Pooled percentage change (95% CI) in respiratory hospitalisations for all ages and by age group in five European cities per 10 000 increase in ultrafine particle concentration per cm3, stratified by the warm and cool period of the year
| Lags | All ages | 0–14 years | 15–64 years | ≥65 years |
| Warm period (April–September) | ||||
| 0 | 1.80 (−0.85–5.42)# | 6.38 (1.53–11.46) | −0.19 (−4.24–4.04)# | 1.24 (−1.40–3.96)# |
| 1 | 2.68 (−0.26–5.71)# | 6.17 (0.34–12.33) | 0.52 (−3.81–5.05)# | 2.39 (0.11–4.71) |
| 2 | 4.27 (1.68–6.92)# | 6.95 (2.21–11.91) | 3.11 (0.63–5.65) | 4.02 (0.21–7.98)# |
| 3 | 3.82 (2.54–5.12) | 5.92 (2.74–9.20) | 2.82 (0.38–5.32) | 4.56 (1.52–7.68)# |
| 4 | 3.57 (1.83–5.34) | 6.69 (3.51–9.96) | 3.15 (0.72–5.64) | 3.28 (0.09–6.57)# |
| 5 | 3.77 (1.30–6.30)# | 5.27 (−1.68–12.71) | 3.83 (0.24–7.55)# | 2.85 (0.36–5.41)# |
| 6 | 2.73 (1.14–4.35) | 4.92 (1.86–8.08) | 2.87 (0.46–5.34) | 2.34 (0.13–4.61) |
| 7 | 2.36 (1.12–3.62) | 5.87 (−0.60–12.77) | 2.07 (−1.09–5.34) | 1.40 (−0.16–2.98) |
| Cool period (October–March) | ||||
| 0 | −0.76 (−1.87–0.36) | 0.59 (−1.53–2.76) | −1.82 (−4.29–0.71)# | −1.05 (−2.97–0.91)# |
| 1 | −1.14 (−2.37–0.11) | −0.06 (−1.33–1.23) | −0.92 (−3.32–1.54)# | −2.13 (−4.13–−0.09)# |
| 2 | −0.90 (−1.62–−0.17) | 0.17 (−1.07–1.43) | −0.60 (−2.28–1.11) | −1.54 (−2.47–−0.60) |
| 3 | −0.63 (−1.80–0.54) | 0.64 (−0.59–1.87) | −0.75 (−2.00–0.52) | −1.04 (−2.67–0.62) |
| 4 | −0.55 (−1.27–0.17) | 0.92 (−0.30–2.16) | −0.63 (−1.87–0.63) | −1.32 (−2.25–−0.38) |
| 5 | −0.43 (−1.15–0.30) | −0.83 (−5.14–3.67)# | 0.70 (−1.22–2.66) | −0.79 (−2.32–0.77) |
| 6 | 0.00 (−1.13–1.15) | 1.22 (0.01–2.45) | −0.27 (−1.52–0.99) | −0.31 (−3.09–2.55)# |
| 7 | −0.73 (−1.97–0.52) | 1.52 (0.30–2.75) | −1.43 (−2.65–−0.20) | −0.81 (−2.75–1.17)# |
#: heterogeneity as defined by I2>40% and p<0.20. Bold indicates statistical significance.