The world’s busiest international airport, London Heathrow, unveiled a new electronic “sniffer dog” on Monday, becoming the first in the world to trial the new screening technology.

The “Sentinel II” portal “sniffs” passengers as they pass through a detection arch, analyzing air that is blown across their bodies for particles of explosives or other banned substances, according to airport operator BAA.

Alongside the sentinel, BAA is testing a new three dimensional X-ray machine. Using special glasses, operators gain an enhanced 3-D view of objects in hand luggage.

“The new technologies add yet further deterrent to anyone approaching the airport with sinister intent,” said BAA’s Director of Security Ian Hutcheson. “I look forward to their wider introduction across our airports.”

Staff found the equipment effective and easy to use, he added. The two systems are being tested at Heathrow’s busiest terminal — Terminal One — which handles around 23 million passengers a year.