Recently the impact of ambient fine particles, especially the particulate matter 2.5 (PM2.5), on human health has garnered much attention. Many studies have revealed positive association of PM2.5 with human health outcome, including asthma, pulmonary fibrosis, and cancer. Furthermore, the annual PM2.5 concentration of most cities in Taiwan has been higher than the lowest concentration recommended by the World Health Organization (WHO). The long-term exposure to the ambient fine particles potentially causes more severe inflammation and pulmonary epithelium damage in human lung. This study aims to investigate the association between PM2.5 and human seasonal influenza in cities and counties in Taiwan under the hypothesis that higher exposure concentration is associated with severe lung inflammation and epithelial damage, subsequently humans infected by the influenza virus are likely to have more exacerbating response.
Methodology:
We choose 3 cities/counties from northern Taiwan and 4 cities/counties each from southern and central Taiwan, including Nantou which is the only land-based administrative region in Taiwan. Moreover, five of the six special municipalities in Taiwan are included in the 11 study sites. The weekly human seasonal influenza data from 2009-2015 are retrieved from National Infectious Disease Statistics System of the Taiwan Centers for Disease Control (CDC). The hourly PM2.5 data are retrieved from Taiwan Environmental Protection Administration (EPA). We convert the hourly PM2.5 data into weekly cumulative data in each city/county. Finally, we use Spearman correlation to ascertain the statistical association between influenza incidence rate and PM2.5 in different age groups.
Result:
The association between PM2.5 concentration and influenza incidence rate in all-age group is statistically significant (p-value < 0.05) in southern Taiwan, especially in Yunlin, Chiayi, Kaohsiung, and Pingtung. Moreover, the health risks of adult and the elderly groups seem to increase more significantly in association with regionally higher PM2.5 level in Taiwan.
Conclusion:
Long-term exposure to higher PM2.5 level may lead to more significant increase in human health risk for influenza in Taiwan, especially for the adults and the elderly in Taiwan.
