Observations and experiments indicate a significant role of humidity in the spread of acute respiratory viral infections (ARVI), including influenza and COVID-19. Meanwhile, counter-examples are given, allegedly refuting this regularity. Mention is made of wet Texas and COVID-19 outbreaks in summer 2020. Obviously, such cases need to be investigated for anomalies, and not reject the theory based on intuition or life experience alone.
The intuitive example of wet Texas misses a number of important details. Summers are long and Texas is big: Houston is on the coast and El Paso is in the desert. The very concept of "humid climate" is poorly defined. As a rule, this is an average comparison of relative humidity with drier regions, but for the spread of ARVI, the (presumably) absolute humidity is important , that is, the amount of water vapor in the air.
In general, the wet Texas speculation suffers from what is known as an environmental fallacy â the misuse of summary data to draw conclusions about the properties of individual cases or groups. It is interesting to look at the situation on a smaller scale, in dynamics in specific settlements.
Data on the number of COVID-19 infections are published on the website of the Texas Department of Health. Historical weather data for individual cities can be taken from the OpenWeatherMap website . For $ 10, the service provides weather data in one city for the last 40 years with an accuracy of one hour. These data include: temperature, relative humidity, atmospheric pressure. To calculate the absolute humidity, it is also necessary to know the pressure P s of saturated water vapor. The formula for calculating the pressure (in Pascals) of saturated water vapor at a given temperature t (-30 ° C <t <35 ° C) is given in Bolton D. The Computation of Equivalent Potential Temperature, Mon. Wea. Rev., 1980, 108 (7): 1046-1053 (formula 10):
, , /3, :
R=8,314 /(*) â , Îŧ=18.02 / â , T= t + 273,15 â , 0 < hr < 1 â , h â . :
| T, K | h, % | Ī, /3, | |
|---|---|---|---|
| 01.08.2020 00:00:00 | 305,86 | 62 | 21,77 |
| 01.08.2020 01:00:00 | 304,13 | 66 | 21,13 |
| 01.08.2020 02:00:00 | 302,94 | 70 | 21,01 |
| 01.08.2020 03:00:00 | 301,89 | 78 | 22,11 |
| 01.08.2020 04:00:00 | 301,44 | 83 | 22,95 |
| 01.08.2020 05:00:00 | 300,88 | 88 | 23,59 |
| 01.08.2020 06:00:00 | 300,58 | 88 | 23,21 |
| 01.08.2020 07:00:00 | 300,48 | 88 | 23,08 |
| 01.08.2020 08:00:00 | 300,25 | 88 | 22,79 |
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03.07.2020 . , .
The graphs are built in the LibreOffice spreadsheet processor . The source file is available.
Houston.
Dallas.
Beksar.
El Paso.