Indoor air hygiene- the new ‘risk’ marker
The outbreak of COVID-19 has highlighted the importance of Indoor Air Quality (IAQ) as it is now established by the medical fraternity and researchers that there is high transmissibility of this virus in indoor areas and this happens through air-borne droplets.
SARS-CoV-2 virus mainly spreads via respiratory droplets which are released when an infected person coughs or sneezes. Such droplets can remain suspended in form of an aerosol (as studies show) which can remain airborne for a long duration and can travel in certain cases up to 30 feet, unlike what was assessed earlier.
Health authorities have singled out indoor areas like workplaces, auditoriums, halls/rooms, shopping malls, retail outlets, hotels, restaurants, etc. with poor ventilation as potential COVID-19 infection hotspots.
As per multiple research findings, amongst many constituents of indoor air, particulate matters (PM2.5 & PM10) and Carbon Dioxide play a significant role in enhancing the infection risk to occupants in indoor space.
Additionally, other toxic gases such as volatile organic compounds (VOCs) that are commonly found in workplaces, shopping areas, auditoriums, restaurants, and hotels have a serious health impact on the occupants and could dull cognitive abilities of the occupants as studies have established. (Source: HARVARD T.H CHAN, School of Public Health)
THE SCIENCE BEHIND THE RISK — ROOT CAUSE
World Health Organization (WHO) has mentioned in a report (WHO EPI March 2020) that respiratory droplet transmission of COVID-19 can occur when a person is in close contact with an infected person.
In an indoor office environment, a symptomatic occupant can exhale viruses in the form of aerosols along with CO2. These virus-laden aerosols can easily accumulate at places of circulation like lifts, lobbies, staircases, etc.
Other occupants can be easily infected by inhaling these virus-laden aerosols.
Practicing Indoor Air Quality measurement, monitoring, and validation
ASHRAE recommends Carbon dioxide (CO2) monitoring as a reference indicator of the adequacy of ventilation systems. Since carbon dioxide is produced by human respiration, the amount of carbon dioxide can be easily used as an indicator to determine the adequacy of fresh air ventilation in an indoor environment.
Studies as mentioned earlier also infer that the level of particulate matters (PM) in indoor environment is also a potential marker for aerosol transmission.
Therefore, Monitoring of PM 2.5 & PM 10 through periodic measurements, analyzing the trends of these parameters in the most frequented areas like reception, auditorium, cafeteria, pantry, washrooms etc. will likewise lead to measures that can help in controlling these particulate matters.
Consequently, measurement, monitoring, and trend analysis of these key IAQ parameters like temperature, humidity CO2, and PPM (2.5 &10) by handheld/mobile AQI sensors (over and above the measurements recorded thru the Building Management System) at random spots.
Where the IAQ/ BMS sensors are not located, will actually be the pointers to the efficacy of the installed sensors of the BAS and therefore can act as re-calibration audit support other than broad basing the IAQ measurements beyond the fixed areas.
It is therefore recommended that the measurement, monitoring, and the validation of the CO2, PM10, PM2.5, Temp., and Humidity levels in the indoor environment of any commercial or public facility/building should now become an intrinsic part of its Planned Preventive Maintenance (PPM) activity in light of the new health and hygiene regime as recommended by leading institutions and public health experts.
Thus managing safe and secure Indoor Air Quality begins with IAQ measurement and monitoring.
Wolfgang Schade 1,2,* , Vladislav Reimer 1,2, Martin Seipenbusch 3 and Ulrike Willer 2 ation: Schade, W.; Reimer, V.; Seipenbusch, M.; Willer, U. Experimental Investigation of Aerosol and CO2 Dispersion for Evaluation of COVID-19 Infection Risk in a Concert Hall. Int. J. Environ. Res. Public Health 2021, 18, 3037. https://doi.org/ and Exhaled CO2 as COVID-19 infection risk proxy for different indoor environments and activities Authors: Z. Peng1 , J. L. Jimenez1*. Affiliations: 1Cooperative Institute for Research in Environmental Sciences and Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA.