Your alarm shrieks and you hit the snooze button. You have just deposited germs on your alarm clock.

Most of us cringe when strangers cough or sneeze near us in public. “Please don’t make us sick,” we think. But it’s our own hands that are culprits. As we go about our day, our hands pick up other people’s germs and deposit our germs for other people to pick up. What kinds of germs? Mostly the ones that cause colds, flus and diarrhea, but also norovirus, staph, MRSA and more.

Let’s track where the worst microbes are in the course of a day. Our tour guide? Charles Gerba, often called “Dr. Germ,” a microbiologist at the University of Arizona. Here’s what Gerba has found in more than 40 years of looking for germs.

Your home: Let’s start in the closet — seriously. Clothes can harbor salmonella, hepatitis and other viruses. Gerba found those germs and others can survive our laundry efforts because most Americans don’t wash clothes in hot water or use bleach anymore. The solution: Use bleach or the hot cycle if you can. If not, run the dryer for more than 30 minutes, which can kill germs.

Things only get worse when you reach the kitchen for breakfast. Gerba said our kitchens harbor far more pathogens than our bathrooms because of our own germs and those on raw meat and produce. The worst hot spots are the sink, sponge and counters. The solution: Clean your kitchen sink and counter frequently with disposable disinfectant wipes, especially after handling raw meat or produce. Use paper towels, instead of a sponge, to wipe your counters. Run your sponge through the dishwasher or microwave it for one to two minutes to kill germs.

The problems continue as you gather up your belongings before leaving home. If you wash your hands thoroughly and then grab your purse or cellphone, you are probably defeating the purpose. Gerba has swabbed the bottoms of women’s purses and said about a third of them are contaminated with fecal bacteria, probably from being placed on public restroom floors.

Gerba and his team have tested cellphones that contained 100,000 bacteria. And because they are our constant companions, they are uniquely positioned to spread germs. “Viruses are a bit more mobile today than ever before because you’ve got mobile phones,” Gerba said.

The solution: Hang your purse on the bathroom hook rather than placing it on the floor. And never put a purse on your kitchen counter. Wipe your smartphone frequently with an alcohol-free antiseptic wipe. (Alcohol is not good for the screen.)

Your commute: If you take the bus or train to work, you are six times more likely to get sick than if you walk or drive, simply because you are coming into contact with more people and their germs, Gerba said.

The solution: Use hand sanitizer or wash your hands just after exiting public transit.

The workplace: The restrooms have their risks, but they are not the worst germ centers. They’re topped by the elevators. The ground-floor elevator button is like a petri dish of germs because everybody who uses the elevator touches it.

But there’s something even worse — the break room. Coffeepot handles are the hot spot, but the whole area is a concern because, once again, where there are many people, there are many germs. “We found that viruses were spreading between people who had never met,” Gerba said. “We figured maybe the problem was the restroom, but it was really the break room.”

The solution: Wash your hands as soon as you exit the elevator. Encourage your company to have a professional cleaning service swab down the break room. And wash your hands thoroughly after visiting the break room.

Restaurants: Once again, the restaurant restroom is not the biggest problem, probably because it is frequently and professionally cleaned. So think about what everybody touches at a restaurant: the menu. Gerba and his assistants found an average of 185,000 bacteria on menus in one test of restaurants in three states. There are probably about 100 times more bacteria on that menu than on a typical toilet seat, Gerba said.

The solution: Order your food from the menu and then excuse yourself to the not-so-dirty restroom to wash your hands. Or carry hand sanitizer and use a quick squirt before eating.

Grocery stores: Shopping cart handles are the culprit here, but not necessarily because the person who used it before you was sick. Gerba found E. coli bacteria on half of the shopping cart handles he tested. It could have come from a variety of sources, but one of the main suspects is the raw food the users handled while shopping.

Fabric grocery bags also can add to the risk because they provide germs a direct route from the grocery store to your home. Gerba found that about half of reusable grocery bags were also contaminated with E. coli.

The solution: Ask your grocery store what shopping cart sanitation measures it takes and reward stores that have a plan in place. Don’t eat while you shop. Wash or sanitize your hands after shopping. Place reusable grocery bags on the floor rather than the kitchen counter while unloading. Wash your fabric grocery bags with hot water, bleach or both.