Sweet spot suggested for COVID-safer indoor humidity

Embargoed until: Publicly released: 2022-11-16 11:01

International

Photo by Alex Kotliarskyi on Unsplash

We know indoor settings play a big part in COVID-19 spread but we’re yet to learn why spread and severity can differ so much. American researchers dug into data from 121 countries, extrapolating indoor climate conditions based on outdoor weather. They revealed a Goldilocks result: an in-between relative humidity - 40 to 60% - was strongly associated with better COVID outcomes, whereas both lower and higher humidity were linked with worse outbreaks.

Media release

From: The Royal Society

The spread and severity of COVID-19 has been distinctly non-uniform. Seasonality was suggested as a contributor to regional variability, but the relationship between weather and COVID-19 remains unclear. Because humans spend most of their time indoors and because most viral spread occurs indoors, we investigate the hypothesis that indoor climate – particularly relative humidity (RH) – may be the more relevant modulator of epidemic outbreaks. To study this association, we combined population-based COVID-19 statistics and meteorological measurements from 121 countries. We rigorously processed epidemiological data to reduce bias, and developed and directly experimentally validated the estimate of indoor conditions based on outdoor weather data and indoor comfort assumptions. We performed a comprehensive analysis and found robust and systematic relationships between regional outbreaks and indoor RH. In particular, intermediate RH (40%-60%) was robustly associated with better COVID-19 outcomes (vs. RH <40% or >60%). Together, these results suggest that indoor conditions, particularly RH, could possibly modulate the spread and severity of COVID-19 outbreaks

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Research The Royal Society, Web page URL after publication

Journal/
conference: Journal of the Royal Society Interface

Research:Paper

Organisation/s: Harvard University, Massachusetts Institute of Technology, The Institute for Medical Engineering and Science (US)

Funder: This research was made possible thanks to the partial support of MIT Alumni Class fund for the HST.537 class, the MIT Reed & Edgerton Funds, the Richard and Susan Smith Family Foundation, the Canadian Institute of Health Research (CIHR) 2019 Novel Coronavirus (COVID-19) rapid research program and the National Science Foundation. C.A.V. was supported by the National Science Foundation Graduate Research Fellowship under Grant No. 1745302.

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