The Indoor Concentration and Size Distribution of Airborne Bacteria in a Typical Traditional Market

Abstract

Bioaerosols generated by fresh foods in traditional wet markets (TWMs) in Taiwan are classified as significant biological contaminants and can lead to biological hazard risk. This study aims to explore the distribution of the different particle sizes of airborne bacteria (AB) present at typical public indoor TWM. The concentrations during operations at the chosen indoor TWM were measured to be 1.55 × 103 CFU m–3 of AB. The presence of AB in the environment was influenced by the specific products being sold, particularly in areas where vendors sold fresh poultry and livestock meat. These areas exhibited a higher concentration of AB. Although the AB concentrations were comparable to Taiwan indoor air quality standards, the size distribution of AB indicated a potential biological hazard for the staff working with poultry and livestock meat. The size distribution analysis revealed that the highest frequency of bioaerosols was observed within the range of 2.1 to 3.3 µm, accounting for 25.76% of all AB during TWM operation and 22.79% after operations were completed. The main bacterial source came from the excrement produced by the live poultry around these sampling points. The second highest proportion was in the range of 1.1 to 2.1 µm. These two sizes of particles are highly likely to deposit in the bronchial tubes of the respiratory tract after being inhaled by humans. Among the AB sampled, isolated and identified were Kocuria marina, K. carniphila, and Staphylococcus sciuri, which were frequently found in a typical indoor TWM. We recommend using these representative AB as biological indicators for monitoring public indoor TWMs in Taiwan. It is important to enhance the effective management of environmental sanitation during and after operations in TWMs. This can be achieved through makes such as proper waste collection and disposal, as well as the installation of mechanical ventilation systems.