The United States and Canada have jointly applied and been approved by the IMO for an emissions control area up to 200 miles off their casts, excluding Alaska and the Arctic. This requires ships passing through these waters to comply with Tier III emissions limits for NOx, which reduce NOx emissions approximately 80%. Subsequent IMO resolutions delayed compliance with these requirements for other ECAs, but the North American ECA was grandfathered so that emissions controls apply to ships constructed in 2016 onwards.