There seem to be lots of different kinds of portables. Some are basic, some are quite fancy. I am sure the district will assert that they are all "certified" or something. I believe Los Altos Elem. School District has very fancy portables.

A true story: many years ago, when I first moved to this area, my class was in a portable (which I had not experienced prior to moving to California) and it made me feel ill but this may have had more to do with the air conditioning. I actually fainted once on leaving the room and going out into high temperatures outside. I ALWAYS felt uncomfortable in that portable. Too bad I was unable to voice my discomfort. I have visited portables periodically since that time, and don't particularly care for them but haven't felt ill or anything.

Portables are pretty well regulated by the State Division of Architecture. They usually have heat pumps and a healthy amount of outside air. I suspect the early problems with outgassing of materials has pretty well been resolved.

I taught in one years ago, and other than the unsightly exterior and the proximity to my school's parking lot, I actually preferred it to the regular classrooms. It was spacious, with independent heat/AC control, and the soft wall coverings that you can easily put a pin or staple into to decorate the room. I never heard any complaints from students or parents, although I had one colleague who thought teaching in a portable was contributing to some respiratory issues.