By Dr. Anthony Policastro

I received a call from a reader asking me about using ultraviolet light to cleanse COVID-19 from surfaces.

The following day President Trump asked a similar question. The question is a valid one. However, as with all things there are pros and cons.

The first thing to address is ultraviolet light. Not all ultraviolet light is the same.

UV-A comes from the sun. It makes up most of the ultraviolet light to which we are exposed.

UV-A  penetrates deep into the skin. It is thought to be responsible for about 80 percent of skin aging. That includes wrinkles and age spots.

There is evidence that it can cause some skin cancers.

The second type is UV-B. It can damage the DNA in the skin. It causes sunburn. It causes most skin cancers. Both UV-A and UV-B can be blocked by skin creams.

The third type is UV-C. It usually gets filtered out by the ozone layer. So not much gets through the atmosphere. UV-C can destroy genetic material. This includes the genetic material in viruses.

The UV-C that we use for sterilization has been around for many years. It was actually discovered in 1878. It is used for sterilizing hospital equipment. It is used on airplanes. It is used to sterilize drinking water.

The question is whether it is effective against COVID-19. We know it kills other coronaviruses so it is safe to assume that it also kills COVID-19. Based on this assumption, China is already using it.

They have garages that sterilize buses. They have UV-C robots that clean hospital floors at night. Banks use it to sterilize money.

Unfortunately, the demand has outstripped supply. Manufacturers have empty warehouses. This means that any large scale worldwide use is not yet possible. There is not enough of it.

As with any good thing, there can be too much of that good thing. Sunburn occurs after a few seconds of exposure. That means special training is necessary to properly use it.

Some companies sell UVC light bulbs. They may be used to disinfect certain areas of the house.

However, when you go online, the site says: “Warning: please make sure there are no people, animals or plants in the room, since skins and eyes can not be exposed to the UV light for a long time.”

Therefore, proper use requires significant safety precautions.

There are also UVC cleaning devices. They are aimed at cleaning cell phones. There is plenty of evidence that cell phones are dirty. There is little evidence that infectious organisms last on them long enough to be transmitted.

The best rule is when you take your cell phone out, wash your hands after using it and before eating. If you do decide to buy a device, remember not to look at the UV light.

The newest development is called Far-UVC light. It has a shorter wavelength and effectively kills bacteria.

Far-UVC light has not harmed human cells in the lab. However, that is about as far as we have gotten in testing it.

Ultraviolet light is not a far fetched concept. However, there are significant safety concerns associated with it. In addition, it continues to be in short supply.

Like anything else, there is much more to the story.

COVID-19 update

The daily increase in cases for the U.S. remains in the 25,000 to 40,000 new cases every day, so the curve remains flat.

With the relaxation of restrictions, we would not expect to see a change for about 10 days due to the long incubation period of the virus.

Just like it took 10 days for the restrictions to slow it down, it will be at least 10 days before can tell if there is a significant uptick in cases if we are going to see one.

As far as local numbers go, Sussex County continues to be a hot spot. Nationally there has been about one case for every 238 people. New Castle County has a similar number at one case for 228 people.  In Sussex County there has been one case for about every 54 people.