UNDER THE MICROSCOPE Dr. Raymund W. Lo Recently, the IATF announced it was looking into lifting the face shield requirement in outdoor spaces. Face shields were allowed to be removed in cinemas. Well and good, but is it really necessary to wear face shields in public at all? Let’s examine the issue in greater detail. The face shield requirement was instituted in the latter half of 2020 when hygiene theater was at its height. Plastic/acrylic dividers blossomed forth in most establishments and in public transport. Even motorcycle riders were required to out up “pillion” barriers, again of plastic between rider and passenger. Even hospitals got into the act. I had taken to wearing closed fitting goggles to protect my eyes early on, which did a better job of keeping my eyes from virus exposure than a face shield. But no, management mandated that everyone wear face shields. My protest fell on deaf ears. Now, all the plastic barriers are practically gone including on jeeps, buses and motorcycles. Why? Because they were found to be ineffective and in some instances were more conducive to catching the virus than keeping it away. Does the same apply to face shields? Let’s look at the evidence, both medical and engineering. Some experts have referred to certain journals that offered evidence of efficacy in reducing viral exposure. So, I checked out these journals to see what “solid” evidence there was for face shield use in public. In theory, the aim is to protect mucus membranes (eyes, nose and mouth) from exposure to the SARS-CoV-2 virus which can enter the body through these portals and attach to the ACE receptors. The face mask, especially the surgical, N95 and KN95 types do a great job protecting the nose and mouth. Eye protection comes in several forms: goggles, shields or safety glasses. According to the Princeton University Environment Health Safety, eye protection should: 1. Protect against specific workplace hazards 2. Fit properly and be reasonably comfortable to wear, 3. Provide unrestricted vision and movement, 4. Durable and cleanable, 5. Allow unrestricted functioning of any other required PPE. Both the Occupational Safety and Health Administration (OSHA) and Centers for Disease Control recommend goggles as the preferred method of protection (I was right all along). It cited the lack of good peripheral facial seal and that little is known about the effectiveness of face shields in preventing transmission of viral respiratory diseases (Safety of Goggles versus Face Shields in the COVID-19 Era (AAO.org). Indeed, the most common and cheapest face shield locally available which is probably most in use has gaps over the eyebrows, the sides and under the chin, which leaves the wearer susceptible to exposure to small aerosolized droplets swirling around in the air. A University of the Philippines wind engineer recently said face shields may actually increase risk of exposure to Covid-19 instead of helping prevent spread of the disease. He said, “Face shields tend to create a negative pressure region so it acts as a suction and sucks what is in the air, most likely including the virus.” Although the WHO states that face shields can be used as an eye protection against respiratory droplets, in conjunction with face masks, specifically medical masks, a study at the Wayne State University states that “Plastic Face Shields add Little Protection to Face Masks”. According to Dr. Teena Chopra, “The role of the face shields in preventing transmission is not supported, and if transmission via the eyes is felt to be a significant factor, such as with health care workers and dentists and dental technicians, goggles might provide better protection than a face shield.” A review in the Lancet by Chu et al (June 1, 2020) found no robust randomized trials to better inform the evidence of interventions, including eye protection. In their discussion, “These data suggest that wearing face masks protects people (both health care workers and the general public) against infection by these coronaviruses, and that eye protection could confer additional benefit. The “could” hardly gives a sense of certainty to eye protection, again taking note that the term encompasses both face shield and goggles. In summary, the medical evidence for the efficacy of the face shield against respiratory virus infection is at best doubtful and of low certainty, aside from being bunched together with goggles which give better protection and may well be responsible for whatever slim margin of eye protection there is. Let’s now turn to the possible bad effects of wearing face shields. Aside from possibly enhancing virus infection by air convection, the poor optical quality of the plastic used in face shields has been reported to be responsible for some accidents, violating the major tenet of medicine: First, do no harm. There is the ecological damage from disposal of large numbers of plastic face shields that add to the degradation of our environment and production of microplastics. The Philippines has been tagged as one of the major plastic waste producers and the disposal of hundreds of thousands, even millions will surely bring us to the top tier of plastic polluters. Think of the economic harm to our poor countrymen who can barely afford three meals a day but still have to shell out ₱15-20 for a useless face shield. Multiply that by millions of face shields required. Isn’t this cruel and unusual punishment? How much more suffering can the Filipino stand? Adding insult to injury, we are made to wear an object that has been determined to be the subject of corruption and overpricing. What a painful reminder to have something perched on your nose that may well have been paid for by your taxes and still have to buy it over again. Job had not been this patient. We can only pray “Deliver us from this evil, amen!”