Bacterial bioaerosol concentration and size distribution in the selected animal premises in a zoological garden

Currently, there are almost no studies concerning bioaerosol and particulate matter levels in animal enclosures of zoos. Numerous air contamination sources can be found there, and zoos are both working environments and popular tourist objects. The aim of this study was to assess bacterial aerosol levels in premises for animals (giraffes, monkeys, pheasants and ostriches) of the Krakow Zoo. Bioaerosol samples were collected using six-stage Andersen impactor to assess the concentration and size distribution of airborne mesophilic bacteria, Gram-negative bacteria and staphylococci. Particulate matter levels (PM10, PM4, PM2.5 and PM1) were assessed using DustTrak Aerosol Monitor. The results showed that the concentration of airborne bacteria varied significantly between enclosures for the analyzed animal groups and various groups of bacteria reached their maximum concentrations in premises for different animals. The mean share of respirable fraction of bacteria was quite high68%, with values ranging from 12.8% for Gram-negative bacteria to 98% for mannitol-positive staphylococci, indicating potential harmfulness to the health of exposed people. Dust concentrations remained at similar, relatively low levels (maximum of 0.105mg/m(3) for PM10 in rooms for giraffes). This study showed that neither bacterial bioaerosol levels, nor dust concentrations exceed the permissible values provided by Polish guidelines, but comparing the values with other countries' limits suggests that the air could be considered as contaminated. The animals are a significant source of bioaerosol; therefore, attention should be paid to thorough cleaning of animals themselves and their premises and to maintaining appropriate levels of microclimatic parameters prevailing in the rooms.