A meta-analysis, combining Government Office Region-specific relative risk estimates* by ‘super region’ (North, Midlands, South)†
| Disease | Pollutant‡ (UDLM 0–2) | Estimated percentage change in risk (95% CI) per 10 µg/m3 increase in pollutant‡ | Test of heterogeneity between | ||||
|---|---|---|---|---|---|---|---|
| North | Midlands | South | Overall | ‘Super regions’ p Value | Regions p Value | ||
| All MI | O3 | 0.05 (−0.33 to 0.44) | −0.29 (−0.79 to 0.21) | −0.04 (−0.40 to 0.32) | −0.06 (−0.29 to 0.17) | 0.552 | 0.291 |
| NO2 | −0.17 (−0.50 to 0.16) | 0.25 (−0.21 to 0.71) | 0.21 (−0.09 to 0.51) | 0.08 (−0.12 to 0.28) | 0.185 | 0.596 | |
| PM2.5 | −0.51 (−1.24 to 0.22) | 0.47 (−0.42 to 1.36) | 0.01 (−0.61 to 0.63) | −0.06 (−0.48 to 0.36) | 0.236 | 0.429 | |
| PM10 | −0.47 (−1.05 to 0.12) | 0.14 (−0.56 to 0.85) | −0.18 (−0.67 to 0.31) | −0.20 (−0.53 to 0.13) | 0.424 | 0.747 | |
| STEMI | O3 | −0.16 (−0.85 to 0.54) | −0.36 (−1.17 to 0.47) | −0.02 (−0.66 to 0.62) | −0.15 (−0.56 to 0.26) | 0.822 | 0.961 |
| NO2 | −0.21 (−0.81 to 0.39) | −0.07 (−0.82 to 0.68) | −0.35 (−0.88 to 0.19) | −0.24 (−0.59 to 0.11) | 0.838 | 0.994 | |
| PM2.5 | −1.08 (−2.39 to 0.24) | −0.07 (−1.53 to 1.41) | −0.17 (−1.27 to 0.95) | −0.42 (−1.16 to 0.31) | 0.500 | 0.629 | |
| PM10 | −1.05 (−2.10 to 0.01) | −0.19 (−1.34 to 0.97) | 0.01 (−0.88 to 0.89) | −0.36 (−0.95 to 0.22) | 0.308 | 0.102 | |
| NSTEMI | O3 | 0.27 (−0.26 to 0.80) | −0.22 (−0.92 to 0.49) | −0.27 (−0.78 to 0.23) | −0.06 (−0.38 to 0.26) | 0.307 | 0.006 |
| NO2 | −0.20 (−0.67 to 0.26) | 0.79 (0.13 to 1.45) | 0.51 (0.09 to 0.94) | 0.30 (0.01 to 0.58) | 0.022 | 0.353 | |
| PM2.5 | −0.36 (−1.38 to 0.66) | 0.68 (−0.58 to 1.95) | −0.42 (−1.29 to 0.45) | −0.16 (−0.75 to 0.42) | 0.332 | 0.826 | |
| PM10 | −0.22 (−1.03 to 0.60) | 0.38 (−0.62 to 1.39) | −0.79 (−1.48 to −0.11) | −0.36 (−0.82 to 0.11) | 0.155 | 0.786 | |
*Adjusted for a sine/cosine annual cycle, the weekly RCGP influenza-like illness consultation rates per 100 000 England and Wales population, region-specific natural cubic splines for temperature (mean lag 0–1 and mean lag 2–6) and public holidays. Relative risk estimates for NO2, PM2.5 and PM10 additionally adjusted for O3 (UDLM 0–2).
†‘Super regions’ were defined here by grouping three Government Office Regions to form the North (ie, North East; North West; Yorkshire and Humberside); three to form the Midlands (ie, West Midlands; East Midlands; Wales); and four to form the South (ie, South West; East; South East; London).
‡Pollutant metrics: daily mean PM2.5, daily mean PM10, daily maximum 1-hour NO2, daily maximum 8-hour mean O3.
MI, myocardial infarction; NSTEMI, non-ST-elevation MI; STEMI, ST-elevation MI; UDLM, unconstrained distributed lag model.