Table 3

Adjusted HRs for incident dementia during 2005–2013 by air and noise pollutants

ExposureIQR changeHR1* (95% CI)HR2† (95% CI)HR3‡ (95% CI)HR4§ (95% CI)
NO2 +7.47 µg/m3 1.17 (1.06 to 1.28)1.16 (1.05 to 1.28)1.16 (1.05 to 1.27)1.15 (1.04 to 1.28)
PM2.5 +0.95 µg/m3 1.07 (1.02 to 1.12)1.07 (1.02 to 1.12)1.06 (1.02 to 1.12)1.06 (1.01 to 1.13)
PM2.5 (traffic)+0.58 µg/m3 1.09 (1.02 to 1.17)1.08 (1.01 to 1.16)1.08 (1.01 to 1.16)1.08 (0.99 to 1.18)
O3 +5.56 µg/m3 0.84 (0.75 to 0.93)0.84 (0.75 to 0.94)0.85 (0.76 to 0.94)0.85 (0.76 to 0.96)
Lnight +2.68 dB1.02 (1.00 to 1.05)1.02 (1.00 to 1.05)1.02 (1.00 to 1.05)1.01 (0.98 to 1.03)
Distance to major road−310 m1.02 (0.97 to 1.08)1.02 (0.97 to 1.08)1.02 (0.97 to 1.08)1.00 (0.95 to 1.05)
  • *HR1: Cox model with practice fitted as shared frailty. Adjusted for age, sex, ethnicity, smoking and body mass index.

  • †HR2: As HR1, plus additional adjustment for Index of Multiple Deprivation.

  • ‡HR3: As HR2, plus additional adjustment for comorbidity (ischaemic heart disease, stroke, diabetes, heart failure).

  • §HR4: As HR2, plus additional adjustment for Lnight (NO2 and PM2.5 estimates) or NO2 (Lnight and distance estimates).

  • Lnight, night-time noise levels; NO2, nitrogen dioxide; O3, ozone; PM2.5, particulate matter ≤2.5 µm.