The effect of sandstorms and air pollution on cause-specific hospital admissions in Taipei, Taiwan

OBJECTIVE: Relatively little research exists focusing on the impact of air pollution on hospital admissions in Asia compared to the extensive work conducted in the USA and Europe. The issue is of particular importance because of the frequency, intensity and health effects of Asian sandstorms. This work investigates the relation between cause-specific hospital admissions and sandstorms and air pollution in Taipei, Taiwan's capital. METHODS: Time-series analyses of asthma, pneumonia, ischaemic heart disease and cerebrovascular disease hospital admissions were performed for Taipei. An eight-year time period (1995-2002) was considered for various indicators of sandstorms and the pollutants NO(2), CO, ozone, SO(2), PM(10), and PM(2.5). Pollution effects based on single-day lags of 0, 1, 2 and 3 days were explored, along with the average of the same day and previous three days (L03). RESULTS: The risk of ischaemic heart disease admissions was associated with several sandstorm metrics, including indicators of high PM(10) levels in the Taipei area, indicators of high PM(10) at a monitor designed to measure background pollution, the PM coarse fraction, and the ratio of PM(10) to PM(2.5). However, the lag structure of effect was not consistent across sandstorm indicators. Hospital admissions for this disease were 16-21% higher on sandstorm days compared to other days. This cause was also associated with transportation-related pollutants, NO(2), CO and PM(2.5). Asthma admissions rose 4.48% (95% CI 0.71% to 8.38%) per 28 mug/m(3) increase in L03 PM(10) levels and 7.60% (95% CI 2.87% to 12.54%) per 10 ppb increase in L03 ozone. Cerebrovascular disease admissions were associated with PM(10) and CO, both at lag 3 days. SO(2) exhibited no relation with admissions. CONCLUSIONS: Risk of hospital admissions in Taipei may be increased by air pollution and sandstorms. Additional research is needed to clarify the lag structure and magnitude of such effects.