RESUMO
BACKGROUND: Ambient air pollution has posed negative effects on human health. Individual-level factors may modify this effect, but previous studies have controversial conclusions, and evidence is lacking especially in developing countries. This study aims to examine the modifying effects of sex, age, and education level of individuals on the associated between daily mortality and air pollutants, including particulate matter < 10 µm in aerodynamic diameter (PM10), sulfur dioxide (SO2), and nitrogen dioxide (NO2). METHODS: Time-series analysis was conducted to investigate the acute effects of the air pollution on daily mortality from January 2002 to December 2010 in Wuhan, China. Generalized Additive Models (GAM) were used to examine the association stratified by sex for non-accidental, cardiovascular, and respiratory mortality. For non-accidental mortality, stratified analysis was also conducted by age and educational level. RESULTS: Outdoor air pollution was associated with daily non-accidental and cardiovascular mortality. An increase of 10 µg/m3 in a 2-day average concentration of PM10, SO2, and NO2 was corresponding to the increase in non-accidental mortality of 0.29% (95%CI: 0.06-0.53%), 1.22% (95%CI: 0.77-1.67%) and 1.60% (95%CI: 1.00-2.19%), respectively. The effects of air pollution were faster in females than males. The magnitude of the estimates was higher for females with low education, aged 65-75 years for PM10 and < 65 years for SO2. To be more specific, we observed that per 10 µg/m3 increase in SO2 was association with increases in non-accidental mortality of 2.03% (95%CI: 1.38-2.67) for all females and 3.10% (95%CI: 2.05-4.16) for females with low education. CONCLUSION: Females and people with low-education are more susceptible to the effect of air pollution, which would provide a sound scientific basis for determination of air pollution standards.
RESUMO
BACKGROUND: There was no consistent definition for heat wave worldwide, while a limited number of studies have compared the mortality effect of heat wave as defined differently. This paper aimed to provide epidemiological evidence for policy makers to determine the most appropriate definition for local heat wave warning systems. METHODS: We developed 45 heat wave definitions (HWs) combining temperature indicators and temperature thresholds with durations. We then assessed the impact of heat waves under various definitions on non-accidental mortality in hot season (May-September) in Wuhan, China during 2003-2010. RESULTS: Heat waves defined by HW14 (daily mean temperature ≥ 99.0th percentile and duration ≥ 3 days) had the best predictive ability in assessing the mortality effects of heat wave with the relative risk of 1.63 (95% CI: 1.43, 1.89) for total mortality. The group-specific mortality risk using official heat wave definition of Chinese Meteorological Administration was much smaller than that using HW14. We also found that women, and the elderly (age ≥ 65) were more susceptible to heat wave effects which were stronger and longer lasting. CONCLUSION: These findings suggest that region specific heat wave definitions are crucial and necessary for developing efficient local heat warning systems and for providing evidence for policy makers to protect the vulnerable population.
