Exposure to ultrafine particles while walking or bicycling during COVID-19 closures: A repeated measures study in Copenhagen, Denmark

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Ultrafine particles (UFP; particulatematter

From late-March to mid-July 2020, UFP was repeatedly measured while walking or bicycling, capturing local COVID-19 closure (`Phase 0') and subsequent phased re-opening (`Phase 1', '2', '2.1' & '3'). A DiSCmini continuouslymeasured particle number concentration (PNC) in thewalker/bicyclist's breathing zone. PNCwhilewalking or bicycling was compared across phased re-openings, and the effect of ambient temperature, wind speed and direction was determined using regression models.

Approximately 40 repeated 20-minute walking and bicycling laps were made over 4 months during societal reopening phases related to the COVID-19 pandemic (late-March to mid-July 2020) in Copenhagen. Highest median PNC exposure of both walking ( 13,170 pt/cm(3), standard deviation (SD): 3560 pt/cm(3)) and bicycling (21,477 pt/cm(3), SD: 8964) was seen during societal closures (Phase 0) and decreased to 5367 pt/cm(3) (SD: 2949) and 8714 pt/cm(3) (SD: 4309) in Phase 3 of re-opening. These reductions in PNC were mainly explained by meteorological conditions, with most of the deviation explained by wind speed (14-22%) and temperature (10-13%). Highest PNC was observed along major roads and intersections.

In conclusion, we observed decreases in UFP exposure while walking and bicycling during societal re-opening phases related to the COVID-19 pandemic, due largely to meteorological factors (e.g., wind speed and temperature) and seasonal variations in UFP levels. (C) 2021 The Authors. Published by Elsevier B.V.

OriginalsprogEngelsk
Artikelnummer148301
TidsskriftScience of the Total Environment
Vol/bind791
Antal sider9
ISSN0048-9697
DOI
StatusUdgivet - 2021

ID: 276610263