2 research outputs found
Transport of Airborne Particles from an Unobstructed Cough Jet
<div><p>This article presents analytical and experimental results for the velocity distribution and transport of expiratory particles from an artificial cough. The stream-wise penetration distance and velocity field of the cough jet were determined through a combination of dimensionless analysis and experimental techniques. The experiments were conducted in a well-controlled environmental chamber with simplified thermal manikins to simulate human coughs and buoyant thermal plumes, and involved flow visualization, velocity measurements employing high and low velocity hot-wire anemometers, and particle size and concentration measurement. The study analyzed three particle sizes—0.77, 2.5, and 7 μm—to examine the impact of particle size on particle transport in the cough jet region and in the vicinity of a receiver occupant positioned in close proximity to the coughing source. The results indicate that the cough jet has a lower axial velocity but higher span-wise expansion rate than a steady jet with an identical discharge velocity. The particles of three sizes have a similar trajectory when considering the transport in the cough jet region. However, particle concentration distributions of the three size particles show that size is an important factor for particle transport in the vicinity of the receiver occupant where airflow velocity decays to the room background air velocity. Furthermore, the results suggest that a cough jet is able to overcome the buoyant human thermal plume and travel further ahead in the region behind the receiver occupant.</p><p>Copyright 2014 American Association for Aerosol Research</p></div
Emissions from Hydrogen Peroxide Disinfection and Their Interaction with Mask Surfaces
A rise in the disinfection
of spaces occurred as a result of the
COVID-19 pandemic as well as an increase in people wearing facial
coverings. Hydrogen peroxide was among the recommended disinfectants
for use against the virus. Previous studies have investigated the
emissions of hydrogen peroxide associated with the disinfection of
spaces and masks; however, those studies did not focus on the emitted
byproducts from these processes. Here, we simulate the disinfection
of an indoor space with H2O2 while a person
wearing a face mask is present in the space by using an environmental
chamber with a thermal manikin wearing a face mask over its breathing
zone. We injected hydrogen peroxide to disinfect the space and utilized
a chemical ionization mass spectrometer (CIMS) to measure the primary
disinfectant (H2O2) and a Vocus proton transfer
reaction time-of-flight mass spectrometer (Vocus PTR-ToF-MS) to measure
the byproducts from disinfection, comparing concentrations inside
the chamber and behind the mask. Concentrations of the primary disinfectant
and the byproducts inside the chamber and behind the mask remained
elevated above background levels for 2–4 h after disinfection,
indicating the possibility of extended exposure, especially when continuing
to wear the mask. Overall, our results point toward the time-dependent
impact of masks on concentrations of disinfectants and their byproducts
and a need for regular mask change following exposure to high concentrations
of chemical compounds