The Suncor oil refinery upwind of Denver that recently belched pumpkin-colored gas and dust into the sky, worrying residents and prompting highway closures, released far more sulfur dioxide than previously known — 75,600 pounds, 150 times beyond a 24-hour limit that triggers an investigation, according to a company letter obtained Friday.

Suncor spokeswoman Lisha Burnett told reporters shortly after the Oct. 14 event that no sulfur dioxide had been detected near the refinery, but company officials later acknowledged the sulfur dioxide release had exceeded the daily limit of 500 pounds. The company and state officials say the release did not pose any health risks...

The refinery has been under scrutiny by state regulators for years over air pollution problems and remains under investigation...

*Sourced by RepRisk due diligence on ESG and business conduct risks, www.reprisk.com.