It cannot be denied that some sort of poisonous gas was used near Damascus with devastating effect. This is a fact. What is no fact is that it is clear who perpetrated the attack. The permanent statements of western politicians pointing at the syrian government are not evidence based and impartial but an intentional method to manipulate public opinion. There seems to be another fact to arrive at: That the rebels/“activists“ lied:

The sophisticated level of post-attack orchestrations by the opposition:
– immediate social media uploads reporting chemical attacks on 4 different suburbs/outskirts of Damascus
– spreading the apparently exaggerated claim of 1300 dead
– the lining up of heart breaking children corpses in almost total absence of rebel dead

and by contrast the relatively late first reaction of an obviously surprised government side suggest that one party in this conflict had a plan and a detailed chain of events to follow, while the other was caught in „shock an awe“ failing to publicize their version of the story through high ranking officials and at the right time (earlier than the rebels). The syrian government had no real story to tell.
By now, it seems that there were at most 350 dead, which is still a lot, especially given the high number of children deaths, but almost a 1000 casualties less than the very first horror reports. Then it seems, that only one place was really subject to a gas attack. These corrected versions that are either untold or played down by mainstream media in the days following the attack are no minor details: The claim of a four-fold almost simultaneous chemical attack and the high casualty figures were meant to assume that such a well-coordinated attack can only be carried out by an army with regular command and communication structure.

If the article below regarding the „Doctors without borders“ (Medicins sans frontieres) is true, then the statements by this organization cannot be considered 100% reliable and have to be taken with a grain of salt:
landdestroyer.blogspot.co.uk/2013/08/doctors-behind-syrian-chemical-weapons.html