A wind speed threshold for increased outdoor transmission of coronavirus: an ecological study

  1. Sean A. P. Clouston
  2. Olga Morozova
  3. Jaymie R. Meliker

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Abstract

Background

To examine whether outdoor transmission may contribute to the COVID-19 epidemic, we hypothesized that slower outdoor wind speed is associated with increased risk of transmission when individuals socialize outside.

Methods

Daily COVID-19 incidence reported in Suffolk County, NY, between March 16th and December 31st, 2020, was the outcome. Average wind speed and maximal daily temperature were collated by the National Oceanic and Atmospheric Administration. Negative binomial regression was used to model incidence rates while adjusting for susceptible population size.

Results

Cases were very high in the initial wave but diminished once lockdown procedures were enacted. Most days between May 1st, 2020, and October 24th, 2020, had temperatures 16–28 °C and wind speed diminished slowly over the year and began to increase again in December 2020. Unadjusted and multivariable-adjusted analyses revealed that days with temperatures ranging between 16 and 28 °C where wind speed was < 8.85 km per hour (KPH) had increased COVID-19 incidence (aIRR = 1.45, 95% C.I. = [1.28–1.64], P < 0.001) as compared to days with average wind speed ≥ 8.85 KPH.

Conclusion

Throughout the U.S. epidemic, the role of outdoor shared spaces such as parks and beaches has been a topic of considerable interest. This study suggests that outdoor transmission of COVID-19 may occur by noting that the risk of transmission of COVID-19 in the summer was higher on days with low wind speed. Outdoor use of increased physical distance between individuals, improved air circulation, and use of masks may be helpful in some outdoor environments where airflow is limited.

Article activity feed

  1. Version published to 10.1186/s12879-021-06796-z
  2. Version published to 10.1101/2021.02.05.21251179v2 on medRxiv
  3. ScreenIT

    SciScore for 10.1101/2021.02.05.21251179: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Covariates: We adjusted for number of days since lockdown (March 16th, 2020) and days since reopening began in [COUNTY].
    Covariates
    suggested: None
    Analyses were completed using Stata 16/MP [StataCorp].
    StataCorp
    suggested: (Stata, RRID:SCR_012763)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Limitations: Despite examining a large population (∼1.5 million) where a large number of cases (96,057 between March-December 2020) were identified, this study is limited in examining the experience of a single U.S. county. While this analysis suggests that county residents had fewer cases arising from days where winds were greater, we cannot conclusively state that individuals were protected because of higher windspeed. Our results were strongly influenced by covariates as evidenced by the change in IRR observed in unadjusted versus adjusted models; it is always possible that key confounders were missing from our model. However, our sensitivity analysis examining percent change of new cases on a given day relative to the 8-day backward/forward average case count, attempted to address temporal changes in incidence patterns directly within the outcome variable, and our results were similar. Follow-up research is necessary to determine specifics about exposures including distances that COVID-19 viral particles can travel and reliably infect individuals as well as microclimate differences that may affect specific geographic differences that may moderate these results. To obtain a measure of windspeed for this analysis, we relied on data from a central airport. While this provided highly consistent measures of windspeed for the island, it also provides measures that may not be generalizable to microclimates that can occur in the lea of hills, fenced-in backyards, or forests. Nota...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  4. Version published to 10.1101/2021.02.05.21251179v1 on medRxiv