bias (overcoming)

Recent descriptive literature suggests that debiasing, although not easy or standardized, is feasible. It starts with an awareness that bias is omnipresent and pervades many aspects of clinical sciences. Recognition and willingness to change are of utmost importance. The first step in bias minimization is an awareness of susceptibility. Some debiasing strategies have been studied, and when consistently utilized, could mitigate bias

Debiasing strategies that have been studied include considering the opposite, by actively seeking information that counters the initial hypothesis. In addition, it is helpful to review data and form opinions in the absence of outcome information, and not allow referral sources to overframe the case.

thinking (critically)

Critical thinking is the analysis of facts to form a judgment. The subject is complex; several different definitions exist, which generally include the rational, skeptical, and unbiased analysis or evaluation of factual evidence. Critical thinking is self-directed, self-disciplined, self-monitored, and self-corrective thinking. It presupposes assent to rigorous standards of excellence and mindful command of their use. It entails effective communication and problem-solving abilities as well as a commitment to overcome native egocentrism and sociocentrism.

fit and finish

The results show that 4 out of 7 participants were unable to achieve a proper fit from any of the tested N95 respirators.

This study also found that without proper fit, the value of high filtration material significantly decreases. Participants were seen to achieve similar protection from a fabric face covering as from a KN95 respirator, whose material should perform similarly to an N95 respirator. Indeed, our results indicated that surgical masks, poorly fit KN95 respirators, and basic fabric face coverings offered similar levels of protection to the wearer.

This implies significant reduction as in a separate study:

The protective efficiencies were 33.3%, 11.3%, and 6.1% for the surgical, bandana, and dust masks, respectively.

Phthat has implications

Face masks - A potential source of phthalate exposure for human

…the face mask is usually made from polymers and phthalates are widely-used additives into the polymers, the face mask could be a potential source of phthalate exposure to humans.

In this study, twelve phthalates were determined in 56 mask samples collected from different countries. The phthalates were detected in all the samples with total levels ranging from 115 ng/g to 37,700 ng/g. Estimated daily intakes (EDIs) of the phthalates from the masks ranged from 3.71 to 639 ng/kg-bw/day, and the EDIs of the phthalates from masks for toddlers were approximately 4-5 times higher than those for adults.

…This review of the recent literature suggests that early life and adult exposure to phthalates may contribute to adverse cardiovascular health, with changes in BP and risk of atherosclerosis. With this evidence, it is important to inform the population about these risks and to promote public health. In order to do that, sources and routes of phthalate exposure must be of public awareness so they can be greatly reduced, especially in vulnerable populations, pregnant women, children, and the elderly.

a thought problem

Science indicates droplets evaporate and become aerosol at a rate dependent on initial size and environmental factors.

Which has greater aerosol dispersement?

1) droplets dispersed onto a fabric at an approximate height of 6 feet, circulated and evaporated by manual transportation and convection?

2) droplets dispersed into the air and subject to normal gravity and air circulation?

-rws

While the largest expiratory droplets quickly hit the ground, the airborne lifetime of droplets smaller than approximately 150 µm is mainly defined by their evaporation characteristics. The airborne lifetime of droplets with an initial diameter of less than 50 µm is mainly determined by their equilibrium size. Most importantly, these small droplets may stay airborne for more than one hour. It could be demonstrated that the experimentally determined ratio between initial and equilibrium diameter may affect the airborne droplet lifetime considerably.

distance, location, filtration and airflow

Overall, rapid mixing, dilution and removal limit exposure risk for aerosol contaminants at 1 and 3 μm in all tested seat sections of the Boeing 767 and Boeing 777 wide body aircraft. The maximum exposure in a nearby seat of 0.4614% of a characterized release, equates to a 99.54% reduction from an aerosolized source of contamination such as SARS-CoV-2. Looking further across the approximately 40 seats nearby the simulated infected patient there is average reduction maximum in the aft section of the 777, with exposure risk of 0.0124%, representing a 99.99% reduction. Importantly, this represents a single infectious point source, not a scenario with multiple infected passengers. Testing focused on aerosol transport and smaller 1 to 3 μm particulate.

…It was observed that the location of the release source was critical in affecting both the tracer concentration levels and its transport inside the aircraft cabin. When the release source was placed close to the exhaust, the overall tracer concentration was lower. In contrast, when the release source was located at the central seat, almost all of the seats in the front and back rows had a larger exposure risk. Both the transient tracer distributions from the contour maps and the C[F.sub.N] data showed the tracer gas (simulating the airborne pollutants) was laterally spread in the space before being flushed out of the cabin if the release source was centrally located. From this finding, one possible way to decrease the exposure risk of infectious diseases would be to move the release source from the center to the sides or from the back to the front seats. In This could be employed at some emergent situations, for example, an outbreak of the toxic chemicals or the airborne infectious diseases occurred, or the degradation products of the engine oil or hydraulic fluids accidentally entered the passenger cabin.