A novel negative pressure isolation device reduces aerosol exposure: A randomized controlled trial

Background and aim The COVID-19 pandemic has led to a proliferation of intubation barriers designed to protect healthcare workers from infection. We developed the Suction-Assisted Local Aerosol Containment Chamber (SLACC) and tested it in the operating room. The primary objectives were to determine the ease and safety of airway management with SLACC, and to measure its efficacy of aerosol containment to determine if it significantly reduces exposure to health care workers. Methods In this randomized clinical trial, adult patients scheduled to undergo elective surgery with general endotracheal anesthesia were screened and informed consent obtained from those willing to participate. Patients were randomized to airway management either with or without the SLACC device. Patients inhaled nebulized saline before and during anesthesia induction to simulate the size and concentration of particles seen with severe symptomatic SARS-CoV-2 infection. Results 79 patients were enrolled and randomized. Particle number concentration (PNC) at the patients' and healthcare workers' locations were measured and compared between the SLACC vs. control groups during airway management. Ease and success of tracheal intubation were recorded for each patient. All intubations were successful and time to intubation was similar between the two groups. Healthcare workers were exposed to significantly lower particle number concentrations (#/cm3) during airway management when SLACC was utilized vs. control. The particle count outside SLACC was reduced by 97% compared to that inside the device. Conclusions The SLACC device does not interfere with airway management and significantly reduces healthcare worker exposure to aerosolized particles during airway management.

Long-Term Exposure to PM2.5, Facemask Mandates, Stay Home Orders and COVID-19 Incidence in the United States.

Long-term PM2.5 exposure might predispose populations to SARS-CoV-2 infection and intervention policies might interrupt SARS-CoV-2 transmission and reduce the risk of COVID-19. We conducted an ecologic study across the United States, using county-level COVID-19 incidence up to 12 September 2020, to represent the first two surges in the U.S., annual average of PM2.5 between 2000 and 2016 and state-level facemask mandates and stay home orders. We fit negative binomial models to assess COVID-19 incidence in association with PM2.5 and policies. Stratified analyses by facemask policy and stay home policy were also performed. Each 1-µg/m3 increase in annual average concentration of PM2.5 exposure was associated with 7.56% (95% CI: 3.76%, 11.49%) increase in COVID-19 risk. Facemask mandates and stay home policies were inversely associated with COVID-19 with adjusted RRs of 0.8466 (95% CI: 0.7598, 0.9432) and 0.9193 (95% CI: 0.8021, 1.0537), respectively. The associations between PM2.5 and COVID-19 were consistent among counties with or without preventive policies. Our study added evidence that long-term PM2.5 exposure increased the risk of COVID-19 during each surge and cumulatively as of 12 September 2020, in the United States. Although both state-level implementation of facemask mandates and stay home orders were effective in preventing the spread of COVID-19, no clear effect modification was observed regarding long-term exposure to PM2.5 on the risk of COVID-19.

Modeling the impact of COVID-19 on air quality in southern California: implications for future control policies

In response to the coronavirus disease of 2019 (COVID-19), California issued statewide stay-at-home orders, bringing about abrupt and dramatic reductions in air pollutant emissions. This crisis offers us an unprecedented opportunity to evaluate the effectiveness of emission reductions in terms of air quality. Here we use the Weather Research and Forecasting model with Chemistry (WRF-Chem) in combination with surface observations to study the impact of the COVID-19 lockdown measures on air quality in southern California. Based on activity level statistics and satellite observations, we estimate the sectoral emission changes during the lockdown. Due to the reduced emissions, the population-weighted concentrations of fine particulate matter (PM2.5) decrease by 15 % in southern California. The emission reductions contribute 68 % of the PM2.5 concentration decrease before and after the lockdown, while meteorology variations contribute the remaining 32 %. Among all chemical compositions, the PM2.5 concentration decrease due to emission reductions is dominated by nitrate and primary components. For O3 concentrations, the emission reductions cause a decrease in rural areas but an increase in urban areas;the increase can be offset by a 70 % emission reduction in anthropogenic volatile organic compounds (VOCs). These findings suggest that a strengthened control on primary PM2.5 emissions and a well-balanced control on nitrogen oxides and VOC emissions are needed to effectively and sustainably alleviate PM2.5 and O3 pollution in southern California.

Impacts of COVID-19 response actions on air quality in China

An outbreak of the novel coronavirus (COVID-19) was first reported in Wuhan, Hubei Province, China in December 2019. In late January 2020, the Chinese government implemented strict quarantine measures across Hubei Province and other parts of the country to limit the transmission of COVID-19. An effect of these quarantine measures was the reduction in economic activity and associated emissions that contribute to air pollution. In this study, we quantify the spatial extent and magnitude of changes in air pollution concentrations across China by comparing complementary satellite, ground-based, and modeled data from the first two months of 2019 and 2020. We find a 48% reduction in satellite-derived average fine particulate matter (PM2.5) concentrations in eastern China during a three-week period after the Lunar New Year (LNY) in 2020 compared to 2019, which follows significant declines in the pre-LNY period. We also observe a 49% and 11% decline in post-LNY satellite tropospheric column concentrations of nitrogen dioxide (NO2) and sulfur dioxide (SO2). These satellite-based results are in general agreement with data collected from ground monitoring stations across the country, which show a decline in post-LNY PM2.5, NO2, and SO2 concentrations. Our modeling analysis suggests that these observed air quality improvements are driven primarily by the reduction in NO2 emissions, which indicate reductions in transportation and industrial pollution sources during COVID-19, but unfavorable meteorological conditions weaken the role of emissions reduction. Finally, we estimate a reduction by 5%, 14%, and 18% of days in the post-LNY period for 2020 that exceed national PM2.5 air quality targets for the entire country, eastern China, and Hubei Province. As more information becomes available on population characteristics and air pollution exposure patterns, this analysis can be extended to quantify human health related impacts to sudden changes in air pollution in China and other locations around the world.