The next time you back away from someone who sneezes, consider that the person spreading the most germs in the room just might be…yourself.
That’s the word from researchers at UC Berkeley and Yale University. Their study, just published in the journal Indoor Air, found that each of us adds 37 million bacteria to the air for every hour we stay in a room, many of which will linger long after we leave, mingling with dust and germs from new and former occupants.
Floor dust harbored most of the bacteria that study subjects breathed. Americans are believed to spend more than 90 percent of their time indoors, so it’s no surprise that most infectious diseases are spread in a closed space, rather than outdoors. But before you invest in a hazmat suit to wear to your next party, here are more myths and surprising facts about germs:
Myth, says Dr. Charles Gerba, author of The Germ Freak’s Guide to Outwitting Colds and Flu. In a recent report for the TV show 20/20, Gerba found that the floor and sanitary napkin machine were the most germ-filled places in ABC News’s own bathrooms.
The sink, door handle and toilet seat—spots that most people expect to be contaminated—were the cleanest, with the least number of bacteria per square inch.
Fact: Microwaving a sponge will kill all of its bacteria, but so will cleaning it in the dishwasher. The U.S. Department of Agriculture’s Agricultural Research Scientists (ARS) tested sponges that had been soaked for 48 hours in a ground beef solution and other germy substances to find the best way to eliminate germs. Soaking sponges in lemon juice, deionized water or a 10 percent bleach solution only killed between 37 and 87 percent of the bacteria, while cleaning them in the microwave or dishwasher both killed more than 99 percent of germs. But if you want to sterilize your sponge in the microwave, beware: a dry sponge can catch fire. Be sure to thoroughly soak your sponge before you nuke it.
Myth. Dogs carry more bacteria in their mouths than humans, but their germs aren’t the type that would infect us or make us sick. Still, experts recommend that small children and people with weak immune systems should avoid contact with dog and cat saliva.
Fact. And the type of dip also matters. A 2009 study published in the Journal of Food Safety showed that saliva on chips does contaminate chip dip as a result of double-dipping. However, researchers conducted the experiments on three types of dip—chocolate, cheese and salsa—and initially the salsa tested higher in harmful bacteria. However, after two hours at room temperature, the salsa showed fewer germs than the chocolate or cheese dips.
Myth. Bacteria become resistant when they are exposed to antibiotics, but hand sanitizers are alcohol-based, and they contain no antibiotics. Therefore, the sanitizers play no part in creating antibiotic-resistant superbugs, reports a recent review of hand sanitizers published in Clinical Microbiology Reviews.
Myth: Food that spends even two seconds on the floor can pick up salmonella or E. coli bacteria. A high school student tested the theory, first contaminating a floor with E. coli, then dropping cookies and gummy bears onto the surface. Her analysis found that items left on the floor for two seconds or more contained significant levels of E. coli. We all hate to waste food, but if your baby drops food on the floor, toss it out. When a pacifier hits the floor, reach for a clean one until the contaminated “binky” can be washed with soap and hot water.
Mostly fact: Chlorine and other pool-cleaning chemicals kill bacteria that cause illnesses—but not all germs are eliminated immediately. Chlorine does kill most harmful bacteria in minutes, but a few, such as the diarrhea-causing cryptosporidium, can take days to clear away. Swimmers can never be sure when a public pool was last treated, so it’s best to play it safe and avoid getting water in your mouth.
Fact: A four-year study by University of Arizona’s Environmental Research Lab found that grocery carts ranked as #3 in the most germ-ridden public surfaces, after playground equipment and armrests in public transportation. What’s more, another analysis found fecal bacteria in 72 percent of the shopping carts tested.
And there are plenty of other places in the grocery where bacteria hide, such as the irrigation systems used to wet down the produce. Germs can breed wherever you see standing water, such as the asparagus containers, so be sure to wash your veggies—and your hands--when you get home.
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