From the brains behind brains on, this is the Moment of Um.

Moment of Um comes to you from APM Studios. I'm Doug the school bus driver.

Um. APM Studios. I'm Doug the school bus driver. I've been driving this school bus for the past 30 years,

and I know for a fact I have the best job in the world. I loved school when I was a kid, my teachers,

the fresh new pencil smell at the beginning of the school year, but especially the school bus.

Riding back and forth to school was my favorite.

It's when I got to hang out with my friends, trade snacks from our lunches, and sit on those brown vinyl seats that stick to the back of your legs.

There's nothing like it.

So when I grew up, I decided to become a school bus driver. The only

thing I don't love about my school bus is the smelly exhaustumes that come out of the back.

The exhaust makes my nose itch and sometimes...

It makes me sneeze. Say, where do exhaust fumes come from anyway?

I know it has something to do with burning gasoline, but I'm not sure what.

Oliver was wondering about this, too.

So I found an expert who knows a lot about this.

So it's just vented byproducts of the combustion reaction that makes your car work.

I'm Josie Anardo at the Ohio State University.

I'm a new assistant professor.

Chemistry is a lot of things from our perspective as people who do research is that it's the science that kind of looks at how energy changes in our everyday lives. Generally speaking,

like you have gasoline, right? And gasoline is consisting of hydrocarbon, so it's carbon and hydrogen

bonds together. Essentially, it reacts

with, like, oxygen in the air, and it combusts. So combustion reactions are a specific type

...