Air-conditioning units in tropical regions create indoor environments which serve as breeding grounds for microbial pathogens that increase chances of disease spread in healthcare settings. This study compared microbial contamination in AC units from health and non-health facilities in Calabar, Nigeria. A cross-sectional study design was adopted and a sample size of 115 AC units (67 health, 48 non-health) was used. Swabs from filters, coils, and pans were cultured on selective media. Isolates were identified biochemically and morphologically. Data were analyzed using chi-square tests (P<0.05). Result shows that contamination affected 40% (46/115) of units, with 41.8% in health vs. 37.5% in non-health facilities (P=0.60). Bacteria predominated (39 isolates) were Staphylococcus aureus (43.6%), Pseudomonas aeruginosa, Klebsiella spp. (23.1% each), Legionella spp. (7.7%) and Bacillus spp. (2.6%). While the fungi (7 isolates) included, Aspergillus flavus (57.1%) and Penicillium spp. (42.9%). Co-contamination occurred in 5.2%. Health facilities showed higher bacterial loads, but differences were non-significant (P>0.05). The study concludes that AC units in Calabar harbor pathogenic microbes, with health facilities at marginally higher risk. Thus, routine maintenance is crucial to prevent bioaerosol-related infections in tropical settings.

• Air-conditioning