CIVID-19 Groceries, Mail, Cleaning, Practical Information.

Ultraviolet Light Kills Viruses and Bacteria and it is “free”.


But we do not know whether exposing clothing and other articles to outdoor light will kill COVID-19. So washing machine + Dryer is the best advice unless you have a medically approved UV sanitizing device. Soap and hot/warm water works.


Viruses are not really “alive” in the sense that bacteria, parasites, algae are alive but they can cause great harm. For the rest of this discussion “alive” and “dead” in reference to harmful viruses will refer to “probably infectious/viable” and “not probably infectious/viable”.

A Stanford professor and viral researcher posted how he goes about grocery shopping and engaging in other tasks. His comments are worth considering.

You can find them here.

These are some of his salient points.

A recently published paper in the NEJM studied viable virus duration on various surfaces.

Copper – no viable COVID-19 after 4 hours
Cardboard – no viable COVID-19 after 24 hours
Stainless steel – no viable COVID-19 after 48 hours
Plastic – no viable COVID-19 after 72 hours
Not tested – glass, rubber, clothing, carpeting, tile, wood, stone, paper, and foods. No documented food transmission, cooked or uncooked, has been reported to my knowledge.

From Dr. Utz:

It is important to understand several things about these numbers:
–    The virus decay over time is “exponential”. 
o    This means that half of the virus on stainless steel is dead after 5.6 hours, and half of virus on plastic is dead after 6.8hours.
o    So for stainless steel at 24 hours, only about 5% is still alive. For plastic at 24 hours only about 10% is still alive. That’s not much. With hand washing and not touching eyes, ears or nose, my personal interpretation for typical exposure out in the community is that there is not much to worry about.
–    The studies were done under very controlled conditions – room temperature and 40% humidity.
–    There is no way to know what happens in fridges and freezers. 
–    It is thought that warmer weather and sunlight make it harder for viruses like this to survive.
–    The data on cardboard was “noisy”, that is was more variable, and should be interpreted with caution.

Here is Professor Utz’s practical tips.

–    Assume public surfaces could be contaminated. Wipe down surfaces, like door handles, gas pumps, and keyboards. Use Purell, wash hands frequently, and don’t touch your eyes, nose or mouth unless you have washed your hands. Gloves are really not needed in the community. Healthcare workers on the front lines need gloves way more than any of us. Our risks are extremely low if we follow the guidance.
–    Assume the virus can be aerosolized (the length of time in air is still being studied and is very hard to estimate given all of the variables in the community). Minimizing time in closed spaces with others in the public, and staying 6 feet apart is good practice and reduces this risk greatly. Personally, I only used an N95 mask once last week in a massively overcrowded grocery store. The mask I used was from my garage that I have used for years when sanding my decks. Again, healthcare workers on the front lines need masks way more than any of us. Moreover, unless properly trained, the masks don’t work and can even increase your risk if in a high-risk environment like a hospital ICU (but not uncrowded places like stores – these are low risk places). The same with gloves – most people don’t know how to properly put them on and take them off, potentially increasing the risk of getting the virus to aerosolize. MGH sent out an email this morning about this topic. They described how to use masks if on the front lines, and how to clean them in the event there is a shortage (a worrisome message). The take home point is that we don’t need masks, but our caregivers and first responders do. Donate unused masks if asked. The MGH video is here:
–    There have not been any documented cases of food transmission. We should assume for now that we should be washing fresh food as usual, and preparing food hygienically.
–    Based on available data, I personally am doing the following (again, this is not a recommendation, just a description of my approach):
o    At grocery stores. I try to get in and out as quickly as I can. I used to go to our local store almost daily, but now go every 4-5 days to buy for several households. This means going in with a list of only what is needed. I keep my 6 foot distancing. I don’t wear gloves or mask. I go alone and if I had kids I’d not bring them in the store (yes, I still am seeing this happen – parents should STOP). If the store is crowded, I come back when it is not crowded. I pay with a credit card and not cash. After shopping I take the cart out to the car and then load into my own canvas bags myself. (Note some stores in our area are now banning customers bringing in their own bags). I bring the groceries home and unload them on the porch (that is, I don’t bring the bags in the house and I don’t place them on my kitchen floor like I used to do). I deliver to some at risk relatives and friends and just leave the bags on the front porch and text them to grab them. When I am done unpacking groceries, I leave the bags out in the sun and consider them OK to use again when I shop again 4-5 days later.
o    At restaurants. I am now starting to get take out again regularly. The restaurants clearly need the business. I distance myself, pay with a credit card, carry to my car, unload like I do for groceries, and I transfer food to plates (ie I don’t eat from containers). 
o    Delivery. Many people are using delivery services which is one way to cut exposure at grocery stores and restaurants completely, and to provide income to drivers. 
o    When returning home from work or these rare outings.
§    We have always had a “no shoe rule” in our home because we work in hospitals and have no idea what is on the floor. 
§    For those who do wear shoes in the house – based on the data in the NEJM paper, it sees unlikely that enough virus would land on the floor, then get transmitted to shoes, then somehow make it to the mouth, eyes or nose and cause an infection. Since carpeting has not been tested in studies yet, there is no way to know for sure. 
§    For days where we are in the clinics or in a crowded grocery store only, we change clothes and shower when we get home out of an abundance of caution. How long the virus can remain in clothing, and whether it is transmissible, is not known and is hard to study. Follow the CDC guidelines:
§    We wash hands regularly, and particularly after unloading new purchases. And before, during and after preparing and eating food.
§    We wipe down cell phones, and we use speaker phone wherever possible so we don’t get the cell phone close to our face.
§    And to end with some levity, we don’t bite our nails, apply cosmetics while pumping gas (I observed this last week, I kid you not), pick our noses, or pick other people’s noses.

Some information on disinfectants from Michael Lin PhD-MD:

• Hand sanitizer is just 60-70% ethanol with moisturizers.
• The ethanol you want to use is 95% non-denatured ethanol
– 95% denatured ethanol has toxic additives to prevent drinking (will have a health hazard logo).
– 100%/dehydrated/absolute/anhydrous ethanol has benzene, also toxic, from the purification process.
• Isopropanol can be substituted for ethanol, but just takes longer to evaporate
– 60-70% isopropanol is just as effective as 60-70% ethanol as a disinfectant.
– 99-100% isopropanol (rubbing alcohol) can be purchased by the consumer as a cleaning and disinfecting agent.
• The moisturizer can be aloe vera gel (available in drugstores) or glycerol (a common lab reagent, and an ingredient in moisturizers and makeup).
Lin Lab recipe: Mix two parts 95% non-denatured ethanol or 99-100% isopropanol with 1 part aloe vera gel or 90-100% glycerol. That’s it!

Hygiene recommendations from Dr. Lin:

• Don’t shake hands and stay 6 ft away from people outside your household – these are easy.
• But ”wash your hands often” and “don’t touch your face” are confusing without context – how often is often? Why can’t I touch my face? Should I ask someone to scratch my itchy nose for me? Shouldn’t I also worry about what I’m touching, not just my hands? If so, what cleaning solutions should I use?
• I’ll provide some details. I treat hands and objects similarly, and I am pretty strict:
– To protect yourself, sanitize your hands right before eating and right after touching things touched by others.
– To protect others, use clean hands to touch others’ things or when handling things to others.
– Sanitize objects you get, and only give out sanitized objects. For example, I have hand sanitizer open and ready to clean my credit card right after I get them back from cashiers, before I put it back in my wallet.
– Outside your house, sanitize smooth surfaces you will touch directly with your hands (e.g. tables and chair edges, wherever you put your phone and computer).
– I keep track of whether hands/objects are clean. As long as they have not encountered unknown/dirty things after their last cleaning, they don’t need to be recleaned. This is why I suggest immediate sanitation of hands after touching unknown/dirty things, so you can resume using your clean things without worry.
– You can open doors with your body or foot, and use paper towels to handle faucets or knobs.
– Create clean zones – your house, your office (if you’re allowed to work), your car.
– Sanitization can be done by soap and water (hands) or hand sanitizer (hands or objects) or Windex (objects).
– “Disinfectants” like bleach or quaternary amines are for large areas for which soap (due to the need to rinse) or alcohol (due to fumes, expense) are not practical. If you can use soap or alcohol, you don’t need them.
– Finally, if your hands are clean, you can touch your face! But remember to sanitize them before you touch other people’s stuff.

Because this information is practical I have created a separate page on this website to include it’s contents.


Eat clean, drink filtered water, love, laugh, exercise outdoors in a greenspace, get some morning sunlight, block the blue light before bed, engage in meaningful work, find a sense of purpose, spend time with those you love, AND sleep well tonight.

Doctor Bob

1 thought on “CIVID-19 Groceries, Mail, Cleaning, Practical Information.

  1. Pingback: COVID-19, WHY IT IS DIFFERENT, EXPLAINED BY AN IMMUNOLOGIST | Practical Evolutionary Health

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