Medecins Sans Frontieres says doctors have treated about 3,600 patients with 'neurotoxic symptoms' in Syria and that 355 of them died.
Neurotoxicity hits people who are exposed to toxic substances and suffer problems to their nervous system as a result.
Britain has directly accused the Assad regime of gassing hundreds of Syrian civilians amid warnings only 48 hours remain to find proof.
New videos show the eyewitness accounts of four men who witnessed an alleged chemical attack on Zamalka, a suburb of Damascus.
These are the images of the remains of rockets which, according to the men stood by them, delivered poisonous gas to a suburb of Damascus.