An indirect source of air pollution is a land-use activity or development that concentrates emissions from mobile sources such as cars, trucks, construction equipment or locomotives. A common example of an indirect source is a large parking lot.
On Dec. 20, 2019, several parties petitioned the Environmental Quality Commission to adopt regulations that would reduce emissions associated with indirect sources.
According to statute, EQC has up to 90 days to consider the petition before acting. DEQ will ask the EQC to take action on the petition at the EQC regular meeting, March 18 and 19, 2020.

Public comment opportunities

The public comment period for the Indirect Source Rules Petition closed at 4 p.m. Friday, Feb. 14, 2020. DEQ will consider all comments received by the deadline when preparing a recommendation for EQC.


EQC meeting presentation and comments

DEQ staff presented information about the Indirect Source Rules Petition to the EQC at their regular meeting Jan. 24, 2020. Members of the public were able to submit verbal or written comments during the public comment period at the January EQC meeting.
DEQ is particularly interested in the public’s comments pertaining to these aspects of the petition’s proposed regulations:
  • Where indirect source regulations should apply
  • Under what conditions indirect source regulations should apply
  • Emission reductions required of indirect sources.

​DEQ currently requires indirect source construction permits only in certain areas of the state where air quality has not met the carbon monoxide standard. Within those areas, DEQ only requires permits for parking lot developments or expansions exceeding 1,000 spaces (or 800 in downtown Portland).

Oregon’s indirect source regulation dates back to the 1970s when carbon monoxide from mobile sources caused Oregon’s air quality in urban areas to violate the national standard. DEQ incorporated multiple federal, state and local emission and transportation control measures in Oregon’s State Implementation Plan, including rules to regulate indirect sources. In 1984, DEQ expanded application of the Indirect Source Rules to Medford as a requirement of the Medford CO Attainment Plan. In 1986, DEQ removed Indirect Source Rules from Oregon’s State Implementation Plan because EPA no longer required them in SIPs. But, DEQ continued to implement Indirect Source Rules at the state level. In 1998, DEQ substantially revised the Indirect Source Rules to reduce permitting requirements for construction of new parking facilities, eliminate regulations for highway projects and airports, and explicitly limit applicability to CO nonattainment and maintenance areas.

Between the mid-1970s and early 1990s, DEQ reviewed the air quality impacts of more than 400 indirect sources statewide and issued Indirect Source Construction Permits for malls, multi-family residential developments, commercial developments and road projects. By the mid-1980s, DEQ’s monitoring data showed substantial reductions in carbon monoxide emissions and fewer standard violations. While the requirements of Indirect Source Construction Permits contributed to those reductions, CO attainment is commonly attributed to increasingly protective federal vehicle emission standards. DEQ has issued fewer than 10 Indirect Source Construction Permits since 2000.

​The petition asks the EQC to adopt rules that regulate emissions from the construction and operation of Indirect Sources in cities and metropolitan service districts with a population of 50,000 or more. Petitioners propose that a variety of facilities be considered Indirect Sources, including but not limited to:

  • Parking facilities
  • Retail, commercial, and industrial facilities
  • Recreation, amusement, sports, and entertainment facilities
  • Office and government buildings
  • Educational facilities
  • Hospital facilities
  • Warehouses and freight distribution facilities
  • Rail terminals
  • Ports and marine terminals
  • Development projects

Petitioners propose that Indirect Source Construction or Operating Permit requirements would be triggered by a variety of operational and emissions thresholds, such as:

  • Construction or demolition of permanent residential, commercial, or industrial structures with area exceeding 10,000 square feet
  • Construction of parking facilities with capacity of 500 or more parking spaces
  • Excavations exceeding 8,000 square feet of disturbed area
  • Development projects exceeding $1 million total contract value where estimated construction emissions may exceed certain annual thresholds for particulate matter, nitrogen oxides, criteria pollutants or carbon dioxide equivalents or certain hourly ambient concentrations of PM2.5
  • Operating Indirect Sources where:
    • Mobile source emissions exceed certain annual thresholds of PM2.5, NOx, other criteria pollutants or CO2e
    • On-site emissions exceed certain hourly ambient PM2.5 concentrations
    • Asociated heavy duty diesel motor vehicle trips exceed 50 in a 24-hour period
    • Asociated heavy duty diesel motor vehicle trips exceed 50 in a 24-ssociated heavy duty diesel motor vehicle trips exceed 50 in a 24-hour period
    • Associated aggregate mobile source activity exceeds 750 gallons diesel fuel or gasoline in any 24-hour period.

Petitioners propose that when a source applies for either an Indirect Source Construction or Operating Permit, the application must include an Air Impact Assessment completed according to a DEQ-approved protocol and approved by an independent third-party. If an Air Impact Assessment shows that average emissions from either construction equipment or mobile source activity is likely to exceed certain thresholds, then the source must develop, implement, monitor and report on emission reduction measures. Emission reduction measures would have to be permanent, enforceable, quantifiable, and verifiable.

Petitioners propose that Construction and Operating Indirect Source Permits include, among other requirements, conditions that limit emissions from mobile source activity and operations. Average PM2.5, NOx and greenhouse gas exhaust emissions from certain vehicles, engines and equipment could not exceed certain hourly or daily thresholds.  If emissions exceeded thresholds, permittees would be required to reduce emissions. Emission mitigation could include measures and practices such as:
  • Using lower-emitting construction vehicles, equipment or engines
  • Using electric or zero-emission vehicles, equipment or engines
  • Using alternative fuels
  • Installing pollution control devices
  • Reducing vehicle trips to or from the source


Karen Font Williams