[A case-crossover study on the relationship between air pollution and acute onset of cerebral hemorrhage in Hangzhou city].

OBJECTIVE

To explore the relationship between air pollution and acute onset of cerebral hemorrhage in Hangzhou.

METHODS

Time-stratified case-crossover study was used to analyze the effect of aerosol optical depth (AOD), PM(10), SO(2) and NO(2) on the acute onset of cerebral hemorrhage. Conditional logistic regression was used to estimate the odds ratios (ORs) and their 95% confidence intervals (CIs) in relation to an increase of one unit of AOD and 10 microg/m(3) of air pollutants.

RESULTS

After adjusted temperature and relative humidity, the ORs of acute onset of cerebral hemorrhage by a unit increase in AOD at a 2 day-lag were 1.727 (95%CI: 1.103 - 2.703) in first half year and 2.412 (95%CI: 1.230 - 4.733) at a 2 day-lag in spring. For a 10 microg/m(3) increase in SO(2), the ORs were 1.119 (95%CI: 1.019 - 1.229), 1.230 (95%CI: 1.092 - 1.386), 1.254 (95%CI: 1.076 - 1.460) in the whole year (2 day-lag), in first half year (2 day-lag) and in spring (2 day-lag), respectively. NO(2) exposure in first half year (2 day-lag) was associated with cerebral hemorrhage, with OR as 0.841 (95%CI: 0.734 - 0.964). However, there were no statistical significances for AOD, SO(2), NO(2) in the rest time-periods (P > 0.05). Additionally, no association was found between PM(10) and the acute onset of cerebral hemorrhage in any time-periods (P > 0.05).

CONCLUSION

Our data showed that there was association between air pollution and the acute onset of cerebral hemorrhage, especially in spring and in the first half of the year.