Colorado air regulators are unsatisfied with a Suncor Energy plan to monitor pollution around its Commerce City refinery. On Thursday, the Colorado Air Pollution Control Division announced it had demanded the Canadian oil and gas company revamp its plans for a legally required fenceline monitoring network. The agency will require the company to install additional 24-hour air sensors, lower the levels of pollution necessary to trigger emergency notifications and more frequently update a public website showing air monitoring results. Division director Michael Ogletree said the changes would more than double the cost of the system to $25 million from about $10 million. Suncor Energy, which earned $3.1 billion in profit last quarter, will cover the cost. A 2021 state law requires Suncor to install air sensors on a 3.4-mile perimeter around the facility. The system must watch for benzene, hydrogen sulfide and hydrogen cyanide.