Enviromental Air Cielings a Bad ideal which is a Health and Life safety Issue

About 40 years ago an Architect got the bright idea what if we use the entire ceiling above a suspended ceiling as a return air duct instead of having to install all that metal return air duct.
While it might have saved money initially in the long run it has turned into a public health and life safety disaster .
You can tell these type of ceilings by use of white and silver plastic open egg crate as its known ceiling tiles which allows the return air into the ceiling which is then drawn to a large duct in roof heating cooling unit.
While you save money on the duct metal it also completely changes the codes by which all other piping and electrical work must now be done.

Because of potential acrid smoke that can kill that can be caused by wiring and plastic plumbing pipes in an environmental air ceiling these items can not be used all wiring and pipe must be metal encased or other wise encased with in drywall or the use of very expensive plenum wire must be used and you guessed it after the inspector leaves any thing goes and cileings get filled with all types of wire which are not permitted creating a very dangerous life safety issue of deadly acrid smoke,should a fire break out.
When they built Pittsburgh Mills Mall in Fraser twp Pa. a few years back they used the wrong piping in the ceilings and as a result all the stores in one area just had ceiling grid up till all the correct metal piping was installed. What a night mare for the contractor who misread the plans

Then you have the health issues the ceiling tiles end up with a thick coating of dust on them and when you go to lift them out after a few years its dust everywhere and people end up getting sick from all the dust. What a health mess for any one with asthma.
In short the initial cost savings end up costing way more than any initial savings. especially when you figure in all the increased costs of plenum wire and pipe. actually there is no savings yet they keep insisting on putting in these ceilings knowing all along codes will not be followed and lives will be put at risk but the code making bodies can care less. Which is owful nice of them.