The science behind cleaning

If you've been avoiding spring cleaning since the start of the season, you're not alone. For most of us, the thought of steaming our carpets or cleaning out the crisper section of the refrigerator makes us want to crawl under the covers and wish for winter. Almost. Since we can all use some extra motivation to get our rubber gloves on, we've rounded up the leading expert advice about how often you should clean everything and, more important, why. Turns out, your home is harboring more bacteria than a public trash can. Motivated yet?

Frequency: Every week

For years, the conventional wisdom was that cooking food in a microwave oven was a great way to kill bacteria and make it safe to eat. New research suggests that might be a myth, so keeping your microwave splash-free is crucial. We recommend wiping it down once a week, then doing a deep cleaning twice a month. Try this handy concoction: Mix half a cup of water with half a cup of white vinegar in a heat-safe dish. Microwave it on high until the window steams up, then wipe the interior with a sponge. Easy.

Frequency: Every week

The toilet has a reputation as one of the dirtiest areas of a bathroom, but according to new research, it's got nothing on your bathtub. Elizabeth Scoot, co-director of the Center for Hygiene and Health in Home and Community at Simmons College in Boston, compared the bacteria she found on tubs to trash cans. Scoot found skin infection-causing bacteria in 26 percent of tubs tested, compared with just 6 percent of garbage cans. Yes, your bathtub is officially grubbier than the trash. The verdict: Clean your bathtub as often as your toilet — ideally every week.

Frequency: Every one to two weeks

Surprisingly, fresh findings suggest your bed linen isn't as dirty as you might think. "We've done research that showed that you don't get as much exposure to dust mites [when] in bed as we once thought," said Euan Tovey, head of the Allergen Research Group at the Woolcock Institute of Medical Research. He says you're subjected to dust mites whenever you're moving, not just when you're in your bed. But before you forgo washing your sheets, take note: Results vary depending on your sleeping routine. If you don't shower after work or snooze in the buff, opt to wash bed linens every week or two in hot water.

Brace yourselves: Scientists say salad drawers contain 750 times the safe level of bacteria, making them one of the main places to clean regularly. Don't wait for a spring-cleaning reminder; this part of your home deserves monthly attention.

Frequency: Every week

A massive 70 percent of Americans eat lunch at their desk, making computer keyboards a hotbed for bacteria. One study found that keyboards harbor five times the bacteria found on a toilet seat, but 10 percent of people never clean them. Set aside time every Friday to give your desk a once-over with disinfectant spray. Pay attention to the mouse, too, and use a cotton swab dipped in alcohol to clean between keys.

Frequency: Every three months

Pillowcase protectors can help shield your bed from dust mites and daily grime, but don't forget to wash the pillow itself; every three months is ideal, according to Robin Wilson, an interior designer who specializes in allergy-free homes. Depending on your allergies, pillows should be replaced as often as every six months, although he admits most people are fine to keep them for three years.

We hate to break it to you, but vacuuming doesn't count as carpet cleaning. If you don't regularly steam your floors, research suggests it could be harming your health. "Indoor air quality can be eight to 10 times worse than outdoor air quality. If you don't clean your flooring, clean your drapes and let air inside regularly," said Wilson. That's not all. Another study suggests your carpet could contain up to 200,000 bacteria per square inch. Have we convinced you yet? Opt for a professional steam cleaning every six to 12 months, or more frequently if you have a pet.

Frequency: Every two months

You might regularly wash your linens, but what about your mattress? Carolyn Forte of the Good Housekeeping Institute says mattress pads need to be washed every two months, and that you get bonus points for cleaning your mattress while the protector is in the wash. Her cleaning hack: Sprinkle the mattress with baking soda to absorb odor, vacuum it, then spray the mattress with Lysol to kill bacteria.

Frequency: Every day

According to experts, countertops are dirtiest near the sink area because people tend to use sponges contaminated with food. Be sure to wipe surfaces daily, and swap out your kitchen sponges and washcloths every week.