Reports are that victims had pinpoint pupils and suffered convulsions, which doesn’t fit the profile for phosgene.
https://emergency.cdc.gov/agent/phosgene/basics/facts.asp
https://emergency.cdc.gov/agent/phosgene-oxime/basics/facts.asp
There is no definitive proof either way. Assad may have done it, but it is possible that a conventional bomb struck a terrorist facility. See posts 24 through 29
http://www.freerepublic.com/focus/news/3543150/posts?page=24#24 Also 16 and 12 in the same thread for background.
Good stuff, thanks Ray!