Evidence for an association between air pollution and daily stroke admissions in Kaohsiung, Taiwan.
OBJECTIVE
Many studies have reported increases in daily cardiovascular mortality and hospital admissions associated with increases in levels of air pollutants. However, little is known about the relationship between hospital admissions for stroke and air pollution. This study was undertaken to determine whether there is an association between air pollution and hospital admissions for stroke in Kaohsiung, Taiwan.


METHODS
Data on a total of 23 179 stroke admissions were obtained for the period 1997 through 2000. The relative risk of hospital admissions was estimated with a case-crossover approach.


RESULTS
In the single-pollutant models, on warm days (> or =20 degrees C), significant positive associations were found between levels of PM10, NO2, SO2, CO, and O3 and both primary intracerebral hemorrhage and ischemic stroke admissions. On cool days (<20 degrees C), only CO levels and ischemic stroke admissions were significantly associated. For the 2-pollutant models, PM10 and NO2 remained consistently and significantly associated with admissions for both types of stroke on warm days. We observed estimated relative risks of 1.54 (95% confidence interval [95%], 1.31 to 1.81) and 1.56 (95% CI, 1.32 to 1.84) for primary intracerebral hemorrhage for each interquartile range increase in PM10 and NO2. The values for ischemic stroke were 1.46 (95% CI, 1.32 to 1.61) and 1.55 (95% CI, 1.40 to 1.71), respectively. The effects of CO, SO2, and O3 were mostly nonsignificant when either NO2 or PM10 was controlled for.


CONCLUSIONS
This study provides an association between exposure to air pollution and hospital admissions for stroke.
Tsai
Shang-Shyue
SS
Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Goggins
William B
WB
Chiu
Hui-Fen
HF
Yang
Chun-Yuh
CY
D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis; D002545:Brain Ischemia / Q000175:diagnosis / Q000453:epidemiology; D015984:Causality; D002543:Cerebral Hemorrhage / Q000175:diagnosis / Q000453:epidemiology; D018592:Cross-Over Studies; D004784:Environmental Monitoring / Q000706:statistics & numerical data; D062665:Epidemiological Monitoring; D006801:Humans; D016017:Odds Ratio; D010343:Patient Admission / Q000706:statistics & numerical data* / Q000639:trends; D012306:Risk; D018570:Risk Assessment; D020521:Stroke / Q000175:diagnosis / Q000453:epidemiology*; D013624:Taiwan / Q000453:epidemiology; D013696:Temperature; D014887:Weather