Sierra lives in a southwestern town in a valley where air pollutants sometimes settle. The mountains that surround the town keep air pollution from blowing away. Sometimes Sierra can actually see the pollution in the air. Which choice is NOT a source of outdoor air pollution? A. Car emissions B. Factory emissions C. Radon gas D. Volcanic eruptions

C. would be the answer.

Explanation:

Radon gas is a major indoor pollutant, not outdoor. The rest of the choices can cause outdoor air pollution.

nope, but i have cleaned my brush in my cup of not as potentially harmful but nevertheless, very upsetting for scottish/british folks. especially if you've used the last teabag for it

explanation:

there could be something in that . . i am indeed an old scottish man!

there's a bit of bolshie-ness with it too though. i won't let go of the old ways . . tea and whisky . . whether the young whippersnappers like it or not!