I had to leave simmering pot of pork stew after an hour. I turned it off and came back 3 hours later. Do I have to throw it away? It is luke

You say it was simmering, which means it was well above 135 degrees, the upper end of the temperature danger zone (41-135 degrees). However, the health code states that it must be cooled to 70 degrees or below within 2 hours, as 70 to 135 degrees represent the range of the greatest risk of bacterial growth. You then have another 4 hours (usually under refrigeration) to loser the temperature to 40 degrees or below. Inasmuch as the pot had been simmering, and no cooling measures were taken (setting it in a sink of icy water, or immersing plastic bottles filled with frozen water in it), it is quite doubtful that it fell below 70 degrees with the requisite two hours. To be safe, throw it out, and consider it a lesson learned. You have abundant company, as many of us have likely been in this position.

I would eat it. It didn't drop below 140 in 5 minutes or probably in 60 minutes. Chef Ono is the food safety expert!

Despite food hygiene guidelines, I, personally wouldn't throw away a dish that had sat for 2 hours at room temp - I would definitely make sure I reheat it to above 72 degrees C for a good length of time, but there is no way I would bin it unless it smelled off, or had sat there for a far longer period than this. I know food regs are there to protect us, but common sense should prevail in more cases than it does - if you are happy with the way it looks, smells etc and you aren't feeding 'vulnerable' people I would carry on and eat it!

Thank you.

Unfortunately, probably. I hate to see your hard work wasted, but especially this time of year, it's probably been in the danger zone too long. There are a lot of variables, but according to this, the maximum time foods should generally be held safely at room temp is two hours, in some circumstances no more than one. http://www.four-h.purdue.edu/foods/Time%20temparture%20danger%20zone.htm

USDA consumer guidelines state food should not remain in the Danger Zone (40-140F) for longer than 2 hours. Considering the time it would take for the pot to cool from boiling and the time you were away, you should be safe assuming the dish was cooled promptly upon your return. As an added measure of safety, bring the stew back to a boil before consuming.

Read more here:
http://www.fsis.usda.gov/wps/wcm/connect/8b705ede-f4dc-4b31-a745-836e66eeb0f4/Danger_Zone.pdf?MOD=AJPERES