MANY people are complaining about why it is only the Philippines, of all countries, that require people to wear both face masks and face shields. Those who complain claim that face shields are unnecessary, may not actually help contain transmission and can even do harm.

I have heard people complain about being disoriented and worse, about losing their sense of balance. I have read quite a few posts on social media of people actually bumping their heads or worse, falling over and tripping.

One time I posted a selfie of me wearing a face mask and a face shield, and a friend now living in Australia called my attention to the fact that I may survive the coronavirus disease of 2019 (Covid-19), but I am definitely killing myself of carbon dioxide poisoning.

I do get it. Wearing a face mask is enough of an inconvenience. To wear face shields on top adds another burden. It can be terribly hot and humid in the Philippines and wearing plastic face shields over a masked face can seriously create discomfort. My shield gets foggy, not only when I perspire but every time I step out of an air-conditioned room or car. And when it drizzles, shields, because they do not have wipers, can become instant wearable obstructions.

The list could go on.

But at the end of the day, what matters most is whether they provide an added layer of protection against Covid-19. And this is the main beef of shield-bashers. They argue that shields do not really reduce exposure to the virus.

What added fuel to the fire was Manila Mayor Francisco Domagoso, aka Isko Moreno, vocally coming out against the wearing of face shields in his city, to the point of questioning the scientific basis of the face shield policy, alleging that it is merely based on imagination. This was countered by Malacañang, with Palace spokesman Harry Roque Jr. citing that there is scientific evidence to show that the wearing of face shields on top of a face mask can help further reduce the transmission of the SARS-CoV-2 virus that causes Covid-19.

And thus, the issue became partisan, with the Duterte haters jumping on Roque.

This column has criticized Roque on many occasions. But on this one, it would be in his defense.

There is no reason for Isko Moreno to dismiss as zero any scientific evidence about the use of face shields. After all, they are worn by frontline medical workers when they deal directly with Covid-19 patients. Thus, it is safe to assume that there is some basis to wearing face shields as an added layer of protection against Covid-19.

Science is not just about empirical studies but also about logical thinking. Since the virus causing Covid-19 is transmitted as aerosolized droplets that circulate in the air, any physical barrier that covers any facial body orifice, such as the eyes, nose and mouth, would logically help reduce the possibility of transmission.

This is precisely why plastic barriers are being erected between tellers or cashiers and customers in banks and in stores, or between customers in restaurants. Plastic barriers are also seen in offices and even in the session halls of courts and in Congress. If one questions the scientific basis for the wearing of shields, then to be consistent these same people, including Mayor Isko Moreno, should also question these plastic barriers. After all, face shields are nothing but wearable versions of these plastic barriers.

But more importantly, it is not entirely true that there is zero evidence about the ability of face shields to reduce transmission. A study conducted by Emmanuel Bhaskar and Santhanam Arun in India revealed that without face shields, 12 workers or 19 percent of the 62 health workers who visited homes where 222 persons eventually tested positive for Covid-19 also got infected. After wearing face shields, none of the 50 workers sent to homes where 2,682 persons subsequently tested positive for Covid-19 were infected.

In contrast, those who criticize the effectiveness of face shields cite the study conducted by the team headed by Hussein Salimnia. But as pointed out by Dr. Edsel Maurice Salvaña, the study may not be the best evidence to use against face shields in relation to Covid-19, considering that the study was done on bacterial infection (and Covid-19 is caused by a virus that is a lot smaller than and behave differently from a bacteria), and unlike the study conducted by Bhaskar and Arun, it was conducted as a laboratory simulation and not in the real world. Besides, the study even found out that using both a face shield and a cloth face mask yields better protection than wearing only a cloth face mask and is comparable to wearing a surgical mask. Thus, and particularly when people wear cloth face masks, the additional wearing of face shields yield extra protection.

Another issue raised by Moreno is that the mandatory use of face shields only adds a financial burden for people. This may be a valid argument as face shield prices have drastically gone down, with some being sold at very minimal prices, and are reusable.

Those who oppose the use of face shields point out that despite the fact that we are the only country that requires the wearing of face shields, Covid cases here remain high. This is a claim coming from people who question the scientific basis of the effectiveness of face shields, now committing an equally unscientific allegation that just because our cases are high face shields probably do not work. They discount the possibility that it may also be true that our situation could have been worse had we not required the wearing of face shields in public places. This is particularly true when one considers the possibility that many transmissions are happening in workplaces and in homes where people rarely wear face shields or even masks.