Airborne Bacteria and Fungi in Urban Area of Kathmandu

Abstract

Air is essential for life, yet its quality is declining due to rapid urbanization, population growth and poor sanitation practices. This deterioration increases various serious skin and respiratory diseases due to the presence of pathogenic airborne bacteria and fungi. The present study aimed to assess and compare the bacterial and fungal load in three different sites Asan, Kamaladi Ganesh Mandir, and Tri-Chandra Multiple campus. Air samples were collected during March to May 2025 by the gravity settle plate method using Nutrient agar, MacConkey agar and Potato dextrose agar plates were exposing for 15 minutes each. Nutrient agar bacteria were identified by conventional morphological and biochemical tests. A total of 147 bacterial and 126 fungal isolates were identified. The bacterial concentration ranged from 640 to 4x10⁴ CFU/m³, while fungal concentrations ranged from 8.4x10² to 4.9x10³ CFU/m³. The dominant bacterial isolates were Bacillus spp. and Micrococcus spp. whereas Aspergillus (21.4%) was the most dominant fungi and followed by Fusarium (18.25%), Penicillium (15.9%), Cladosporium (15.1%), Mucor (14.3%), Rhizopus (8.7%) and Alternaria (6.4%). The highest fungal load 2.6x10⁴ CFU/m³ was recorded in Asan with mean bacterial load 2.15x10⁴ CFU/m³ followed by 1.9x10⁴ CFU/m³ fungal load in Kamaladi Ganesh Mandir with 3.6x10³ CFU/m³ mean bacterial load and academic sites, Tri Chandra Multiple Campus had a fungal load 1.96x10⁴ CFU/m³ and 2.4x10³  CFU/m³ mean bacterial load. From the above findings, it was clear that airborne bacteria and fungi were higher in improper urbanization, reduced air movement and poor sanitation practices. So, the policy of proper urbanization, planting green vegetation, allowing better air flow and sanitation practices should be implemented to reduce the microbial load in the surrounding air.