Explain Pollution to a Person from another Planet

This slender, green-spotted alien approached me and said, "Excuse me, but why is your world so fucked up?"
I looked at the alien in disbelief! He was serious about his question too.
"Uh...What? What do you mean by, "I held my tongue. " ...messed up?"
"I'm talking about your planet you fool. Why is it in such bad conditions."
I looked at the alien once more.
"I'm talking about greenhouse gases!
"Oh, well. Its because we use fossil fuel," I replied. Trying to answer its question to my fullest.
"Then, would you care to explain air pollution? I'm doing a project on other planets--"
"Where are you from, " I interrupted.
"I'm from Reqwrt," the alien answered.
"Okay, fair enough. Lets begin. Air pollution are toxic gases from cars, trucks, agriculture, cigarettes, and energy generation that rises to the air and causes respiratory problems, as well as effect ecosystems in a negative way."
"That's interesting, but what is it?" The alien seemed confused.
"I just explained it to you."
"....Oh."
"Well, I didn't understand a word you just said," the Alien exclaimed.
"How about this. DioujfksjfaKLFL;SIFYERUIGDADFHLFASJKGLGH"
"Now that's just mean. I didn't speak retard with you, so don't speak gibberish with me."