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Writer's pictureJeannie Collins Beaudin

How do you kill coronaviruses?




We received a delivery the other day…brought it into the kitchen where we keep a box cutter, like we always do. My hubby cut open the tape sealing the top and then we looked at each other. Just a minute… Were we doing this right?

We both took a step back. OK, I said, you open the top flaps. The parcel was shipped over a week ago, so it’s unlikely that there could be any live virus inside, even if it was contaminated when it was packed. I’ll remove the contents with my clean hands. You put the empty box in the garage, then we’ll both wash our hands again. I think that works…

This incident got me thinking. As we start to reopen our communities, we need to pay attention to ways we might be bringing the coronavirus into our homes. We already have the habit of removing our shoes at the door and washing our hands with lots of soap for 20 seconds before we touch anything in the house. I know that if I have worn a mask outside, I need to put it into hot soapy water right away. And I know that soap kills the virus, but I needed to know more.

Going shopping?

What about parcels you bring home from the grocery or pharmacy? Do we need to wipe down every item we bought at the store? Since this is a new situation, there isn’t a solid answer to many of our questions. So, here is where I drift into logic… what I plan to do (besides moving my box cutter closer to the door!).

First, knowing how long the virus “lives” on different surfaces helps. Sources I’ve read mentioned that heat and humidity can also affect how long the virus remains able to cause an infection. Here’s some information I found:

  • Hard, smooth surfaces, like stainless steel or plastic—16 hours or up to 3 days

  • Copper is an exception—only about 4 hours

  • Cardboard (an example of a porous, organic surface)—3 to 4 hours most sources; 24 hours quoted in one source

  • Food—no evidence of people catching the virus through the food itself (cooking kills essentially all organisms)

Since many products are packaged in plastic, I plan to wipe everything down unless I know I won’t touch it again for at least 3 days like, say, those extra 3 giant packages of toilet paper that we all need to stockpile, even though it will last for months… 😊 Just kidding (I’m still working on the package I bought last December!), but you get the idea!

I always wash my fruits and vegetables before preparing, but I think I’ll wash them before I put them in the fridge to keep it clean. Although thorough testing hasn’t been done with the current coronavirus yet, there is some suggestion that refrigeration might extend the life of the virus. Rinsing with plain tap water is recommended for fruits and vegetables, as soap and detergents can seep into their porous surfaces and are not intended to be eaten.

After unpacking my groceries, I’ll disinfect the counter where unwashed items had been placed and (of course!) wash my hands. Next thought: what’s a good disinfectant to use?

What solutions should we use to disinfect?

Health Canada has a list of disinfectants that are effective against the coronavirus. Although many are industrial cleaners listed by letter/number code names, there we a few that I recognized:

  • Isopropyl alcohol 70%

  • Household bleach, diluted to 0.12%

- Check the label for bleach strength (can be 2-10%). Dilute as directed for

the strength of your bleach…

-- 2%--15ml (3 tsp) per 240ml (1 cup) of water

-- 4%--7.5ml (1.5 tsp) per 240ml (1 cup) of water

-- 6-7%--5ml (1 tsp) per 240ml (1 cup) of water

-- 8-10%--3.5ml (3/4 tsp) per 240ml (1 cup) of water

-- Solution is effective for 24 hours, once diluted

-- See reference below for more information on using bleach as a

disinfectant

  • Hydrogen Peroxide 0.5%

-- Pharmacies sell hydrogen peroxide 3%. This would be diluted: 1 part peroxide with 5 parts of water to make 0.5% (e.g. 1 tablespoon

peroxide mixed with 5 tablespoonsful of water)

  • A few commercial cleaners listed on Health Canada’s website:

-- Clorox Kitchen Cleaner and Disinfectant or Clorox Wipes

-- Disinfectant Fantastik All Purpose Cleaner

-- Eco Multi-Purpose Disinfectant Spray

-- Lysol Multi-Surface Disinfectant Spray or Wipes

-- I’ve got a package of these at my front door for doorknobs

and small packages going in or out

-- 3M Surface Disinfectant Spray

-- Many more—check the reference “Hard -surface disinfectants”

below

Temperatures above 56C (132F) will also kill the coronavirus, but these temperatures will cause scalding and burns, so be careful! However, this tells us that cooking destroys the virus and suggests we should do laundry in hot water if we think our clothing is contaminated (although the virus is believed to only live a few hours on cloth). Use extra caution if handling clothing that could still be carrying live viruses.

Items to be careful with when out and about, are those with smooth surfaces, and those touched by a lot of people (like door handles, faucets, computer mice/keyboards, key pads on debit machines/self-checkouts, toilet handles, latex gloves—yours or others). As a rule, indoor surfaces are riskier than outdoor ones, as the UV rays in sunlight can kill viruses. Think about your phone, too, if you use it while out (nice smooth surfaces!). See the references below for a great video on how to clean your phone. And droplets (that could contain viruses) linger for more time in still air than in moving air, for example, wind outside, or air conditioning/fans inside.

What about disposable gloves?

Gloves are good to wear when cleaning (if only to protect your hands!) and should be discarded afterward. Wearing gloves in public to try to protect against the virus can give a false sense of security. Gloves can become contaminated as soon as you touch something and viruses live longer on their smooth surfaces, creating the problem of disposing of them safely. Bare hands, however, can be sanitized by washing or using hand sanitizer.

You don’t catch the virus through the skin on your hands, so gloves don’t really give you any added protection. Gloved hands can still transmit virus if they become contaminated and you touch your face while wearing them. Medical workers have a strict procedure for removing gloves to avoid infecting themselves (turning them inside out by touching only the cuff and disposing of them immediately).

A last word about masks…

I’ve written about masks already, but just a final word about why opinions have changed regarding whether everyone should wear a mask in public until there is no risk of a second wave of COVID-19 infection… As I looked at the evidence for and against wearing a cloth mask in public (since we don’t have enough medical masks) I found a study done in 14 hospitals in Vietnam in 2015 (one of very few that have been done) that concluded cloth masks are completely useless and possibly harmful.

It didn’t take long to discover the study had a couple of serious flaws… Usually a control group is used to create a baseline of what would happen if there was “no intervention” (or no mask in this case). It turns out that over 99% of the “control” group, with which the cloth masks were compared, wore medical masks (which are known to be superior to cloth masks). This made it falsely look like the cloth mask was worse than wearing no mask at all! The other point that wasn’t obvious in the original write-up of the study, was that it was sponsored by the giant mask manufacturer, 3M, increasing the risk of bias in the study... incentive to conclude that everyone should buy masks and never trust a reusable cloth one!

A reanalysis done this year as hospitals were running out of masks, took into account that less than 1% of the control group did not wear medical masks. They suggested that cloth masks may have been as much as 50 to 70% effective in the 2015 study. Other comments also note that no information was given about the cloth masks, such as the material used, number of layers, etc. so a well-made mask made from 2 layers of tightly woven or knitted cotton fabric that fits the face snugly, could make a significant difference, especially if it is designed to hold an additional filter.

So far in North America, New York and Los Angeles county have mandated that everyone wear masks when in public to reduce the chance of viral spread and a second wave of COVID-19 infection. Unlike Asian countries, we’re not used to wearing masks and will need to adapt to the idea. As one writer in the Czech Republic commented: At first, we thought those wearing masks were weird; but within just a few days, those NOT wearing a mask were the ones who were weird… Remember that, because cloth masks are believed to be most effective at preventing you from potentially giving an infection to someone else, masks work best to prevent an epidemic when everyone wears one when they can’t be physically separated, especially since the virus can be spread by those who don’t know they have it.

But enough about the coronavirus for a while…

We’ve been inundated with information about COVID-19 for several weeks now and, although I’m sure there’s still plenty to learn as we move forward, it’s time for a little variety in my blog! I’m looking for new topics to write about. Is there a health issue you’ve been wondering about? Send me a comment or question…

References:

Coronavirus Resource Center—Harvard Health Publishing

Hard-surface disinfectants and hand sanitizers (COVID-19) – Canada.ca l

Coronavirus: How to clean your smartphone safely—BBC

A cluster randomised trial of cloth masks compared with medical masks in healthcare workers--BMJ Open journal

Comments on cloth mask study--BMJ Open journal


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