Before catalytic converters, starting a gas-powered vehicle could choke the surrounding area with smog.

(LOS ANGELES) Cars on the road today are 99% cleaner than they were in 1970. Air quality in the United States is much, much better as a result. In Los Angeles, where I live, lead levels in the air were 50 times higher in the 1970s than today, and the amount of lead in kids’ blood has plummeted.

What made that drop possible is arguably the most important environmental technology ever invented: the catalytic converter.

Originally published on theconversation.com, part of the BLOX Digital Content Exchange.