As an environmental science teacher, how would you respond to someone who tells you (a) that he or she does not believe in biological evolution because it is “just a theory, “ and (b) we should not worry about air pollution because through natural selection, the human species will develop lungs that can detoxify pollutants?
The science of evolution is based on proven scientific facts. Exactly how evolution works is is answered by theories. This site has a great explanation.
It certainly is not a fact that people will develop lungs that can detoxify pollutants. Even if they could, it takes thousands of years for anatomical changes to evolve. I can't wait that long.
It is also important to try to find out if the person would accept anything you would explain about evolution at all. Often their point of view is motivated by religion and they won't accept anything that contradicts their belief.