ELI5: Explain Like I'm 5

Portable emissions measurement system

Do you know that our cars and trucks can make dirty air? That's what we call emissions. They can come out from the tailpipe of a car or truck and pollute the air outside. It's not good for our health and for our environment.

To make sure that cars and trucks are not making too much dirty air, there are machines called Portable Emissions Measurement Systems or PEMS. They look like big boxes that can sit at the back of a car or truck while it's driving.

PEMS can measure the amount of dirty air that the vehicle makes while driving. It can also measure how much fuel the car is using, how fast it's going, and many other things. There are tiny sensors inside PEMS that can check the air quality in real-time.

By using PEMS, experts can tell if a car or a truck is following the rules on emissions. They can also see which ones are not following the rules and need to be fixed. PEMS make it easier for governments to protect people's health by making sure the air we breathe is clean.
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