The Michigan-based company, which reported $5.6 billion in 2014 revenue, also agreed to a $312,000 civil penalty and to fund a $150,000 mitigation project in California’s San Joaquin Valley to replace or retrofit higher-polluting wood-burning appliances with cleaner ones.

Guardian's modifications will control emissions of nitogen oxide. The company, which has 17,000 employees in 25 countries, said it was the first maker of flat glass, also known as float glass, to sign what it called a “mutually beneficial agreement” with the governnment under its national enforcement initiative of clean air rules.