Objective To assess the short-term effect of ambient PM2.5 mass concentration on influenza-like illness occurrence in Shenzhen.
Methods Records of meteorological factors and ambient PM2.5 levels were collected in Shenzhen from 2013 to 2014. Influenza-like illness reports during the same period were collected from 18 surveillance sites weekly. The relationship between PM2.5 concentration and reported influenza-like illness person-time was analyzed using generalized additive model with Poisson distribution. RR (95%CI) values were calculated. The effect of PM2.5 mass concentration on influenza-like illness for each age group were also assessed.
Results During the study period, a total of 214 456 influenza-like illness person-times were recorded. The weekly average mass concentration of PM2.5 was 36.8 μg/m3. After adjusting meteorological variables such as temperature and relative humidity, an IQR (29.3 μg/m3) increment of PM2.5 mass concentration was associated with reporting more influenza-like illness cases:RR=1.092 5 (95%CI:1.080 0-1.105 2) for all, 1.115 2 (95%CI:1.096 5-1.134 1) for 0-4 years age group, 1.053 8 (95%CI:1.029 0-1.079 3) for 5-14 years age group, 1.148 7 (95%CI:1.109 4-1.189 3) for 15-24 years age group, and 1.086 1 (95%CI:1.0591-1.113 8) for 25-59 years age group, respectively.
Conclusion Ambient PM2.5 mass concentration has a short-term effect on influenza-like illness cases for all age groups in Shenzhen. There may be a correlation between ambient PM2.5 and influenza-like illness.
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