NAMBA March 2021 Web

PROPWASH 4 Safety Corner Spring 2021 By Lohring Miller NAMBA Safety Chairman Along with the rest of the country model boaters face a significant safety risk – Covid 19. This winter saw a huge surge in cases that is now slowing. There are precautions that can help maintain this trend. First, let’s cover what we know about this virus. Covid is a very contagious, airborne virus. Unlike the cold and flu, it is contagious even if you don’t have symptoms. This transmission can be stopped with simple precautions. Dentists have been required to take these precautions for decades. Our procedures can spray fluids from the mouth all over. However, there have been no outbreaks tied to dental offices even though our protective measures weren’t necessarily designed to stop the transmission of airborne diseases. Our first line of defense was surgical masks. Now we wear N95 masks that are more closely fitted as well as face shields for some procedures. The effectiveness of various masks is shown in the chart below. My office has installed room size HEPA filtration units in patient treatment rooms. As an aside, these masks and filtration units were very effective against this summer’s heavy smoke from the serious local forest fires. We also disinfect surfaces after each patient and wear gloves and gowns. I have always washed my hands between patients. We either sterilize or discard any items we use to treat a patient. These latter precautions are important for many diseases, but are not as critical for Covid. There are very few cases where Covid has been transmitted by contact with contaminated surfaces. A further example of the effectiveness of surgical masks is a case in Colorado. There, two hair stylists with Covid but wearing masks treated a group of clients. None of their clients developed Covid. Data from schools also supports the effectiveness of masks and social distancing. The CDC believes there have been almost no disease transmissions between students in the lower grades where students can be depended on to wear masks. Most cases came from teachers and staff. An outline of these recommendations is at https:// www.cdc.gov/coronavirus/2019-ncov/downloads/community/ schools-childcare/Operational-Strategy-for-K-12-Schools- through-Phased-Mitigation.pdf Masks are not all equal. The first issue is proper coverage and fit. Masks need to fit tightly, covering the mouth and nose. If your glasses are fogging, the fit over the nose is not good enough. Only N95 masks without an exhalation valve are de- signed so nearly all the breath goes through the mask. Other masks leak around the sides to some degree. However, you are relatively safe when facing the mask wearer. Filtration of the mask material is the other issue. An article in Science Advances 02 Sep 2020 tested a number of masks. Look at the pictures and chart for the results. Mask Effectiveness & Material Unmasked Cough Plume Travel March 2021 Another test of mask effectiveness involved measuring the droplet plume from a simulated cough. The table shows the results.