SARS-CoV-2 test positivity rate in Reno, Nevada: association with PM2.5 during the 2020 wildfire smoke events in the western United States

Abstract

Background Air pollution has been linked to increased susceptibility to SARS-CoV-2. Thus, it has been suggested that wildfire smoke events may exacerbate the COVID-19 pandemic. Objectives Our goal was to examine whether wildfire smoke from the 2020 wildfires in the western United States was associated with an increased rate of SARS-CoV-2 infections in Reno, Nevada. Methods We conducted a time-series analysis using generalized additive models to examine the relationship between the SARS-CoV-2 test positivity rate at a large regional hospital in Reno and ambient PM2.5 from 15 May to 20 Oct 2020. Results We found that a 10 µg/m3 increase in the 7-day average PM2.5 concentration was associated with a 6.3% relative increase in the SARS-CoV-2 test positivity rate, with a 95% confidence interval (CI) of 2.5 to 10.3%. This corresponded to an estimated 17.7% (CI: 14.4–20.1%) increase in the number of cases during the time period most affected by wildfire smoke, from 16 Aug to 10 Oct. Significance Wildfire smoke may have greatly increased the number of COVID-19 cases in Reno. Thus, our results substantiate the role of air pollution in exacerbating the pandemic and can help guide the development of public preparedness policies in areas affected by wildfire smoke, as wildfires are likely to coincide with the COVID-19 pandemic in 2021.

Woodsmoke particle exposure prior to SARS-CoV-2 infection alters antiviral response gene expression in human nasal epithelial cells in a sex-dependent manner

“…During 2020, air quality reached unhealthy and hazardous levels in the western United States due to wildfires, which coincided with the spread of COVID-19. Epidemiological evidence has shown that worsened air quality from PM is associated with increased COVID-19 case rate and case fatality rate around the world ( 31 – 37 , 39 , 40 ). Toxicological studies have indicated that PM exposure affects the host defense response of the airways on viral infection.…”

“…Numerous epidemiological studies from around the world have found correlations between ambient air pollution levels and COVID-19 case number or case fatality rate ( 31 – 35 ). Recently, two studies found positive associations between ambient woodsmoke particles (WSPs) and COVID-19 cases and deaths in the western United States ( 36 , 37 ).…”

Elucidating the role of environmental management of forests, air quality, solid waste and wastewater on the dissemination of SARS-CoV-2

“…Secondary transmission routes are also plausible. For example, air quality can be reduced due to higher levels of pollutants from wildfires and other activities, which have shown to lead to strong impacts upon contracting COVID-19 ( Liu et al, 2020a ; Meo et al, 2020 ; Middleton, 2020 ; Curtis, 2021 ; Dragone et al, 2021 ; Kiser et al, 2021 ; Leifer et al, 2021 ; Setti et al, 2020 b; Zhou et al, 2021 a). Furthermore, natural ventilation for optimal indoor air quality is not sufficient to control the potential spread of SARS-CoV-2 ( Li et al, 2004 ; Meiss et al, 2021a ; WHO, 2021a).…”

Technical note: Use of PM<sub>2.5</sub> to CO ratio as a tracer of wildfire smoke in urban areas

“…To examine this hypothesis, we use data from a monitoring site in Sparks, NV, near Reno, a region that has been heavily influenced by smoke in the past several years due to the large number and extent of California wildfires. Data from this region were recently used to examine the role of high PM2.5 exposure from smoke on COVID-19 incidence (Kiser et al 2021). From the Sparks, NV observations, we develop a quantitative model using a Monte Carlo simulation that provides a range of probabilistic results that can be compared to observations.…”