This study was conducted to assess the outdoor air quality of some urban slums in Port Harcourt. Six sampling sites were selected, from the Port Harcourt urban slums; two sites from each slum represented with a suffix 1 or 2. The slums are designated Marine base (#1 and #2), RSU BG, Obudu 2, Bundu (#1 and #2). The air quality was analyzed using portable handheld air quality analyzer and the microbiological parameters were determined by standard cultural method. The study revealed that the sampled sites were laden with bacterial and fungal species. namely; Klebsiella sp., Micrococcus sp., Escherichia sp., Pseudomonas sp., Baccilus sp., Aeromonas sp., Streptococus sp., Serratia sp., Aerococcus sp., Proteus sp. Penicillium sp., Fusarium sp., Candida sp., Aspergillus sp., Mucor sp., Rhizopus sp. and Tricorderma sp. Highest obtained noise level was at Marine base 1 which was 66 db, highest relative humidity of 54.8% at RSU BG, CO2 (ppm) values of 4.8, 80, 796, 850, 638, 698 for Marine base 2, Marine base 1, Obudu 2, RSU BG, Bundu 1 and Bundu 2 respectively. The values for NO2 (ppm) was (0.05, 0.053, 0.071, 0.022, 0.035, 0.023), suspended particulate matter (ppm) was (7.1, 8.7, 9.5, 9.5, 6.2, 6.2), SO2 (ppm) was (0.42, 0.15, 0.50, 0.34, 1.26, 0.41) CO (ppm) was (4.8, 1.7, 2.2, 3.0, 3.9, 3.6) and volatile organic compound (ppm) was (1.0, 1.1, 0.9, 75 and 1.2). This study has shown that Port Harcourt urban slums are experiencing some degree of contamination not acceptable for healthy living that requires attention to curb. These areas require all-round improvement in sanitation. M Give one sentence on methodology.