Guidelines & Tools The IMPROVE Algorithm Share SHARE Facebook share Twitter LinkedIn Copy URL Email Download Download the-improve-algorithm en Added on: 06 September, 2025 Breadcrumb Home Resource Library The IMPROVE Algorithm The IMPROVE algorithm for estimating light extinction was adopted by the U.S. Environmental Protection Agency (EPA) as the basis for the regional haze metric used to track progress in reducing haze levels for visibility protected areas under the 1999 Regional Haze Rule (RHR). The RHR uses the IMPROVE algorithm to estimate light extinction, which is then converted to the deciview haze index.