Back in the days when I had an office job, my colleagues would gather around the snack machine every afternoon and kill time talking about things that had nothing to do with work. One day, the conversation took a turn to the unexpected. The subject was how to clean behind the refrigerator. I remember being stupefied because at that time, I had no idea one was supposed to clean behind the refrigerator at all and I had never done so.

Since then, my domestic IQ has increased incrementally, but occasionally a cleaning question arises that leaves me stumped, and surveys indicate that many share my confusion. In fact, even the experts disagree about things like how often we should change our sheets, wash our towels, launder jeans, and shampoo rugs. These are important issues because neglecting good cleaning hygiene can lead to allergies, infections, and other health challenges.

Here are some starter guidelines that might help you establish reasonable and healthy cleaning routines for a few random things you regularly use:

1. Under and Behind Appliances. Never cleaned behind your refrigerator (or stove)? The happy news is that you’re in good company. A comment thread on the home décor website Houzz asked readers for their behind-appliance cleaning schedules, and among the 135 comments were remarks like, “Is there a behind-the-fridge”? And “Oh, Lordie, what a question!”¹ http://www.houzz.com/discussions/747267/how-often-do-you-clean-under-or-behind-your-fridge Some did say they managed the job several times a year, a few bragged of bi-monthly cleansings, but many admitted they only did it when they had to move—at which time the horror of accumulated dust, gunk, pet hair and critter poop shocked and disgusted them.And that’s the bad news. Just because it’s uncommon to regularly clean behind appliances doesn’t mean it shouldn’t be done. If ever there was a place for dust to gather and cockroaches to nest, behind the fridge and stove are top of the list. Cleaning behind and under appliances will decrease allergens (including cockroach excrement, which is an allergen) and even toxins accumulated in dust in the air.
2. Inside out Outside the Fridge. It does little good to clean behind the fridge if the inside is ripe with crawling science projects. To avoid foodborne illnesses as well as contamination with mold and the general yuck factor, you should discard spoiled food items weekly and wash down all the shelves and surfaces inside and outside the fridge with baking soda solution or a mild natural cleanser. If your fridge has water and ice dispensers, it’s important to clean them at least once a month since mold and yeast can grow in the damp environment. Experts suggest using vinegar and hydrogen peroxide in the spouts to disinfect thoroughly.
3. Towels. An informal survey of 500 people conducted by Business Insider found that half of the respondents washed their towels weekly, while another 17 percent did so once every few weeks.² Calderone, Julia. “People don’t wash their bath towels enough, and it’s disgusting.” 29 December 2015. Business Insider. 16 November 2017. http://www.businessinsider.com/how-often-wash-bath-towel-survey-monkey-poll-2015-12 Fewer than 30 percent washed towels twice a week or more often, and yet, according to experts, every two to three days is the magic number for good health.Towels are particularly vulnerable to spreading disease since bacteria and fungi thrive in damp environments, and your towel remains damp after you use it, especially if the weather is hot and humid. Unfortunately, bathing doesn’t fully remove the various secretions and abundant bacteria living on your skin, Experts say there’s still plenty of microbial life left to rub off on the towel, even after you’ve scrubbed with soap and water.³ Laliberte, Marissa. “This is how often you should REALLY be washing your bath towels—and what happens when you don’t.” Readers Digest. 16 November 2017. http://www.rd.com/home/cleaning-organizing/washing-bath-towels-often/ “It keeps building up as you use the towel again day after day,” according to Dr. Chuck Gerba of the University of Arizona. In fact, Dr. Gerba conducted a study that found used towels have 1000 times more coliform bacteria than new ones. Another study conducted by NSF International found residue of yeast, mold, bacteria, e. Coli, and coliform, even on towels used only once, with amounts increasing exponentially with each day of use. The damper the towels remain, the faster and denser the growth.Even so, you don’t need to go fanatical and wash towels daily. In fact, exposure to small amounts of bacteria helps to build up immunity—a few days of consecutive use probably will do no harm except possibly exacerbating acne or skin conditions. But the real problems start when you keep towels for a week or more, because by then you’ve got build-up of significant levels of yeast, mold, and bacteria.

   (Note: many of the bacteria living on your skin are actually beneficial and protect against their more harmful cousins. So, while washing towels regularly is important, over-washing your skin may be counter-productive.

4. Sheets and Mattress Cover. The thing about sheets is that they accrue your shedding skin along with the fungi and bacteria residing on it, as well as ambient pollen and dust mites, which feed on the skin you shed. Experts vary on how often sheets should be laundered, with some insisting weekly washings are a must and others saying twice a month will suffice. Less frequent than every two weeks, though, is a no-no. Your personal frequency should depend on whether you sleep naked (direct skin contact necessitates more washing), if you’ve been hot and sweaty at night, or if you’ve shared the bed with a pet or an amorous partner.  In addition to clean sheets, it’s a good idea to use a mattress cover and wash it every few months.
5. Mattresses. Those dust mites on your sheets can bore through to your mattress, where they find an environment that allows them to reproduce without restraint. They live out their mite lives inside your mattress, where they eventually die, pooping twice their body weight daily along the way. Because their excrement contains a chemical that can trigger allergic reactions, it’s extremely important to clean the bed itself once in a while.Experts suggest that you should vacuum the mattress at least twice a year, then spot clean any stains and sprinkle the entire mattress with baking soda to deodorize. Let the baking soda sit for at least an hour— more hours will do a better job—and if you can expose the mattress to the sun, even better, as that will help the baking soda to penetrate. Then vacuum again and slip the cleaned mattress cover back on.
6. Pillows, obviously, should be covered with pillowcases, but experts say a simple pillowcase isn’t enough. Instead, you should get pillow protectors that are hypoallergenic and antimicrobial, and then put the pillowcase on top of the protector.⁴ Malone, Aibhe. “PSA: Wash Your Damn Pillows, People.” 8 October 2016. Buzzfeed. 17 November 2017. http://www.buzzfeed.com/ailbhemalone/how-often-you-really-need-to-wash-your-pillow-according-to-s?utm_term=.imW5MYLaW#.nrOZKOxoV The pillow protectors should be washed every few weeks and the pillows themselves at least a few times a year.
7. Jeans. If you’ve been a laggard in the washing towels and vacuuming-your-mattress departments, here’s a place where you can shine. The CEO of Levi’s, Chip Burgh, suggests never washing your jeans because it degrades the fabric and wastes water.⁵ Green, Dennis. “How often should you wash your jeans?” 18 March 2016. Business Insider. 27 November 2017. http://www.businessinsider.com/how-often-you-should-wash-jeans-2016-3 Spot clean them, he says. Other sources suggest washing after you wear the pants five or six times.⁶ Challis, Carla. “How often should you wash your bra, jeans and pyjamas?” 22 November 2017. BT. 27 November 2017. http://home.bt.com/lifestyle/house-home/cleaning/how-often-should-you-wash-your-bra-jeans-and-pyjamas-11363965794946 Yes, skin rubs off and microbes accumulate, but apparently, the experts aren’t worried that you’ll suffer ill effects. Wisdom dictates, though, that the stink factor should rule. If the pants smell–or try and walk away by themselves–wash them, and for goodness sake, if you don’t wear underwear, wash them after every use.