The decision to switch on central air-conditioning units in the government offices should be taken in concurrence with the administrative heads of the ministry or department concerned, according to the guidelines to prevent transmission of COVID-19 issued by the Central Public Works Department (CPWD) on Wednesday.
The CPWD, which constructs and maintains government buildings, issued the guidelines, keeping in view the possibility of the coronavirus spreading through the centralised heating or cooling systems. The guidelines were formulated by a 12-member committee of its officials based on advice of experts like the Indian Society of Heating, Refrigerating and Air Conditioning Engineers.
Peak use
With use of ACs expected to increase in peak summer and monsoon months, the guidelines said “maximum caution should be exercised to minimise the chances of spread of coronavirus through air flow in enclosed spaces like residences, offices, meeting places, assembly places etc.”
The CPWD said the administrative heads of ministries and departments should be apprised of the guidelines and a decision on operating the AC units should be taken with their “concurrence”.
Among the general principles in the guidelines were keeping the temperature of ACs between 24 degrees Celsius and 30 degrees, maintaining a relative humidity of 40-70%, increasing the intake of fresh air and avoiding recirculating of air as much as possible and regular cleaning and sanitisation of filters of indoor units.
For controlled environments with mild exposure risk like residences and standalone offices, the guidelines recommended the use of window-fitted desert coolers or ACs supplemented by fresh air intake through exhaust fans in nearby areas.
In spaces with moderate risk of exposure and concentration like dispensaries and meeting rooms, the guidelines said ACs or desert coolers should be accompanied by opening of windows or doors and exhaust fans to increase fresh air.
The guidelines said the use of central AC systems should be avoided in spaces with “maximum” exposure risk like institutions and malls. If it can’t be avoided, then the AC systems should be used with maximum fresh air as possible and be switched on two hours before and after office timings to ensure no contamination remains.
For hospitals and other medical treatment centres, the Health Ministry guidelines on ventilation and standalone AC units should be followed, it said.
