*COVID 19: My Returning Home Decontamination Checklist*
30 June 2020
I've been learning about UV (Ultraviolet) and ozone since before COVID19 but I've gotten serious about using them for disinfection.
Hospitals, food processing plants and laboratories have been using UVC and ozone for many years to disinfect. UVC lamps kill up to 99.9% of viruses, bacteria and mold. It's very effective but must be used correctly to keep people, plants and pets safe.
When choosing a UVC light, look for one in the germicidal wavelength of 185 or 254 nanometers. This is the light that renders organisms sterile. The killing efficiency of UVC is the product of time and intensity. High intensities for a short period or low intensities for a long period are equally effective.
When comparing prices of UVC lamps notice their life expectancy. Both of mine are advertised as good for 17,000 hours of use, with only 20% decrease in output over that use. Another thing to look for is the wattage of the lamp. High wattage means a higher intensity of UC. As a rule of thumb a 15-watt lamp will disinfect about 100 square feet; a 30-watt lamp will cover approximately 200 square feet. Just remember, the killing power decreases as the distance from the lamps increases. Larger areas may be disinfected in sections or may require the use of multiple lamps. UVC is a light and as such it travels in a straight line. That means it's easy to miss germs/virus that linger round a corner, in a crevice or under a table. Disinfection is only effective when the light comes in direct contact with the surface. It you have a large space with a lot of junk sitting around, you may need to strategically place several lamps around the room. You can easily test where the UV will contact by using a flashlight and noticing where the light lands on surfaces and where the shadows are. Also, UV takes time to kill. One light I have requires the UV to be in contact with the microbe for 60 seconds to deactivate it. Another requires 30 minutes.
As for precautions: long-term exposure of UV light to plastics will shorten it's life. Just think about how plastic deteriorates after sitting in the bright sun all summer. Plant life will be damaged by direct, or reflected, UV rays. Colors in fabrics will be faded from prolonged exposure to ultraviolet rays. Also, direct exposure to UV light can cause temporary skin redness and eye irritation, but it doesn't cause skin cancer or cataracts.
If you have a lot of shaded areas that the UVC light cannot reach you might consider a UV/ozone "germicidal" bulb. Ozone is a gas. It's good for getting behind and under objects or in places you can't see. Don't breathe the ozone gas, it does irritate the lungs and can make you sick. It is nearly instant at disrupting an organism's DNA; meaning the organism dies quickly.
Over the past months I've accumulated an air purifier, a UV/ozone germicidal bulb and an ozone laundry system. I like that my units are portable and can be used in different spaces.
I have the germicidal bulb below; it's both UV and ozone. For disinfecting stuff and places, I'm bettin' it's the best of both worlds. At 25w it takes about 30 minutes to disinfect a 200SF room. But I don't want to be in the room while it's on. The ozone smell is highly offensive.
I have the ozone laundry system below. I launder with no detergent and in cold water. Not only does ozone kill bacteria and virus but it also attacks bed bugs, fleas and ticks.
I also plumbed an inline valve so that I can divert ozonated water from my washing machine into a spray bottle or a garden sprayer. I've been happy using the spray bottle for kitchen counters, light switches and door knobs. It does not harm fabric and leaves no residue. I can shower with ozone-ated water. I like rinsing with that rather than bleach water after I've been out and about. Just remember that ozone is not stable. It's only ozone for about 30 minutes. Ozone-water must be used immediately. If you want to mix up something to keep by the door, bleach water is more sustainable.
Microlux Air Purifier:
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