Passage: On 21 August, an alleged chemical attack on the Ghouta region claimed lives of hundreds of people, both civilians and rebels. Estimates of dead varied from 355 up to 1,429.On 22 August, according to the Syrian opposition, the Syrian Army launched a new offensive against rebel positions in Rif Dimashq. The Army entered Erbine, Harasta, Jobar, Zamalka and Ain Tarma, but without taking full control. They did however capture strategic points.

Question: When did the chemical attack occur?
21 August