A healthy lawn is dependent in proper nutrition and personalized attention.  Studies by the University of Minnesota and Iowa provide information that a healthy, vigorous lawn is a positive contribution to a cleaner environment.  A study done by UC-Irvine in 2010 concluded that maintaining a healthy lawn is a positive sequester of carbon.  A healthy lawn with good plant density provide many benefits:

Traps large amounts of atmospheric dust

absorbs gasous pollutants like Co2

reduces noise by absorbing, deflecting, reflecting, and refracting sounds

reduces discomforting glare and light reflection

every 25 sq. ft. of lawn provides enough oxygen for one person for one day

Up to a 15% increase in home value