Some pollutants float into the sky. Others float into your nose. Guess which one you'll notice first.
"Mommy, why is the sky gray?"
Because of humanity's thirst for gas-guzzling vehicular independence and startling lack of interest in developing a more eco-friendly alternative energy source, honey.
"And why do people smoke, mommy?"
Well, honey. Some people smoke because they think it looks cool. Other people smoke because they've been smoking for a very long time and now it's really hard to stop.
"But why don't they just eat cotton candy, instead?"
Because then they'd be eating too much sugar, honey. And too much sugar isn't good for you either.
"But at least if they were eating cotton candy instead of smoking or contributing to the build-up of greenhouse gases by driving, then the rest of us who don't do those things wouldn't have to breathe in the dirty air."
Well you see, honey, a lot of people don't care about other people's feelings or health. They only care about self-gratification and therefore choose to ignore the startling truths about second-hand smoke and global warming.
"Is that why we have to buy this Blueair GO SmokeStop Unit? To remove the heavy gaseous pollutants from the air we breathe in our own home?"
That's right, honey. We depend on the progressive carbon filter with a honeycomb-type structure to improve airflow with its hundreds of odor and gas absorbing carbon pellets. But we also bought it because you insisted on a brachycephalic dog who emits plenty of her own noxious gases.