Air quality in housing through CO2 as a health risk indicator

Resumen

Air quality can be evaluated based on the CO₂ concentration. The theoretical reference limit is ~350 ppm in air, but due to the effects of anthropogenic sources, it has reached 410 ppm. In times of the COVID-19 pandemic, bedrooms are a typical indoor environment for isolation, where the ventilation rate has a significant effect on the transmission of the SARS-CoV-2 virus. Exhaled air has the potential to emit viruses through Flügge/Wells droplets, which affect the health of people living in a house. The reported limit for CO₂ indoors is 1,000 ppm in air. In this
study, CO₂ concentrations were measured outdoors, indoors (houses), in human exhalation with/without a mask. The measurements were obtained with a Testo 535 probe. The outdoor CO₂ concentration reached up to 640 ppm indicating unacceptable quality, and the indoor ranged between 902-1,101 ppm for home, exceeding the standard value for good air quality. The average concentration of exhaled CO₂ ranged from 23,780 to 30,093 ppm. CO₂ concentration was reduced when exhaling with a KN-95 or standard 3-layer surgical masks. Therefore, they can stop the passage of Flügge/Wells droplets that potentially contain SARS-CoV-2 when a person is sick and decrease the risk of  coronavirus disease transmission.
Therefore, the objective of this work was to determine the air quality by measuring the CO₂ concentration outdoors; inside houses and during breathing without a mask, with a KN-95 mask or a standard 3-layer surgical mask as an indicator of risk in the transmission of the SARS-CoV-2 virus.