Making hospital air SARS-CoV-2-freeDecember 5, 2020
The outbreak of SARS-CoV-2 (COVID-19) has made us all think critically about indoor air quality in hospitals as this has an impact on the core functioning of healthcare systems. While specific aspects of coronavirus infectivity, spread and routes of transmission are still under rigorous investigation, it is important to tackle the known mechanisms early on. The prevention of healthcare or hospital-associated infections (HAIs) must be a top priority for every hospital and government across the world. The most recognized modes of transmission of COVID-19 include direct large droplets between individuals within close proximity, indirect respiratory droplet transmission on surfaces and objects and subsequent transmission via the contaminated fomite, and finally airborne transmission via small-particle aerosols containing the viable virus. As reported by Kebarkoohi A et al, hospital indoor air could be a potential source for transmission of viable COVID-19 virus. Healthcare personnel (HCP) caring for patients with or without COVID-19 may be left at high risk for contracting SARS-CoV-2. For example, the SARS pandemic affected hospital staff, which in turn resulted in forced closure of intensive care units (ICUs) and several other hospital systems. Studies by Jin T et al suggest airborne transmission in hospitals, with the presence of virus-carrying aerosols detected for approximately 1.1 to 1.2 hours. This is in spite of masks being worn by infected and recovered patients. There is a significant need to monitor air quality in hospitals for the presence of COVID-19 aerosols. Present technologies do not aid such measurements easily. Jin T et al also showed that, as the main focus was given to COVID-19 positive cases in hospitals, discharged patients with redetectable positive (RP) infections were not observed to the extent required.
Cleaning and air filtration systems in several areas in the hospitals are not regularly evaluated for the presence of COVID-19. Air handling units and filtration systems usually recycle the air and send it back to areas like ICUs and other important patient areas.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recognizes five different spaces in a typical in-patient hospital facility i) surgery and critical care in operating rooms, inpatient and ambulatory diagnostic and therapeutic radiology, and inpatient delivery rooms ii) inpatient nursing including airborne infection isolation rooms (AIIRs), intermediate, critical and intensive care units, iii) protective environments rooms, high-risk immune-compromised patients areas and environmental airborne pathogens iv) laboratories and (v) all other services including administrative, food preparation, laundry and storage spaces. Currently, we do not recognize that air filtration and recirculation requirements for inpatient facilities where COVID patients are likely to be hospitalized need to be changed. As the recirculation of air can cause recurrent and other co-infections, the minimum efficiency reporting value rating (MERV) for air filtration systems will need to be reviewed. However, there is no simple electronic instrumentation that can measure air quality and COVID-19 particulate presence in
hospitals. As the COVID-19 virus and its particulates are small (0.25µ in size), the present guidelines (Guidelines for Design and Construction of Hospital and Health Care Facilities from Facility Guidelines Institute – FGI USA) may have to be improved for virus removal. The use of HEPA filters with 99.97% efficiency has been the mode of practice, along with downstream blowers or fans. Inpatients with airborne precautions for possible aerosolizing infections should be in rooms with HEPA filters.