The US Coast Guard promulgated a final rule amending its regulations for fire suppression systems on several classes of commercial vessels. The amendments clarify that approved alternatives to carbon dioxide (CO2) systems may be used to protect some spaces on these vessels, and set general requirements for alternative systems. Additionally, certain new CO2 systems must be equipped with lockout valves and odorizing units to protect persons after a CO2 discharge. The amendments come into effect on July 9. 77 Fed. Reg. 33860 (June 7, 2012).