Simplify the following text for a Grade 9 native English-speaking person.
Original: The first commercial designs were introduced in passenger automobiles during the 1970s with limited success . Broad commercial adoption of airbags occurred in many markets during the late 1980s and early 1990s with two airbags for the front occupants , and many modern vehicles now include four or more units .
Simplified: In the 1980s , the first commercial airbags appeared in automobiles .