Abstract

Clean air is necessary for healthy living. Indoor air is prone to bioaerosols, particulate matter (PM) and airborne chemicals. This study evaluated the microbial population and antibiogram of classroom indoor air in three public and three private primary schools in Port Harcourt metropolis. Standard aeromicrobiological methods were employed.  Impactation method using Eco MBV-MAS 100 Microbiologic Air Sampler with medium to culture and enumerate specific bacteria and fungi, FC. Temperature, relative humidity (RH), carbon monoxide (CO), carbon dioxide (CO₂), PM, total volatile organic compounds (TVOCs), formaldehyde (HCHO), air quality index (AQI) and light intensity (LI) were measured with a multidigital analyser. Public and private primary school counts revealed THBC (1.70–3.55 × 10³ CFU/m³;1.21–6.41 × 10² CFU/m³); TFC (2.26–8.86 × 10² SFU/m³;1.36–3.97 × 10² SFU/m³); TCC (7.04–20.8 × 10² CFU/m³; 1.72–5.78 × 10² SFU/m³⁾ and TSC (8.03–53.1 × 10² CFU/m³; 2.53–9.21 × 10² CFU/m³ ). Frequency (%) of occurrence of bacteria were S. aureus (13%), Escherichia coli (12%), Klebsiella (12%), Bacillus amyloliquefaciens (10%), Enterobacter (9%), Proteus (9%), Micrococcus (8%), Pseudomonas aeruginosa (8%), Streptococcus (7%), Serratia marcescens (6%) and Acinetobacter spp. (6%); fungi were Aspergillus spp. (21%), A. niger (18%), Candida (16%), Fusarium (14%), Penicillium (13%), Mucor (10%) and Trichoderma (8%). Physicochemical ranges were; Temperature 25.0–32.0°C, RH 72.0–90.0%, CO 1.0–3.0 ppm, CO₂ 404.33–504.67 ppm, PM10 28.0–38.33 µg/m³, PM2.5 5.0–36.0 µg/m³, TVOC 0.007–0.15 mg/m³, HCHO 0.001–0.01 mg/m³, AQI 30.33–40.67 and LI 4.33–526.67 lux. Microbial counts in public schools exceeded the acceptable standard limits of NESREA, whereas those recorded in private schools were within the acceptable limits. Temperature, RH, CO and PM2.5 exceeded NESREA limits and the USEPA PM2.5 standard. Light intensity was below European Norm 12464-1 except in three public-school classrooms; CO₂, PM10, TVOC, HCHO and AQI were within NESREA limits. Microbial load was likely influenced by each school’s environment, while physicochemical parameters reflected the metropolis’s conditions. Proteus was the most antibiotic susceptible and Klebsiella the most resistant. Presence of high Staphylococcus aureus population in aerosol of classrooms is of public health concern. Therefore, improved classroom hygiene, adequate ventilation and regular environmental sanitation are recommended to maintain healthy indoor air quality.