我也看到过这个粉尘的理论。但当时施工开始，还没有开始用热源和焊枪，

有个从上到下的照明灯，那也是在外面的脚手架，没在屋顶里面。。。哎，不知道

所有跟帖： 

• If it's arson and surveilance cameras didn't catch it, --worldance-- ♀ (87 bytes) () 04/20/2019 postreply 13:14:49

• Also, if someone intentionally left flammable --worldance-- ♀ (164 bytes) () 04/20/2019 postreply 13:23:02

• No, i just wanted to say that such possibility can't be rule out --worldance-- ♀ (33 bytes) () 04/20/2019 postreply 18:28:28