Airboxes were first "banned" after the 1976 spanish GP, safety being the main reason behind it. These airboxes were responsible for the ram-air effect (annex 1), which acted as a forceful feeding of air caught in the airbox intake into the carburettors, similar to a forced induction system, but passive instead of active (like turbos and superchargers). Furthermore, it was not uncommon for ariboxes (specially in back of the grid teams) to fall off after a small shun or if the mechanics didn't screw the bolts that held the airbox tight enough. They'd be first limited in height and intake area, later being discontinued due to low benefits in speed and adding drag to the cars (annex 2).
The airbox would make a return to F1 in back of the grid cars in the mid 80s though, as leyton house march showed up in 1987 with the march 871 chassis running a Ford DFZ 3,5L engine, which appeared more often than not with a big airbox that'd bifurcate and present an intake either side of the driver (annex 3). Later, in 1989, the FISA (FIA) would "unban" the airboxes, with not so many teams presenting them later in the season, but making an appearance in pretty much every car of the 1990 season (annex 4 & 5)
