Attribution of Haze (AoH)

Attribution of Haze (AoH) refers to the evaluation of emissions from human and natural sources that contribute to poor visibility conditions within class one areas.

The WRAP has established an Attribution of Haze program for the purpose of preparing a report describing the sources and locations of emissions that are attributing to haze in Class one areas.

For additional information and links about the WRAP Attribution of Haze workgroup, or to view the Final Phase 1 Report, click the following link:

Source: Air Resource Specialists Inc. 2005. Attribution of Haze Report (Phase 1) Geographic Attribution for the Implementation of the Regional Haze. Available at

Western Regional Air Partnership. 2004. Attribution of Haze Project Plan. Available online at