Does Your Mask Pass The Candle Test?

While the idea of wearing a mask has its own controversy, the fact that many local and state mandates require a mask is no longer up for debate. That moves us forward to the next question which is: Which kind works best? Fortunately, everyone's favorite science guy, Bill Nye, took to TikTok to help us understand the efficacy of masks, by putting them through the candle test (via Time). Nye shows us what happens when a person wearing a certified N-95 mask properly goes to blow out a candle. Spoiler alert: The candle stays lit. This helps show viewers how little air and respiratory secretions can be transferred by hospital-grade personal protective equipment (PPE).

As Nye describes it, a good mask blocks "particles from your respiratory system from getting into my respiratory system." But what about non-N-95 masks? How effective are regular cloth masks, disposable masks, and bandanas? Nye added a second TikTok video that tests out common mask options like a scarf and a homemade cloth mask. Almost all the masks he tested passed the candle test, except the loose scarf. Of course, there are a number of factors that contribute to mask efficacy, but the candle test is a good way to start.

Harvard Medical School physician Dr. Abraar Karan casts doubt on this method. "Being able to blow a candle out may be some measure of how well particles can exit your mask, [but it's] unclear to me how reliable that is as a proxy for small aerosols exiting with normal speaking or coughing," he says (via KUOW). Amy Price, senior research scientist at Stanford's Anesthesia Informatics and Media Laboratory notes that the candle test provides a good rule of thumb — while the candle test won't tell you exactly how effective your mask is, it will tell you if your mask is a definite fail.

To further understand if your mask is working, examine the material and thread count of your mask. Price recommends stretching your mask, and holding it up to a light source, like your phone's flashlight. If you can see through the mask, that's a bad sign. Karan also elaborates on what makes a good mask, saying, "In short, you want a mask that fits you well, and that has cotton with high yarn counts and possibly with multiple layers which many masks today do offer."