Association between 24-hour mean concentrations of air pollutants and death due to stroke (Model A)
| Variables included in the multi-pollutants model* | Intracerebral haemorrhage | Ischaemic stroke | ||||||
|---|---|---|---|---|---|---|---|---|
| (ICD-9 code 431) | (ICD-9 code 434) | |||||||
| OR | (95% CI) | OR | (95% CI) | |||||
| *Variables included in the model are 24-hour PM7, 24-hour Ox, 24-hour NO2, 24-hour temperature, and 24-hour relative humidity. | ||||||||
| †PM7: Defined under the Japanese Air Quality Standard as any particles collected with an upper 100% cut-off point of 10 μm aerodynamic diameter. The 50% cut-off diameter for the particles is assumed to be approximately 7 μm (PM7). | ||||||||
| ‡Ox, photochemical oxidants; RH, relative humidity. | ||||||||
| §Categorised by quartile and to examine extreme temperature highest 1% and lowest 1% were also categorised. | ||||||||
| ¶p<0.05. | ||||||||
| Warmer months (April to September) | ||||||||
| 24-hour PM7† | Increment | 30 μg/m3 | 1.041 | (0.984–1.102) | 1.027 | (0.993–1.062) | ||
| 24-hour NO2 | Increment | 10 ppb | 0.995 | (0.955–1.037) | 0.995 | (0.971–1.019) | ||
| 24-hour Ox ‡ | Increment | 10 ppb | 0.996 | (0.961–1.033) | 0.975 | (0.955–0.996)¶ | ||
| Temperature§ | ||||||||
| <0°C (0–1%) | – | (–) | – | (–) | ||||
| 0–8°C (1–25%) | 1.253 | (0.938–1.674) | 1.074 | (0.904–1.275) | ||||
| 8–15°C (25–50%) | 1.054 | (0.948–1.172) | 0.993 | (0.931–1.059) | ||||
| 15–22°C (50–75%) | Reference | 1.000 | 1.000 | |||||
| 22–30°C (75–99%) | 0.940 | (0.865–1.023) | 0.993 | (0.945–1.043) | ||||
| >30°C (99–100%) | 1.153 | (0.937–1.420) | 1.133 | (1.002–1.280)¶ | ||||
| RH‡ | Increment | 10% | 0.961 | (0.881–1.048) | 0.931 | (0.884–0.981)¶ | ||
| Colder months (October to March) | ||||||||
| 24-hour PM7† | Increment | 30 μg/m3 | 1.005 | (0.951–1.061) | 1.005 | (0.973–1.039) | ||
| 24-hour NO2 | Increment | 10 ppb | 1.025 | (0.976–1.077) | 1.000 | (0.971–1.030) | ||
| 24-hour Ox ‡ | Increment | 10 ppb | 1.010 | (0.950–1.033) | 1.006 | (0.970–1.044) | ||
| Temperature§ | ||||||||
| <0°C (0–1%) | 0.498 | (0.199–1.247) | 0.974 | (0.666–1.425) | ||||
| 0–8°C (1–25%) | 1.225 | (1.082–1.386)¶ | 1.058 | (0.984–1.138) | ||||
| 8–15°C (25–50%) | 1.098 | (0.987–1.221) | 1.037 | (0.974–1.104) | ||||
| 15–22°C (50–75%) | Reference | 1.000 | 1.000 | |||||
| 22–30°C (75–99%) | 0.819 | (0.668–1.006) | 0.933 | (0.830–1.048) | ||||
| >30°C (99–100%) | – | (–) | – | (–) | ||||
| RH‡ | Increment | 10% | 0.935 | (0.866–1.009) | 0.981 | (0.936–1.028) | ||