Cleaning with bleach might increase your chance of getting COPD. How worried should you be?

Disinfectants aren’t good for you, but they’re also not the main cause of lung problems.

You shouldn’t breathe in bleach. If you could avoid ever coming in contact with it again, you’d be healthier. But the same is true of high fructose corn syrup and alcohol. We’d all probably be better off if we didn’t drink or eat candy, and yet we persist. Bleach doesn’t give us the pleasant buzz that sugar and ethanol do, but most of us will inhale its fumes at some point—and many have no choice but to do so daily as an occupational hazard. It’s one of the most common industrial disinfecting agents. So how much is too much?

“Raises your risk by 32 percent” sounds like a lot. That’s the number most news outlets are citing, which is the maximum amount that researchers recently found disinfectants could increase a person’s chances of getting COPD. Chronic obstructive pulmonary disorder, as it’s less commonly known, is a lung disease caused by irritation to the airways that can block airflow. If it’s left untreated or is exacerbated by another problem, it can be fatal. That number—32 percent—is accurate, and the implications are troubling. But it’s important to understand it in context.

Standard household use of bleach is not the problem

These numbers come from something called the Nurses Health Study II, long-term project out of Harvard on how lifestyle affects disease risk. Basically, they took a big cohort of nurses several decades ago, asked them a ton of questions about their lives, and then continued to follow up with them periodically. They asked the same questions and performed the same tests, and over time researchers have been able to find associations between particular lifestyle factors and particular diseases. It’s important to remember, though, that they’re just associations. And that the subjects are all nurses. Occupation might not be relevant for studies about diet or exercise, but it’s important when we’re looking at exposure.

Bleach is a powerful disinfectant that health professionals encounter at higher levels than the average person. So when scientists say that in this study, people who cleaned with bleach at least once a week were 32 percent more likely to get COPD, remember that those nurses were already around a lot more disinfectant fumes than, say, an office worker would be.

If you work in a space that doesn’t commonly use bleach, these results apply to you less. Unless, of course, you clean with bleach a lot at home. We’re probably not talking about scrubbing the shower once a week. But if you’re cleaning your whole bathroom with bleach every day, you might want to think about your habits (though again, it’s important to remember that there’s no way of knowing exactly how much bleach these nurses were cumulative exposed to). There’s limited information on how domestic use of bleach affects your lungs, but given that a high-exposure job raises your risk by a maximum of one third, home use is not likely to be a big risk factor for most people.

If, on the other hand, you work as a custodian—or in a space where disinfectants are common—you should pay a little more attention. Thirty-two percent is not a huge amount of increased risk. If your risk of developing a disease is six percent, for example, an increased risk of 32 percent would only bump you up to around eight. But it’s not nothing. There’s a reason why people in occupations where exposure to dust and air pollution is common also tend to get COPD and asthma more often. Decades of breathing in irritants is bound to have an effect. Bleach and other disinfectant fumes are harmful to your lungs, precisely because they’re good at disinfecting. Their job is to kill microbes, but the way they do so will generally also kill (or at least irritate) bits of your respiratory tract.

But breathing in bleach fumes once a week won’t kill you. It’s not good for you, but you’ll probably be okay. And there are far more significant things you can do to prevent COPD.

Even for those with occupational risks, other factors are more dangerous

If you want to avoid getting—and dying from—COPD, avoiding cleaning products shouldn’t be your chief concern. Not smoking, or quitting as soon as possible, is far more important. About 75 percent of the 16 million people with the disease were smokers at some stage (and 39 percent of sufferers keep smoking). They are 12 times more likely to die from COPD than non-smokers, and account for 80 percent of all COPD-related deaths.

That shouldn’t come as a surprise. Inhaling toxic smoke irritates the lining of your lungs, and that irritation can produce chronic obstructions. It’s also possible that smoking marijuana can increase your risk of COPD, though there hasn’t been enough research to know for certain.

This isn’t to say that bleach fumes are fine. They’re clearly not. There’s a reason our lungs burn if we inhale too much of them. But it’s important to note that disinfectants are not the main cause of COPD. The most dangerous thing about bleach fumes, really, is that if you combine them with ammonia (one of the main ingredients in Windex) they create chloramine gases, which are highly irritating. Even more dangerous: mix bleach and an acid like vinegar to create deadly chlorine gas, which has been used as a chemical weapon. It is possible to really hurt yourself with cleaning products, so none of this is to say that home users shouldn’t take care.

So try to stay away from bleach, but don’t stress too much the next time you disinfect the toilet. Ventilate your bathroom properly, and you should be fine. More importantly? Don’t smoke.