Effects of PM2.5 and temperature on the incidence of severe asthma in adults and the elderly in Shanghai, China: A retrospective study

Abstract

Background The study aimed to investigate the correlation between both particulate matter (PM) 2.5 and temperature and the incidence of severe asthma as diagnosed by fractional exhaled nitric oxide (FeNO) values of >50 parts per billion. Methods This large-scale retrospective study used data on PM2.5 and temperature from the Shanghai Meteorological Bureau in China that had been collected between May 2014 and April 2016. All patients with suspected airway inflammation, who had visited the Minhang branch of Zhongshan Hospital, an affiliation of Fudan University, between May 2014 and April 2016, were retrospectively enrolled in this study. Spearman’s rank correlation coefficient and multiple linear regression models were used to analyze the synergistic effect of PM2.5 and temperature on the incidence of severe asthma in the different subgroups of patients with suspected airway inflammation. Results PM2.5 and temperature were significantly correlated with the incidence of asthma in the Oldabove50 subgroup (Spearman’s r = 0.580, p = 0 .003 and Spearman’s r = -0.689, p ≤ 0.001, respectively), when analyzed using non-parametric statistical analysis methods. The combined effect of PM2.5 and temperature on the incidence of asthma was significantly greater in the Oldabove50 subgroup (R = 0.693) than in the Adultabove50 subgroup (R = 0.275) (F > Fα; Fα = 2.997066, p < 0.05). In particular, in the Oldabove50 subgroup, the effect of temperature on the incidence of asthma was greater than that of PM2.5, when using beta coefficients (p = 0.004). Conclusions The FeNO cut-off value can be used to determine the effect of PM2.5 and temperature on patients’ respiratory health. Although the study’s limitations may have impacted these findings, and further investigation is necessary, this study provided a convenient investigation into the epidemiology of asthma. Such research is important for public health.