On the association between outdoor PM2.5 concentration and the seasonality of tuberculosis for Beijing and Hong Kong

Siming You; Yen Wah Tong; Koon Gee Neoh; Yanjun Dai; Chi-Hwa Wang

doi:10.1016/j.envpol.2016.08.071

On the association between outdoor PM_2.5 concentration and the seasonality of tuberculosis for Beijing and Hong Kong

Environ Pollut. 2016 Nov:218:1170-1179. doi: 10.1016/j.envpol.2016.08.071. Epub 2016 Aug 29.

Authors

Siming You¹, Yen Wah Tong², Koon Gee Neoh², Yanjun Dai³, Chi-Hwa Wang⁴

Affiliations

¹ NUS Environmental Research Institute, National University of Singapore, 1 Create Way, Create Tower, #15-02, 138602, Singapore.
² Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore.
³ School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, China.
⁴ Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore. Electronic address: chewch@nus.edu.sg.

PMID: 27595179
DOI: 10.1016/j.envpol.2016.08.071

Abstract

Tuberculosis (TB) is still a serious public health problem in various countries. One of the long-elusive but critical questions about TB is what the risk factors are and how they contribute for its seasonality. An ecologic study was conducted to examine the association between the variation of outdoor PM_2.5 concentration and the TB seasonality based on the monthly TB notification and PM_2.5 concentration data of Hong Kong and Beijing. Both descriptive analysis and Poisson regression analysis suggested that the outdoor PM_2.5 concentration could be a potential risk factor for the seasonality of TB disease. The significant relationship between the number of TB cases and PM_2.5 concentration was not changed when regression models were adjusted by sunshine duration, a potential confounder. The regression analysis showed that a 10 μg/m³ increase in PM_2.5 concentrations during winter is significantly associated with a 3% (i.e. 18 and 14 cases for Beijing and Hong Kong, respectively) increase in the number of TB cases notified during the coming spring or summer for both Beijing and Hong Kong. Three potential mechanisms were proposed to explain the significant relationship: (1) increased PM_2.5 exposure increases host's susceptibility to TB disease by impairing or modifying the immunology of the human respiratory system; (2) increased indoor activities during high outdoor PM_2.5 episodes leads to an increase in human contact and thus the risk of TB transmission; (3) the seasonal change of PM_2.5 concentration is correlated with the variation of other potential risk factors of TB seasonality. Preliminary evidence from the analysis of this work favors the first mechanism about the PM_2.5 exposure-induced immunity impairment. This work adds new horizons to the explanation of the TB seasonality and improves our understanding of the potential mechanisms affecting TB incidence, which benefits the prevention and control of TB disease.

Keywords: PM(2.5); Public health; Seasonality; Tuberculosis.

MeSH terms

Air Pollutants* / analysis
Air Pollution, Indoor / analysis
Beijing
Hong Kong
Humans
Particulate Matter*
Regression Analysis
Risk Factors
Seasons*
Tuberculosis / etiology*

Substances

Air Pollutants
Particulate Matter