YOU EAT PIZZA THAT SAT OUT ALL NIGHT
How gross it it? Pizza crust is dry, the sauce is acidic, and pepperoni and sausage are preservative-laden – all things that don’t support bacteria survival, says Fraser. Different story if you got spinach and tomatoes: moisture-rich toppings tend to breed microbes that can gang up and fell you (diarrhoea, vomiting). Best to refrigerate pizza within four hours, before bacteria have the chance to really go wild.
YOU WASH YOUR COFFEE CUP ONCE A WEEK
How gross is it? If you take your brew black, you’re in luck: “Coffee has antimicrobial properties, and it doesn’t contain the nutrients bacteria need to multiply,” says Angela Fraser, a food-safety professor at Clemson University. Nutrients like protein and sugar – which means milk and sweetener. If your lips deposit bacteria that combine with milk residue, you could give birth to millions of germs. Limit the risk: wash the mug at every knock-off time.
YOU USE THE SAME DISHRAG UNTIL IT STINKS
How gross is it? That odour is a telltale sign of a bona fide science experiment. By the time something smells, “it has millions of organisms growing inside,” says Reynolds. (You need only hundreds to cause illness.) That can include E. coli and salmonella. Ideal: throw it in the washer after every use. Since pretty much no one does that, at least spread the rag out to dry. That’ll kill roughly 90 per cent of bacteria, she says.
YOU WEAR OLD GYM CLOTHES
How gross is it? Well, Rocky did it, right? ”Most men have probably reworn sweat-stained shirts without a problem,” says Dr Jason Miller, a dermatologist. You might get minor acne on your chest or arms; worst case, a staph or fungal infection or folliculitis. If you do wear yesterday’s clothes, kill acne-causing bacteria by sudsing up after your session with a body wash that contains benzoyl peroxide.
YOU SLEEP ON DIRTY SHEETS
How gross is it? Many people carry staph bacteria on their skin without it causing trouble. But it could if the germs you naturally shed while you sleep multiply enough, says Kelly Reynolds, director of the Environment, Exposure Science and Risk Assessment Centre at the University of Arizona. Aim to launder sheets weekly, or at least wash your pillowcase, since it’s next to germ entry points (mouth, nose and eyes).
YOU SKIP WASHING YOUR HANDS AFTER PEEING
How gross is it? None of our experts specifically said it’s okay, but it’s not the biggest offence so much as just a really rough look. “It’s unlikely that you’ll pick up a germ while urinating that’s hazardous in the way it can be if you pick up a microscopic particle of stool on your hand when using the toilet,” says Dr William Schaffner, an infectious-disease expert. Washing (with soap and hot water) after sitting is, of course, non-negotiable.
YOU SLEEP ON DIRTY SHEETS
How gross is it? Many people carry staph bacteria on their skin without it causing trouble. But it could if the germs you naturally shed while you sleep multiply enough, says Kelly Reynolds, director of the Environment, Exposure Science and Risk Assessment Centre at the University of Arizona. Aim to launder sheets weekly, or at least wash your pillowcase, since it’s next to germ entry points (mouth, nose and eyes).
YOU TEXT ON THE TOILET
How gross is it? Is this at your home, and do you live alone? If so, fine to keep the conversation going. Not so in a public bathroom, says microbiologist Philip Tierno. Think about it: you touch the door and locks, pick up a virus, then deposit it on your phone while texting. Later, your phone goes up to your mouth and the virus goes in. You need only one measly cell of norovirus to chain you to the toilet (without texting) for up to three days. Keep it in your pocket.