.001*
Rural (n = 12,080)
Temperature range (°C)	1.19 (1.08–1.30)	< 0.001*
Relative humidity (%)	1.08 (1.05–1.10)	< 0.001*
NO2 (0.01 ppm)	2.08 (1.76–2.46)	0.016*
O3 (0.01 ppm)	1.58 (1.09–2.29)	< 0.001*
CO (ppm)	0.05 (0.02–0.13)	0.001*
PM10 (10 μg/m3)	0.70 (0.57–0.86)	0.007*

CCI Charlson comorbidity index; DBP diastolic blood pressure; SBP, systolic blood pressure.

*Conditional logistic regression model, significance at P < 0.05.

^†Stratified model for age group, sex, income, and region of residence.

^‡Model 2 was adjusted for total cholesterol, SBP, DBP, fasting blood glucose, obesity, smoking status, alcohol consumption, CCI score, temperature range, relative humidity, ambient atmospheric pressure, sunshine duration, SO₂, NO₂, O₃, CO, and PM₁₀ using the forward selection method.