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Why 70 Percent Alcohol Disinfects Better than 91 Percent, According to a Microbiologist - Apartment Therapy
When you’re worried about getting sick, it’s natural to bring out the big guns, like bleach or rubbing alcohol. Both of these products are effective at disinfecting your surfaces, but did you know there’s a counter-intuitive rule of thumb to follow when you clean with alcohol? It has to do with the percentage of alcohol by volume.
You would think alcohol solutions with a higher percentage would be more powerful at killing germs on your high-touch items like phones and doorknobs, right? A lower percent-alcohol means there’s more water diluting the mix in the bottle. But according to microbiology, 70 percent alcohol is probably more effective than 91 percent for disinfecting—depending on what kind of germs you’re trying to kill.
Here’s why a lower-percentage alcohol might be a better weapon against germs:
According to Dr. Elizabeth Scott, professor of microbiology at Simmons Center for Hygiene and Health in Home and Community at Simmons University in Boston, higher-percentage alcohols are more concentrated. That means lower percentages, like 70 percent, have more water in them. Turns out, the water is actually an important ingredient here.
When you’re worried about getting sick, it’s natural to bring out the big guns, like bleach or rubbing alcohol. Both of these products are effective at disinfecting your surfaces, but did you know there’s a counter-intuitive rule of thumb to follow when you clean with alcohol? It has to do with the percentage of alcohol by volume.
You would think alcohol solutions with a higher percentage would be more powerful at killing germs on your high-touch items like phones and doorknobs, right? A lower percent-alcohol means there’s more water diluting the mix in the bottle. But according to microbiology, 70 percent alcohol is probably more effective than 91 percent for disinfecting—depending on what kind of germs you’re trying to kill.
Here’s why a lower-percentage alcohol might be a better weapon against germs:
According to Dr. Elizabeth Scott, professor of microbiology at Simmons Center for Hygiene and Health in Home and Community at Simmons University in Boston, higher-percentage alcohols are more concentrated. That means lower percentages, like 70 percent, have more water in them. Turns out, the water is actually an important ingredient here.