Construction sites in Cook County are about to get greener.
County Board President Todd Stroger signed an ordinance Thursday that will cut diesel pollution from construction equipment.
Contractors must immediately begin using ultra low-sulphur fuel. Then they must install filters to cut emissions 50 percent by 2011 and 90 percent by 2014.
Diesel emissions include tiny particles that can lodge deep in the lungs and cause respiratory and heart problems. It's also suspected of causing cancer.
The Respiratory Health Association of Metropolitan Chicago says diesel soot causes about 755 deaths, 1,000 heart attacks 17,000 asthma attacks in the area annually. State data show construction equipment is one of the biggest sources of diesel soot.