A boiler breakdown at Suncor Energy’s oil refinery north of Denver on Thursday led to elevated emissions of hydrogen sulfide, a potentially deadly gas, and other pollutants, and an Adams County commissioner is asking Suncor to install a full-time air monitoring system to protect people in surrounding areas. Colorado Department of Public Health and Environment officials who issue Suncor’s operating permits also expressed concern following the latest equipment failures at the refinery, located along Sand Creek just north of Denver in Commerce City. Suncor officials said the concentrations of hydrogen sulfide emitted Thursday were “acceptable” and that company crews used portable gas-monitoring devices as part of their emergency response. Suncor operators of the refinery repeatedly have had problems leading to elevated air and groundwater pollution in north Denver and Commerce City.