On January 10th, 2017 Russian Sappers clearing mines in East Aleppo found a huge stockpile of Chlorinates manufactured in Saudi Arabia by Sachlo which Rebels had been using to manufacture Chlorine filled Mortar shells. 

Meanwhile Human Rights Watch Incorporated which was largely responsible for propaganda claims of gas attacks in FY2015 held funds of $240m including a $100m contribution by George Sorous and several significant contributions from NATO governments who are determined to force regime change in Syria.

In other words let us not beat around the bush. Western Nations funded a propaganda campaign to falsely accuse Assad of gassing civilians inside Aleppo. Among their many fake claims was that 12,958 barrel bombs each caused a 7.6 Richter scale tremor. 

There were no such earthquakes in Aleppo and alleged gas attacks are equally fake claims.