The sun is coming back out, the temperatures are rising, and the days are getting longer. It can mean only one thing: spring!

For many, this time of the year starts their big cleaning cycle.

If the warm air gets you in the mood to clean, make sure these places are on your cleaning list.

First up is the shower curtain.

A University of Colorado study found shower curtains hold millions of microbes per square inch. When you shower, these microbes can form an aerosol and make you sick.

Next are the salt and pepper shakers.

In one study, researchers from the University of Virginia found cold and flu viruses on the shakers of every person in their study.

Last are those reusable grocery store bags.

One study found only one in six people washes their bags, and another found they can grow bacteria that can cause food poisoning.

Experts say simple changes can make these places cleaner.

Use a fabric shower curtain and pull it all the way closed, add the salt and pepper shakers to your cleaning list, and toss your reusable bags into the washer for a quick rinse.