Re ECF Project: 2015-17

Project Title: Characterization of the composition and seasonal dynamics of the microorganisms associated with PM2.5 and PM10 air pollutants in Hong Kong

Applicant: Dr LEE Kwan Hon Patrick, School of Energy and Environment, City University of Hong Kong

Total Approved Grant: $499,900

Duration: 1/7/2016 to 31/12/2017

Project Status/Remarks: Completed

The objective of this project is to analyze the microorganisms associated with outdoor particular matters in ambient air at eight different outdoor locations in Hong Kong over four seasons using advanced DNA sequencing technology. The biological data will be correlated with the chemical data from air quality monitoring stations. The significance of this study is that it will add to our understanding of the air pollutants in Hong Kong and allow the appropriate preventive measures to be taken to protect public health.

Summary of the Findings/Outcomes:
In this study, the research team systematically characterized the bacteria that were present in aerosols using advanced DNA sequencing technique. DNA sequencing overcomes the problem that most bacteria cannot be cultivated in the laboratory; hence, the DNA data in this study provide a more accurate view of the bioaerosol content. Bioaerosol samples were collected at eight different geographical locations across Hong Kong (Mong Kok, Tsuen Wan, Tai Kok Tsui, Tsim Sha Tsui, Sha Tin, Causeway Bay, Tuen Mun, and Tsim Sha Tsui East) on three consecutive days during each of the four seasons. The major bacteria associated with bioaerosol were originated from humans, accounting for ~45%, and bacteria from environmental sources were substantially lower. Some day-to-day and seasonal variations of the abundant bacteria associated with the bioaerosols were observed, but the dominant bacteria remained similar. Seasonality was a major factor affecting the composition and number of types of bacteria present in bioaerosols, while geographical location was less influential. Composition of the bioaerosols exhibited distance-decay characteristics in the North-South transect, meaning bioaerosols farther apart were less similar. Specific bacteria were positively correlated with PM2.5 concentration. Results of this study were disseminated in a public seminar in June 2018 at the City University of Hong Kong.