Seasonal evaluation of fine and coarse culturable bacterial aerosols from residences within a rural and an urban city in Egypt.

Non-complaint Egyptian homes were examined to determine the residential culturable airborne bacterial concentrations so that these could be used as comparisons in indoor air quality investigations. Concentrations of airborne bacteria were investigated in 26 urban flats across Cairo and 17 rural flats in the Dakahlia governorate. Air samples were collected using a two-stage viable cascade impactor sampler, dividing particles into coarse (>8 μm) and fine (<8 μm) sizes. For urban flats, the year's median indoor and comparison site concentrations were 9133 CFU/m(3) and 9423 CFU/m(3), respectively. For rural flats, the year's median indoor and comparison site concentrations were 15,915 CFU/m(3) and 10,859 CFU/m(3), respectively. The median indoor bacterial concentrations increased in winter and spring compared to autumn and summer. Winter months had the greatest median concentration for coarse indoor organisms, whereas spring had the largest for the fine indoor organisms. Fine bacterial concentration composed more than 60% of the indoor bacterial fraction.