More than chemicals and pollution, I think a certain type of people are toxic for us too. These people are those who would have all the pleasures in their lives but will still roam around with a droopy face. Ask these people how was their 2 week long vacation in a five star resort in Bahamas and they will answer that the baggage collection line was too long on the airport.
They act sad and depressed and love to pull everyone down with themselves. Such people should be said good bye to, from a mile away.
I am sure, you must have encountered at least one such person in your life.
Tell me how you deal with them.