Do You Follow the 2-Hour Rule?

a closer look at this important rule of thumb

I posted the above video on social media last summer to remind folks about the 2-hour rule-- that perishable food should not be left at room temperature for more than two hours.  To my surprise, it blew up with millions of views and thousands of comments. While the post got thousands of “likes,” I was startled by the push back arguing against this simple rule of thumb. Many who commented seemed offended I would even bring it up.  I had no idea there was so much confusion and passion around food safety!

Most of the comments arguing against the 2-hour rule revolved around four main misconceptions. Since we are once again in peak picnic and cookout season I thought it would be a good idea to address each one of them here, and offer practical tips for keeping your food safe to eat.

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Misconception #1: It’s not a 2 hour rule, it’s a 4-hour rule.  

First, let’s dig into the reasoning behind the 2-hour rule, a long-standing food safety guideline put forth by the USDA, FDA and CDC to help prevent foodborne illness. Bacteria thrives in temperatures between 40 and 140 degrees Fahrenheit and can double every 20 minutes in that “danger zone.” Based on that exponential growth, scientists pinpointed two hours to be the maximum amount of time consumers should leave perishable food at room temperature to keep it is safe to eat. Complicating things somewhat, since bacteria grows faster on the warmer end of that range, if food is outside in temperatures 90 degrees or higher, it becomes a 1-hour rule.

Many folks argued in the comments on my post that it is not a 2-hour rule, it’s a 4-hour rule. They aren’t entirely wrong. There is a 4-hour rule too, but that pertains specifically to retail establishments, such as restaurants and grocery stores. The time window is wider for professional kitchens because they are more controlled environments, with multiple layers of strict food safety practices in place to minimize bacterial contamination and growth.

There isn’t just one moment where a timer goes off and food suddenly goes from safe to unsafe. There are many variables, but if a food contains a pathogen, the more time it sits out and the warmer the temperatures, the more likely it is to make people sick. It is a matter of risk. 

For the record, perishable food is anything you would ordinarily keep in the refrigerator, including meat, poultry, fish, eggs, dairy products, cut vegetables and fruit, and cooked dishes. And the 2-hour rule pertains to the entire life of the food. So if a guest brings a dip to your potluck without putting it in a cooler, and their drive to your home is 30 minutes, you have 90 minutes remaining to leave that food on the out un-chilled, or 30 minutes if it’s more than 90 degrees outside, which it seems to be nearly every day this summer.

Misconception #2: That rule can’t be valid, I always leave food out for much longer and have never got sick from it.