Table 4 Percentage increase of stroke risk associated with per 10 μg/m³ and per IQR increase of SO₂ under single and two-pollutant models

All age

SO₂

Single pollutant

1.27 (0.42–2.12)

2.75 (0.90–4.63)

1.55 (0.02–3.11)

3.38 (0.04–6.82)

SO₂ + NO₂

1.34 (0.31–2.37)

2.90 (0.66–5.20)

1.25 (− 0.48 - 3.01)

2.72 (− 1.04 - 6.62)

SO₂ + PM₁₀

1.21 (0.18–2.26)

2.64 (0.39–4.94)

0.89 (− 0.89 - 2.7)

1.93 (− 1.91 - 5.91)

SO₂ + PM_2.5

2.25 (0.06–4.48)

4.91 (0.12–9.93)

2.71 (− 1.39 - 6.98)

5.94 (− 2.98 - 15.68)

SO₂ + O₃

2.68 (0.75–4.65)

5.88 (1.63–10.3)

4.32 (0.63–8.15)

9.56 (1.36–18.43)

< 65 years

SO₂

Single pollutant

1.39 (0.35–2.45)

3.03 (0.75–5.36)

1.47 (− 0.18 - 3.16)

3.21 (− 0.39 - 6.93)

SO₂ + NO₂

1.59 (0.36–2.83)

3.46 (0.78–6.21)

1.07 (− 0.8 - 2.97)

2.32 (− 1.71 - 6.51)

SO₂ + PM₁₀

1.22 (− 0.02 - 2.47)

2.64 (− 0.04 - 5.40)

1.37 (− 0.55 - 3.33)

2.98 (− 1.18 - 7.32)

SO₂ + PM_2.5

2.23 (− 0.39 - 4.93)

4.88 (− 0.85 - 10.94)

3.94 (− 0.58 - 8.68)

8.71 (− 1.25 - 19.67)

SO₂ + O₃

3.70 (1.36–6.09)

8.15 (2.95–13.60)

4.45 (0.38–8.69)

9.85 (0.82–19.69)

≥65 years

SO₂

Single pollutant

1.21 (0.02–2.42)

2.64 (0.05–5.30)

0.25 (− 2.79 - 3.40)

0.55 (− 5.93 - 7.48)

SO₂ + NO₂

1.09 (− 0.32 - 2.51)

2.36 (− 0.69 - 5.51)

0.67 (− 2.79 - 4.26)

1.45 (− 5.93 - 9.42)

SO₂ + PM₁₀

1.19 (− 0.23 - 2.63)

2.58 (− 0.5 - 5.75)

− 1.21 (− 4.71 - 2.41)

−2.6 (− 9.89 - 5.28)

SO₂ + PM_2.5

2.19 (− 0.49 - 4.94)

4.78 (− 1.06 - 10.96)

− 0.96 (− 8.36 - 7.03)

− 2.06 (− 17.17 - 15.8)

SO₂ + O₃

1.90 (− 0.45 - 4.31)

4.14 (− 0.98 - 9.52)

1.62 (− 5.14 - 8.85)

3.52 (− 10.76 - 20.08)