Environmental study in subway metro stations in Cairo, Egypt

Airborne viable and non-viable measurements were carried out in two different metro stations, one located in a tunnel and the other on the surface. The concentrations of airborne total viable bacteria (incubated at 37degreesC and 22degreesC), staphylococci, suspended dust and oxidants (ozone) were higher in the air of the tunnel station than those recorded at the surface station. In contrast, spore forming bacteria, Candida spp, fungi and actinomycetes were found at slightly higher levels in the surface station than in the tunnel station. A statistically significant difference (p<0.01) was found between the levels of suspended dust at both stations. Cladosporium, Penicillium and Aspergillus species were the dominant fungi isolates. Fusarium, Aspergillus and Penicillium are the most common fungi that produce toxins. Under certain circumstances (host susceptibility, infective dose and aerodynamic diameter) some of the airborne microorganisms e.g. actinomycetes and Aspergillus species and staphylococci may cause health problems in exposed persons based on toxic or allergic reactions.