Nightly News | September 04, 2012
>>> again tonight. and some travelers may decide they have reached their limits when they hear about this one. for all we've gotten used to over the years, shoes off, belts off, laptops out, no liquids allowed, there's something new. would you believe testing the liquids you yourself buy inside the terminal where we're allowed to have liquids? our report tonight from nbc's tom costello.
>> reporter: an unexpected sight at the columbus airport, two tsa officers holding a test strip over passenger's drinks to check for explosive vapors after the passengers had already cleared security and bought the beverage in the concourse. dan holland was there with his wife and son.
>> having someone come up to me and demand i submit to another search without really any probable cause seems a bit much.
>> reporter: the tsa says the drink screening has been going on for years as it employs multiple layers of security throughout the airport. it limited passenger's carry on liquids and gels in 2006 . after terrorists plotted to blow up u.s. bound passenger planes with u.s. explosives over the atlantic. screening drinks bought in the gate area is meant to guard against potential threats from inside the concourse, perhaps an employee who could smuggle in an explosive and hand it off to a passenger. but while airline passengers face the prospects of additional screenings every day, neither the trusted vendors nor the airport employees are screened every day. and the tsa won't say how often they are screened. screening drinks bought in a supposedly secure environment garnered mixed emotion today.
>> kind of ridiculous, excessive maybe.
>> i would rather get on a plane knowing i'm safe.
>> it's a worthwhile thing for them to do. you can't be too safe.
>> i am a little concerned about how invasive its getting.
>> passengers who decline the beverage check may be denied boarding. two years ago the tsa invited us into its laboratories as it tested equipment it hoped could sniff out explosives inside plastic bottles .
>> we're trying to measure and quantity how much of a gas is leaking out from a liquid via the plastic seals and bottles.
>> reporter: foolproof technology has proven elusive. an unpredictable offense at airports remains the best defense . tom costello, nbc news, washington.