Poor tenants. Upstairs flat roof unit is too hot!

[Jon L.]

We have a 15 unit, two story apartment complex that has a flat roof. All the upstairs units are extremely hot during the summer in southern California. We replaced the roof 2 years ago with a white TPO material, which promised to reduce heat(before it was gravel and tar) They installed 1 inch foam over the gravel and tar, and then installed the TPO on top. Of course, I still can't tell the difference in heat reduction even though it's a California Title 24, white roof that reflects heat. If I change a ceiling fan or a light in the ceiling, the screws and metal box are so hot I can barely touch it. 

Aside from ripping out all the ceiling and putting in insulation, is there a way to vent the hot air out?