Quantity of Airborne Microorganisms in Public Transport of Moscow in Winter Period

Abstract

This article analyzes airborne microorganisms in Moscow public transport and identifies factors affecting their quantitative and group composition. The sedimentation method based on gravitational settling of air-suspended particles on an agar medium was applied. Microorganisms were distinguished: 1) saprotrophic bacteria (B25); 2) potentially pathogenic bacteria (B37) 3) mycelial fungi (MF). Air sampling was carried out on 4 metro lines and 4 bus routes inside buses and trains and on platforms and bus stops. The number of microorganisms in the air of buses (2463 ± 1041 CFU m^-3) was twice that in the air of trains (1230 ± 581 CFU m^-3). The outdoor air at bus stops (10328 ± 5704 CFU m^-3) and on subway platforms (3882 ± 1859 CFU m^-3) had a significantly higher content of microorganisms compared to the indoor air. Inside vehicles B25 was found in the largest numbers, there were smaller numbers of B37 and MF had the smallest numbers. The quantity of microorganisms inside transport complied with the Russian subway regulations; but on platforms and at bus stops it was significantly higher. The levels of air pollution based on EU regulations were identified (bacteria/fungi): medium/low — inside; high/low — on platforms; high/high — at bus stops. The dominant factor affecting the number of microorganisms inside transport is the number of microorganisms in the ambient air of the urban environment. Significant correlations with air temperature, the duration of the route and the number of people in the vehicle were not detected.
This article will be useful for specialists in urban studies, as it reflects the connections between the organization of urban spaces and the number of microorganisms in the air. Such measures as open soils and ground fixing with grass cover, the protection of lawns from the unauthorized parking of vehicles and foot traffic, and the minimization of inefficient engineering activities in the city will help reduce the level of dust and the microbiological pollution of urban air.