Image: City of Busan ()
The Busan Metropolitan City Health and Environment Research Institute announced that it investigated the total airborne bacteria items in the indoor air twice in August and November-December of last year to review the safety of respiratory diseases in urban railway vehicles and improve indoor air quality hygiene.
As interest in respiratory infectious diseases such as COVID-19 has recently increased, this survey is meant as an indirect indicator of indoor air quality hygiene in addition to ultrafine dust (PM-2.5) and carbon dioxide items, which are items of urban railway indoor air quality investigation.
An additional study was conducted on the item ‘total floating bacteria’.
As a result of the survey, the average concentration of total airborne bacteria was 378 CFU/m3 for subway line 1, 282 CFU/m3 for line 2, 298 CFU/m3 for line 3, and 164 CFU/m3 for line 4, which are standards for maintaining indoor air quality in medical institutions, etc.
It is a value judged to be hygienically safe below 800 CFU / ㎥ of phosphorus.
In addition, it was analyzed that there was no significant correlation between passenger congestion and airborne bacteria. It is believed that this is because bacterial contamination factors such as cough droplets are effectively blocked by passengers wearing masks and the effect of indoor air quality purifiers installed in each vehicle.
As a result of a laboratory simulation test conducted separately, the increase in total airborne bacteria was negligible in simple breathing, and the total airborne bacteria increased significantly in the coughing state.
Based on the results of this investigation, in order to manage total floating bacteria in urban railway vehicles, passenger hygiene guidance, such as wearing masks, is required.
Since it can proliferate, it was stated that it is necessary to maintain sanitary management of stations, such as reducing indoor dust through the improvement of station facilities, operating and cleaning ventilation facilities.
