Scientists recently tested surfaces in the homes of people with colds. They found that commonly touched areas, such as refrigerator doors and handles, were positive for cold germs about 40 percent of the time.

All three of the salt and pepper shakers they tested were contaminated, as were 6 out of 18 doorknobs, 8 out of 14 refrigerator handles, 3 out of 13 light switches, 6 out of 10 remote controls, 8 out of 10 bathroom faucets, 4 out of 7 phones, and 3 out of 4 dishwasher handles.

When the researchers deliberately contaminated surfaces with participants' mucus and then tested to see whether rhinovirus stuck to their fingers, they found that more than half of the participants got the virus on their fingertips 48 hours after the mucus was smeared.