Concentrations of sulfur dioxide in ambient air as measured by an approved method for each averaging time must not exceed the following concentrations:

1. (1) Annual average: 10 ppb as a three-year average of annual arithmetic means for any calendar year at any monitoring site as determined by appendix T of 40 C.F.R. part 50, and as measured by the reference method described in appendix A-1 of 40 C.F.R. part 50 or as measured by an equivalent method designated in accordance with 40 C.F.R. part 53.

2. (2) 1-hour average: 75 ppb as a three-year average of the annual 99th percentile of the daily maximum 1-hour average concentrations recorded at any monitoring site as determined by appendix T of 40 C.F.R. part 50, and as measured by a reference method based on appendix A-1 of 40 C.F.R. part 50, or as measured by an equivalent method designated in accordance with 40 C.F.R. part 53.

   NOTE: This rule is included in the State of Oregon Clean Air Act Implementation Plan that EQC adopted under OAR 340-200-0040. NOTE: View a PDF of referenced EPA Methods by clicking on "Tables" link below.

   [ED. NOTE: To view attachments referenced in rule text, click here for PDF copy.]

Statutory/Other Authority

ORS 468.020 & 468A

Statutes/Other Implemented

ORS 468A.025 & 468A.035

History

DEQ 27-2025, amend filed 08/18/2025, effective 08/18/2025
DEQ 13-2019, amend filed 05/16/2019, effective 05/16/2019
DEQ 7-2015, f. & cert. ef. 4-16-15
DEQ 11-2013, f. & cert. ef. 11-7-13
DEQ 6-2001, f. 6-18-01, cert. ef. 7-1-01
DEQ 14-1999, f. & cert. ef. 10-14-99, Renumbered from 340-031-0020
DEQ 4-1993, f. & cert. ef. 3-10-93
DEQ 24-1991, f. & cert. ef. 11-13-91
DEQ 8-1988, f. & cert. ef. 5-19-88 (corrected 9-30-88)
DEQ 37, f. 2-15-72, ef. 3-1-72