A chemical weapons expert involved in the apparent discovery of continued chemical weapons attacks in Syria told ITV News earlier this week that chlorine use is "simple to identify".
Hamish De Bretton-Gordon told Diplomatic Correspondent John Ray that Syrians should be armed with information on how to identify such attacks.
He added, however: "It's very, very non-persistent - once it's released it will remain active for, at the most, minutes.
"If there is a strong wind and if it is hot as it is in Syria it will disappear very quickly."
More top news
The final of the 'Big 6' energy firms to cut prices - EDF - has announced it is reducing gas tariffs by just 1.3%.
Memorial and Learning Centre to use digital technology to commemorate and educate about the Holocaust
ITV News returns to Bergen-Belsen with Bernard Levy, a Jewish British army officer who was only 19 years old when he liberated the camp.