Test methods and procedures may be modified for determining emissions of contaminants other than particulate matter, SO2,H2S, total reduced sulfur (TRS) and NO2 from stationary sources in a manner consistent with accepted air pollution testing practices and with obtaining accurate results which are representative of the conditions evaluated. The modifications shall be subject to the approval of the Department and shall be clearly indicated in the report of test results.
25 Pa. Code § 139.15
This section cited in 25 Pa. Code § 123.45 (relating to alternative opacity limitations).