A research led by The University of Texas at Austin is adding clarity on weather’s role in Covid-19 infection, with a new study finding that temperature and humidity do not play a significant role in coronavirus spread.
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This means whether it’s hot or cold outside, the transmission of Covid-19 from one person to the next depends almost entirely on human behaviour.
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“The effect of weather is low and other features such as mobility have more impact than the weather. In terms of relative importance, the weather is one of the last parameters,” said Dev Niyogi, a professor at UT Austin’s Jackson School of Geosciences and Cockrell School of Engineering who led the research.
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The research was published in the International Journal of Environmental Research and Public Health.
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The study defined weather as “equivalent air temperature,” which combines temperature and humidity into a single value. The scientists then analysed how this value tracked with coronavirus spread in different areas from March to July 2020, with their scale ranging from U.S. states and counties to countries, regions and the world at large.
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At the county and state scale, the researchers also investigated the relationship between coronavirus infection and human behaviour, using cellphone data to study travel habits. The study examined human behaviour in a general sense and did not attempt to connect it to how the weather may have influenced it. At each scale, the researchers adjusted their analyses so that population differences did not skew results.
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Across scales, the scientists found that the weather had nearly no influence. When it was compared with other factors using a statistical metric that breaks down the relative contribution of each factor toward a particular outcome, the weather’s relative importance at the county scale was less than 3 per cent, with no indication that a specific type of weather promoted spread over another.
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