The Environmental Protection Agency 's Tier 4 diesel engine emission reduction mandate in 2012 , enacted to reduce air pollution including particulate matter and nitrogen oxides , helped drive up fairway mower prices .
Mower manufacturers had to increase digital technology to meets its standards .
The Environmental Protection Agency 's Tier 4 diesel engine emission reduction mandate in 2012 , enacted to reduce air pollution including particulate matter and nitrogen oxides , helped drive up fairway mower prices because mower manufacturers had to increase digital technology to meets its standards .