Potential Health Hazards from Microbial Aerosols in Densely Populated Urban Regions

Abstract

Aerosolized bacteria were recovered up to 930 m downwind of three sewage treatment plants in Jefferson County, Ky. This distance includes homes in the proximity of several hundred such plants in that county. Bacterial counts were elevated on foliage near activated sludge tanks; although these counts decreased rapidly, at 48 h after exposure they were significantly higher than the counts on unexposed leaves. The 50% lethal dose of aerosolized Klebsiella pneumoniae was comparable to the 50% lethal dose of a virulent clinical isolate, and enteric bacteria were recovered from the respiratory organs of mice after forced inhalation adjacent to an aerated sludge tank. The coliform density in the effluents of the plants tested was inversely related to the airborne bacterial load at those plants. This relationship was attributed to the correlation between effluent quality and extent of aeration of activated sludge. Wind direction and distance influenced the airborne counts, but the extreme variation in counts indicates that it is not possible to predict emission rates accurately in an open ecosystem. Airborne enteric bacteria also were isolated near a decorative fountain used by humans for wading. The discovery of these sources of aerosolized microorganisms from polluted waters in densely populated areas suggests that a potential health hazard may be created by the increased probability of inhaling and ingesting microorganisms of fecal origin.

Metagenomic Analysis of the Airborne Environment in Urban Spaces

“…Airborne microbial communities have not been as well characterized as organisms present in soil or aquatic environments [ 1 – 4 ], in part due to the difficulty associated with obtaining sufficient material for study. Previous studies have performed the culture-based examination of airborne microbial populations relevant to agricultural environments [ 5 , 6 ], city settings [ 7 , 8 ], and meteorological conditions [ 9 , 10 ]. Many aerosolized organisms may, however, be difficult to culture, and there has been an increasing interest and an expanding technical capacity for metagenomic surveys of aerosol environments.…”

Effect of an activated sludge wastewater treatment plant on ambient air densities of aerosols containing bacteria and viruses

“…Many other sources of microorganism-containing aerosols are, however, generated through human activities in both urban and rural areas (8,9). Population growth in urban areas has increased the density of domestic wastes which must be disposed of in a safe and environmentally sound manner.…”

Compromised Ecosystem Services From Urban Aerial Microbiomes: A Review of Impacts on Human Immune Function

“…Clearly, contact with airborne pathogens can cause disease (Kim et al, 2018): SARS-CoV-2, influenza, anthrax, tuberculosis and other pathogens can be airborne. Furthermore, exposure to high levels of specific fungi or bacteria can contribute to allergies (Jaakkola et al, 2010), asthma (Karvala et al, 2010;Tham et al, 2014 and citations therein) and systemic disease (Cronholm, 1980;Rylander, 2006;Smit et al, 2006).…”