Yesterday’s post regarding the TSA’s possible introduction of a 3.5 fluid ounce standard for carry-on liquids yielded a small storm in my e-mail inbox, including a thoroughly disposable form letter response from the TSA itself, encouraging me to check the website. Gee, great. Thanks for that.

But thanks to Benet Wilson, it also yielded this far more helpful response from Amy Kudwa in the TSA’s Office of Public Affairs:

Since the liquid threat was discovered as part of the foiled terror plot in August, TSA has worked very closely with our European partners to harmonize our overall security efforts. As a result, the EU, Canada and several other countries adopted in November a 100 ml standard for liquids. This standard most easily converts to our 3 ounce limit and is readily understood by passengers both in the US and abroad. Our 43,000 TSOs have been trained on this negligible difference and we have not seen any issues with European visitors meeting either standard. (emphasis added)

So the TSA defies the metric system and equates 100 ml with 3 ounces. Close enough for them, good enough for me.

By the way, I was wrong about a minor detail in yesterday’s post: the conversion of 100ml. I had foolishly looked at the label of a European 100ml bottle of shampoo in my bathroom, which incorrectly translated 100ml to 3.2 oz. In fact, 100 ml = 3.38140226 US fluid ounces. Effectively 3.4 ounces.

Carry on!