Air. Write in reasonable detail, using the macroscopic nature (our experience) and microscopic nature (molecular level) the composition of air, pollutants in air, where pollutants come from, how they impact health and environment, and what steps are being taken to keep air clean. Share your thoughts on this topic.

Or

Water. Write in reasonable detail, using macroscopic nature (our experience) and microscopic nature (molecular level) the composition of water, pollutants in water, where pollutants come from, how they impact health and environment, and what steps are being taken to keep water clean. Share your thoughts on this topic.