Via al Jazeera: http://www.aljazeera.com/indepth/features/2013/05/2013523155639566436.html
A former scientist for the Syrian chemical weapons programme said the regime of President Bashar al-Assad has enough of the nerve agent sarin to "eradicate the whole of Damascus, Homs, Hama, and Aleppo".
Speaking to Al Jazeera on condition of anonymity after he fled from Syria, the chemist added that the regime is not likely to unleash its chemical stockpiles unless it “no longer cares about the world knowing".
"If the regime is to fire a Scud-B with a chemical warhead filled with sarin, the missile would create a chemical cloud in the atmosphere that is 3km long and 500m wide, which could be fatal to all people under it," the chemist said.
He claims that the regime has only used sarin nerve gas in small quantities to halt rebel advances in four towns in the suburbs of Damascus, in Aleppo’s Sheikh Maksoud district, in Idlib's Saraqeb town and in Homs' al-Khalidiyeh district.
"The intention was to incapacitate rebels and force them out of strategic areas, while keeping the deaths among their ranks limited," the chemist said, who added that he was speaking out "to dispel the myths on chemical weapons in Syria".
Al Jazeera was able to verify his former position at the chemistry institute of the Centre for Scientific Studies and Research (CSSR), Syria’s main agency for the development and enhancement of weaponry. It has been reported that a CSSR site in the Damascus suburb of Jamraya was targeted twice earlier this year by Israeli airstrikes.
More at link. Warning, some of the comments on it will make you cringe.
Edited because I forgot to put in the link.