![]() To derive the SARS-CoV-2 aerosol concentration in indoor air, we assume well-mixed air ( Figure 1). Whether a single CO 2 concentration ensures a low COVID-19 infection risk in all common indoor environments remains an open question but is also critical for effective CO 2-based mass risk monitoring. (19,20) In particular, only a single CO 2 threshold was recommended in each of these proposed guidelines. A few guideline limit concentrations have been proposed, but without a solid and quantitative basis. (17,18) However, the CO 2 level corresponding to a given COVID-19 infection risk is largely unknown. Because the background (ambient) CO 2 level is almost stable and indoor excess CO 2 is usually only from human exhalation, measurements of indoor CO 2 concentrations by low-cost CO 2 sensors can often be good indicators of infection risk and suitable for mass deployment. Indoor CO 2 was suggested as an indicator of ventilation of indoor spaces in the 19th century, (15) and more recently as a practical proxy of respiratory infectious disease transmission risk, (16) as pathogen-containing aerosols and CO 2 are co-exhaled by those infected ( Figure 1). Although large uncertainties, mainly from virus exhalation rates, are still associated with infection risk estimates, our study provides more specific and practical recommendations for low-cost CO 2-based indoor infection risk monitoring.ĭirect measurements of virus-containing aerosols are extremely difficult and slow. We show that the CO 2 level corresponding to a given absolute infection risk varies by >2 orders of magnitude for different environments and activities. The relative infection risk in a given environment scales with excess CO 2 level, and thus, keeping CO 2 as low as feasible in a space allows optimization of the protection provided by ventilation. We derive analytical expressions of CO 2-based risk proxies and apply them to various typical indoor environments. Indoor CO 2 measurements by low-cost sensors hold promise for mass monitoring of indoor aerosol transmission risk for COVID-19 and other respiratory diseases. CO 2 is co-exhaled with aerosols containing SARS-CoV-2 by COVID-19-infected people and can be used as a proxy of SARS-CoV-2 concentrations indoors.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |