Ventura County APCD

The Ventura County Air Pollution Control District covers Ventura County, part of the South Central Coast Air Basin with Santa Barbara and San Luis Obispo counties. Its CEQA thresholds are in the Ventura County Air Quality Assessment Guidelines, adopted by the Air Pollution Control Board, first published in April 1980 and last revised in a technical revision of October 2003. Every number below is from 2003 or earlier. The guidelines are advisory: they call themselves "guidelines only," say the district does not require their use, and leave that choice to the lead agency. The district's CEQA page, last modified June 10, 2025, still describes them as advisory, says parts of them are outdated, and asks preparers to consult district staff on current projects.

Ozone precursor thresholds

Section 3.3.1 gives pounds per day thresholds for reactive organic compounds (ROC) and nitrogen oxides (NOx), set at the levels the Board found would put attainment of the federal one-hour ozone standard at risk:

The Ojai Planning Area is the Ojai Valley as defined in Article 12, Section 8112-2 of the Ventura County Non-Coastal Zoning Ordinance, plus the Ventura (Ojai) Non-growth Area, mapped in Figure 3-1. A footnote adds that the City of Simi Valley uses 13.7 tons per year of ROC or NOx, as directed by its City Council. Under a Board policy, a general development project expected to meet or exceed the criteria has a potentially significant impact, and the district recommends a Mitigated Negative Declaration or an EIR for it.

Area source and motor vehicle emissions count, as do any emissions that result from the discretionary approval. Emissions from equipment that needs a district Authority to Construct or Permit to Operate are subtracted, because New Source Review, offsets and BACT already handle them.

Construction ROC and NOx, including portable engines in the state's portable equipment program, are not counted against the thresholds, because they are temporary. They should still be mitigated when heavy-duty construction equipment would exceed 5 lb/day in the Ojai Planning Area or 25 lb/day elsewhere, and construction results are not combined with operational ones for comparison (Section 5.2). Section 7.4.3 lists four measures: limit idling, keep engines tuned, stretch the schedule during the May through October smog season so less equipment runs at once, and use alternatively fueled equipment where feasible.

Screening

Appendix F lists, by land use and year of completion, the project sizes that exceed the ROC or NOx thresholds. Section 5.3.1 calls for a model run when a single land use project is near the listed size, and a detailed run when project conditions differ from the county defaults. The tables were built with URBEMIS2002 and EMFAC2002 on the default fleet, so they do not suit truck-heavy projects such as a warehouse. The district's CEQA page now recommends CalEEMod over URBEMIS.

Other criteria pollutants and CO

For the other criteria pollutants the test is the ambient standard: a project is significant if it may cause an exceedance of any state or federal standard, or make an existing exceedance measurably worse, which may take modeling to show. Section 6.4.1 calls for a Caltrans CO Protocol hotspot screen when indirect emissions exceed the ozone thresholds and the project may significantly affect intersections operating or expected to operate at level of service E or F, and at any project-affected intersection where a hotspot might occur. The guidelines call for CALINE4 if screening indicates a possible hotspot or the screening assumptions do not fit the project. Section 6.4.2 uses the highest 1-hour and 8-hour background CO concentrations from the previous three years at the nearer monitoring station listed in Table 6-2. A modeled hotspot is significant unless mitigation brings it under the standard.

AQMP consistency

A project emitting 2 lb/day or more of ROC or of NOx that is inconsistent with the Ventura County Air Quality Management Plan has a significant cumulative impact; below 2 lb/day of both, a project that conforms to its General Plan designation need not assess consistency. For a project conforming to its General Plan designation, the test compares current population with the next year's forecast for its growth area, or for the aggregated non-growth areas excluding Ojai. Ojai has a separate procedure. The guidelines use forecasts from the most recently adopted AQMP, but Table 4-1's footnote also permits newer VCOG-adopted forecasts if their countywide population total is lower. Table 4-1 itself carries the 1995 AQMP Revision forecasts, which end in 2005. A General Plan Amendment that adds population beyond the forecast is a significant cumulative impact. In the Ojai Growth and Non-growth Areas, the residential building permit allocation in Article 12, adopted July 1982, assures consistency.

Dust, toxics and odor

• Fugitive dust. Significant when dust may cause a nuisance under Health and Safety Code section 41700, or when dispersion modeling indicates an ambient particulate standard could be violated. The district prefers controlling dust to quantifying it, and applies the Model Fugitive Dust Mitigation Plan in Section 7.4.1 to all dust-generating work: limit the disturbed area, water before grading, cover haul loads, stabilize areas idle more than four days, post a 15 mph limit, curtail work in high winds, and sweep adjacent streets daily when soil is carried onto them.
• Toxic air contaminants. A health risk assessment showing a lifetime cancer probability greater than 10 in one million, or a Hazard Index greater than 1, is significant. A screening assessment showing risk to the maximum exposed individual under one in one million and acute and chronic hazard indices under 0.1 ends the analysis; otherwise a formal assessment follows the CAPCOA guidelines (October 1993 version) and the district's supplement dated March 23, 1995. New land uses within one-quarter mile of an existing toxics source are also evaluated.
• Odor. Qualitative: a project that could create a public nuisance under Rule 51 has a significant odor impact. Table 6-3 gives screening distances of 2 miles for wastewater treatment facilities, petroleum refineries, green waste and recycling operations and mushroom farms, and 1 mile for the other listed uses, such as landfills, composting and asphalt batch plants. Near an existing source, a significant impact may occur if that source averages, over three years, more than one confirmed odor complaint a year or three unconfirmed complaints a year.
• Valley Fever. The guidelines recommend no threshold; they list site factors and mitigation measures for the lead agency to weigh.

Greenhouse gases

For greenhouse gases the source is the district's CEQA page, not the 2003 guidelines. The page says that since the 2010 revisions to the CEQA Guidelines, lead agencies must decide whether a project's greenhouse gas emissions are significant and impose feasible mitigation, and it points them to CAPCOA's Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity.

What this means for a report

A Ventura County report compares operational ROC and NOx, area and mobile sources less any district-permitted equipment, with 25 lb/day each, or 5 lb/day in the Ojai Planning Area. Meeting or exceeding either is a potentially significant impact. Construction ROC and NOx are estimated separately and excluded from the operational significance comparison. Section 5.2 calls for construction mitigation when estimated ROC or NOx emissions from the anticipated heavy-duty construction equipment exceed 5 lb/day in the Ojai Planning Area or 25 lb/day elsewhere. The dust, toxics, odor, CO and AQMP tests apply according to their screening criteria and exemptions.

For emissions still significant after on-site measures, Section 7.5.3 describes paying into an off-site transportation demand management fund for three years of excess emissions, at $5.18 per pound of ROC and $7.54 per pound of NOx for projects completed in 2000, indexed to inflation. The funding calculation is made separately for ROC and NOx, and only the higher amount is used because the funded measures reduce both pollutants. The guidelines expect most projects to stay above the threshold even so, leaving the lead agency to weigh overriding considerations.

Where the thresholds are published

Ventura County Air Pollution Control District, Ventura County Air Quality Assessment Guidelines, adopted by the Ventura County Air Pollution Control Board; first publication April 1980, technical revision October 2003: Sections 1.1 and 2.2; Sections 3.2, 3.3.1, 3.3.2 and 3.4, with Figure 3-1 Ojai Planning Area; Section 4.2 and Table 4-1 1995 AQMP Population Forecasts; Sections 5.2 and 5.3; Sections 6.2 through 6.6, with Table 6-3 Project Screening Distances for Odorous Land Uses; Sections 7.4 and 7.5.3; Appendix F Project Screening Analysis Tables. District web page Air Quality Assessment for CEQA, last modified June 10, 2025.