Table 7. The association of individuals’ mental well-being with each of NO₂, PM10, and PM2.5 air pollutants linked at the LSOAs level in bi-pollutant models adjusted for SO₂ pollutant (N = 349,748 surveys from 60,146 individuals).

		Mental well-being (GHQ0-36a ≥ 12)	Mental well-being (GHQ0-12b ≥ 2)	Mental well-being (GHQ0-12b ≥ 4)
		OR [95%CI]	OR [95%CI]	OR [95%CI]
Overall pollution effect
NO2—SO2 Model	NO2 (μg/m3)	1.11 [1.07, 1.14]**	1.13 [1.10, 1.16]**	1.11 [1.08, 1.15]**
	SO2 (μg/m3)	1.18 [1.06, 1.31]**	1.14 [1.02, 1.26]*	1.17 [1.04, 1.31]**
PM10—SO2 Model	PM10 (μg/m3)	1.19 [1.12, 1.27]**	1.25 [1.18, 1.33]**	1.20 [1.12, 1.29]**
	SO2 (μg/m3)	1.24 [1.12, 1.37]**	1.21 [1.09, 1.33]**	1.24 [1.11, 1.39]**
PM2.5—SO2 Model	PM2.5 (μg/m3)	1.31 [1.20, 1.43]**	1.40 [1.29, 1.52]**	1.34 [1.22, 1.47]**
	SO2 (μg/m3)	1.23 [1.11, 1.37]**	1.20 [1.08, 1.33]**	1.23 [1.10, 1.38]**

**P-value <0.01

*P-value<0.05

ORs and 95%CIs are expressed in terms of 10 μg/m³ increase in the air pollutants.

GHQ0-36^a: GHQ scale composed of 12 questions, each scored using a Likert format: 0-1-2-3 and summed up by adding all the items generating a scale ranging from 0 to 36; the 0–36 scale is dichotomised using a cut-off score of 12 based on relevant literature into good mental well-being (score<12) and poor mental well-being (score ≥ 12)

GHQ0-12^b: GHQ scale composed of 12 questions, each scored using a simple binary format: 0-0-1-1 and summed up by adding all the items generating a scale ranging from 0 to 12; the 0–12 scale is dichotomised using two cut-off scores of 2 and 4 based on relevant literature into good mental well-being (score<2 or score<4) and poor mental well-being (score ≥ 2 or score ≥ 4)

Models are additionally adjusted for age, gender, ethnicity, country of birth, marital status, education, occupation, perceived financial situation, smoking status and year dummies (2009–2019).