The 20-county Atlanta region has finally met 1997 federal air quality standards, according to environmental regulators. The region met the standards as of 2010, but it became official with a notice in the Federal Register published last month, according to the Atlanta Regional Commission.

The region still must demonstrate a plan to continue meeting the standards over the next 20 years, regulators said. It is also preparing for tougher regulations that are on the way.

In the late 1990s, the region temporarily lost federal funding for road widening because of its noncompliance with federal air quality rules.