Airborne microorganisms associated with packaging glass sorting facilities

Abstract

In recent years, efforts have been undertaken to reduce the volume of residual waste through sorting and recycling. The waste management and recycling sector is thriving and the number of workers there is increasing. In this context, prior knowledge of the risks to which workers may be exposed is of crucial importance, and preventive measures need to be put in place to accurately identify and quantify those risks. This study aimed to assess occupational risk of exposure to biological agents (viable bacteria and fungi) in a Portuguese waste packaging glass sorting plant. Air samples were collected from selected locations in waste sorting cabins (critical area, CA), administrative services (noncritical area, NCA) and outdoors (control point, CP). Duplicate air samples were collected through an impaction method. The investigation was carried out over an 8-mo period with two collection periods, autumn/winter (AW) and spring/summer (SS), in order to access the influence of any seasonal variation. In the 36 air samples collected, 319 bacterial and 196 mold identifications were performed. Air samples revealed existence of high environmental contamination by bacteria (1.6 × 104 colony forming units [cfu]/m3) and fungi (1.5 × 104 cfu/m3). The predominant bacterial genus was Staphylococcus (coagulase negative) with values ranging from 29.6 to 60% of the total count of bacteria. Genera Bacillus, Micrococcus, and Staphylococcus (coagulase negative) were also present at all sampling sites, regardless of the season. However, the counts of these genera, in the CA, were higher in warmer seasons. The genus Penicillium was the most frequent genus present with an approximate value of 95% of total fungal count in the CA. Seasonal variation was a significant factor for total bacteria and fungi, except for NCA versus CP. Overall, the highest levels of bacterial and fungal species (104 cfu/m3) were found in the waste sorting cabin (CA). These results highlight the importance of proper design and risk evaluation when planning a new waste facility, such that working conditions minimize proliferation of biological agents in the workplace.