Alberta doctors issued a warning last week saying people shouldn't leave hand sanitizer in a hot car for too long because it could lead to a fire, but Toronto Fire Services is now contradicting that claim.

In a daily COVID-19 newsletter distributed to physicians, volunteers and staff, doctors at Alberta Health Services said Friday that there are several risks associated with leaving hand sanitizer in a hot car. 

"With extended exposure to high temperatures, the alcohol in the hand sanitizer will eventually evaporate, causing it to lose its efficacy," they wrote. "Additionally, there is a potential fire risk to storing hand sanitizer in your car. In extreme heat, it can ignite due to its high alcohol content."

The recommendation was widely reported on and caused many to share the safety tip across social media platforms, but Toronto Fire Services is now attempting to debunk it by tweeting that no, hand sanitizer will not actually randomly burst into flames if left in a hot car for too long.

"Hand sanitizer wont spontaneously combust or explode if left in a hot vehicle," wrote TFS on Twitter Tuesday afternoon. "Containers should be kept upright and properly sealed to avoid leakage. Containers shouldn't be left in direct sunlight as an added precaution."

1. Is it safe to leave hand sanitizer in a hot vehicle?

Hand sanitizer wont spontaneously combust or explode if left in a hot vehicle. Containers should be kept upright and properly sealed to avoid leakage. Containers shouldn't be left in direct sunlight as an added precaution pic.twitter.com/4W1uerTTzg

— Toronto Fire Service (@Toronto_Fire) May 26, 2020

The fire department did acknowledge, however, that alcohol-based hand sanitizer is flammable and may give off "flammable vapours" which could ignite if exposed to open flame or an ignition source.

"Caution should be used to keep away from open flames and avoid sources of heat," they wrote.

TFS also tweeted advice for those wondering if it's safe to smoke after using hand sanitizer, saying hands should be rubbed together until they're completely dry when using the substance and "people should be especially careful if attempting to smoke, light candles, or use a gas stove immediately after applying hand sanitizer."

In a blog post published last week, the National Fire Protection Association (NFPA) in the U.S. echoed TFS' claims. 

Can hand sanitizer spontaneously ignite in a hot car? There are currently questions circulating on social media and in the news over whether bottles of hand sanitizer can spontaneously catch fire if left in a hot vehicle. The short answer is no, it can't. https://t.co/7Fx34MxBNr pic.twitter.com/vMDcTdu3rK

— NFPA (@NFPA) May 22, 2020

"Despite some information currently being released on social media and in the news, the short answer is no. From a fire safety standpoint, it is not unsafe to leave hand sanitizer inside a hot vehicle," they wrote.

They added that hand sanitizer would actually require temperatures to reach over 700 degrees Fahrenheit (371.11 C) to spontaneously ignite. 

So while most don't seem to agree with the Alberta physicians that hand sanitizer alone in a hot vehicle is a fire hazard, experts do concur that the substance can be dangerous if not used properly and should always be kept away from flames and other ignition sources.