Does wearing a facemask cause a decline in oxygen saturation in adults over 65?

An article published by Chan, Lee and Hirsch in the Journal of the American Medical Association, October 30, 2020 looked at this vaccine question. 

Participants self-measured peripheral oxygen saturation before, while and after wearing a mask. 

They included individuals aged 65 years or older and excluded those who had co-morbid cardiac or respiratory conditions that could lead to dyspnoea or hypoxia at rest or who were unable to remove the mask without assistance.  

They provided participants with a three layer plain shaped disposable non-medical facemask with ear loops and a portable pulse oximeter.  

The participants were instructed how to self-monitor and asked to record three times 20 minutes apart for one hour before, one hour while and one hour after wearing the mask whilst they were at rest or performing their usual daily activities at home. 

Of the 25 participants, the pooled mean oxygen saturation was 96.1% before, 96.5% while and 96.3% after wearing the mask. 

None of the participants’ oxygen fell below 92% whilst wearing the mask.

In this small study group wearing a three layered non-medical facemask was not associated with a decline in oxygen saturation in older participants.  

This study helps to support the claim that wearing non-medical facemasks in the community setting is safe.

Impact of Mask Wearing on COVID 19 Incidents.
Another abstract by Shacham published as a preprint in Medrxiv looked at the association of county-wide mask ordinances with reductions in daily COVID-19 incidence in the Midwestern region of the United States over 12 weeks.

They found a reduction in case growth to be significant and a reduced infection by race and population density.  

The objective of the study was to assess the impact that a mandatory mask wearing requirement had on the rate of COVID-19 infections by comparing counties with a mandatory policy with those neighbouring counties without a mandatory masking policy.  

Interestingly, they found that those counties with a mandatory mask policy had a daily percent COVID-19 growth rate that was 1.32 times lower or a 32% decrease over those who did not. 

At 12 weeks post mask policy implementation, the average daily case growth amongst those counties without a mandatory mask policy was 2.42% and this was significantly higher than the average daily COVID case, both amongst the mandatory mask wearing counties at 1.36%.  

The data demonstrated that county level mask mandates were associated with a significantly lower instance of COVID-19 case growth over time compared with those neighbouring counties that did not implement a mask mandate. 

Interestingly enough, another medical finding was that following the implementation of the mask policy, this disparity of infection rate by race and population density was no longer significant, suggesting that regional level policies cannot only slow the spread of COVID-19 but simultaneously create a more equal environment.

Facemask and Airborne Transmission in the Hair Salon.
An interesting publication in Toxicology and Industrial Health published October 21, 2020 by Harrichandra and others looked at the estimation of airborne SARS-CoV-2 infection transmission risk in the New York City hair salons.  

The study sort to model airborne infection transmission risk amongst five realistic exposure scenarios using the previously eliminated outdoor air flow rates for 12 New York City male salons.  

They found that the risk of airborne infection transmission across all salons and all exposure scenarios when not wearing facemasks ranged from less than 0.015% to 99.25% with an average airborne infection transmission rate of 24.77%.  However, the wearing of facemasks reduced the airborne infection transmission risk to less than 0.01% and 51.96% depending on the salon.  This gave an average airborne infection transmission risk of 7.3% across all salons. 

Increased outdoor air flow rates in hair salons were generally strongly related with decreased average airborne infection transmission risk.  

They concluded that the results of the study indicated that increased outdoor air flow rates and use of facemasks by both employees and customers would substantially reduce SARS-CoV-2 transmission in New York City hair salons.  

The London General Practice has always encouraged the wearing of facemasks in all settings.  

During the next period of lockdown, The London General Practice will remain open and naturally all safety measures are put in place to ensure that any consultation occurs within a safe environment.

Dr Paul Ettlinger
London General Practice

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