The Portland Metro area and Clark County share the same air shed for ground level ozone and carbon monoxide. The region is currently in compliance with Federal Clean Air Act Amendments of 1990. Until 1997, the region was not in compliance and was designated a non-compliance area. Emissions in one part of the region can affect other parts of the region. Carbon monoxide levels are an especially sensitive issue near residential areas.
Air quality is monitored by a different agency in each state.
The agencies work together to coordinate implementation of the air quality standards for one bi-state region and plan additional coordination efforts for the future. The TCMs are similar for the Portland and Vancouver Metro areas but not the same. Additional TCMs will be triggered if the area reaches non-compliance. DEQ and DOE are required to coordinate their response to achieve compliance but are not required to implement the same control measures if the area were to fall into non-compliance again. Oregon and Washington coordinate clean air day declarations in response to ozone problems.