NEWS RELEASE October 2020
Efficient Tight Fitting Masks are Needed to Beat COVID
The evidence appearing in the daily alerts in the Coronavirus Technology Solutions shows that
- Most of the transmission is through small aerosols
- Large droplets on the mask’s internal surface become small aerosols
- The typical surgical mask is only half as efficient as a tight fitting high efficiency mask
Small aerosols containing coronavirus are inhaled and exhaled through the periphery of surgical masks. The COVID battle will be won with either N95 masks or improved versions of surgical masks which minimize leakage.
Tight fitting masks are inherently more uncomfortable and require more effort to wear properly than the typical surgical mask. Since the virus travels as easily as perfume or cigarette smoke the tighter the fit the better. There are recent innovations to provide a tighter fit. One is a self-adhesive mask. Others add a peripheral band which is adjustable. This is a solvable problem which will not add much to cost.
An individual should have multiple mask types which he wears as conditions warrant. This can range from N100 down to tight fitting surgical masks. It can include non-valved as well as valved designs.
Much of the time no mask will be required. The mask selection at any point in time should be appropriate to the risk in a specific environment. This risk is indicated by
- New COVID-19 case counts
- Incidence rate (new cases per 100,000 people), and
- New case trajectory (whether the number of new cases is going up, going down, or staying the same over time).
- Indoor and outdoor pollution levels
- Testing Positivity ratios
- Site specific factors such as number of people per ft2. Air changes per hour and efficiency of HVAC systems
Individuals should continually assess risks and wear the appropriate mask for the circumstances. Let’s take an example which is prominent in the news The cost of holding the Supreme Court nomination at the White House in September is estimated at $140 million as a result of coronavirus cases and deaths which will result from this one event.
This amount is based on the eventual deaths of two people and infection of 100 people as attendees pass the virus along to non-attendees. Social distancing would have cut the cases to 50. In addition surgical masks would have reduced the cases by another 25. N95 masks would likely have reduced the cases to five. Even with the N95 masks the risk is unacceptable. When all costs including quality of life are considered it would have been an $8 million cost for one event. This is much less than the $140 million actually generated with no masks or social distancing but still too high a price to pay.
This event was predictably high risk. One metric would be to assume a net positive ratio in excess of 15 as a rating of risk for this event. There are some parts of the country where the risk is well less than 1% if only a small number of local people attend.
The number of cases of an infection for a proposed event can be predicted depending on the risk. In this case we used net positive rate as the indicator and compared results for rates of 1 to 15.
McIlvaine has created a methodology to assess the costs and benefits of various mask decisions. This includes healthcare costs, economic costs and life quality costs. It is then balanced by the benefits of lives saved and cases avoided which has both economic and life quality components. There is a detailed analysis of these costs and benefits for the White House event in the October 7 Coronavirus Technology Solutions alert.
The costs and benefits of various masks along with their availability are analyzed in the High Efficiency Mask Market and Supplier Program.