Bay Area Air Quality Management District

The Bay Area Air Quality Management District covers the nine Bay Area counties, in whole or in part. Its 2022 CEQA Air Quality Guidelines, published April 2022, put thresholds, screening tables, CalEEMod instructions, and health risk methods in one package. The chapters are posted individually and revised in place, so the district's page carries the current revision of each. The air quality thresholds date from June 2, 2010 and were carried forward unchanged. The greenhouse gas thresholds were rewritten and adopted April 20, 2022. An April 2025 supplement is limited to environmental justice implementation examples. The guidelines describe themselves as nonbinding recommendations to lead agencies.

Criteria pollutant thresholds, Table 3-1

Pollutant	Construction, average daily (lb/day)	Operational, average daily (lb/day)	Operational, maximum annual (tons/yr)
ROG	54	54	10
NOx	54	54	10
PM10	82 (exhaust only)	82	15
PM2.5	54 (exhaust only)	54	10
PM10 and PM2.5 fugitive dust	Best management practices	None	None
Local CO	None	9.0 ppm 8-hour average, 20.0 ppm 1-hour average

There is no SOx threshold. Construction is compared on average daily emissions only; operations on both average daily and annual.

How the comparison is made

• Construction. Average daily emissions are computed for each construction year based on the number of working days in that year; in practice the year's tons, times 2,000, divided by that year's working days. A project that finishes in under a year is annualized over the actual days of peak activity, not the full year.
• Operations. Total annual emissions divided by 365 for land uses that operate most days. A school or arena divides by the days it actually operates.
• Overlap. Where a phased project operates while construction continues, construction exhaust is combined with operational emissions for every overlapping phase.
• Fugitive dust. No number. Construction dust is less than significant only when the project implements every basic best management practice in Table 5-2. Enhanced practices in Table 5-3 are strongly encouraged near schools and homes.
• Model. The current version of CalEEMod. Appendix D, Using CalEEMod for Bay Area Projects, is written to version 2022.1 and its screenshots to 2022.1.1.0.
• Screening. Chapter 4, Table 4-1 gives single land use sizes below which construction and operational criteria pollutant emissions are presumed below the thresholds. Mixed use projects use the district's separate screening tool because the sizes are not additive.

The nine basic construction practices, Table 5-2

1. Water all exposed surfaces twice a day.
2. Cover haul trucks carrying soil, sand, or other loose material off site.
3. Remove visible trackout on adjacent public roads with wet power vacuum sweepers at least once a day. No dry power sweeping.
4. Limit vehicle speeds on unpaved roads to 15 mph.
5. Pave roadways, driveways, and sidewalks as soon as possible; lay building pads as soon as possible after grading unless seeding or soil binders are used.
6. Suspend excavation, grading, and demolition when average wind speed exceeds 20 mph.
7. Wash off trucks and equipment, including tires, before they leave the site.
8. Treat unpaved access roads 100 feet or more from a paved road with 6 to 12 inches of compacted wood chips, mulch, or gravel.
9. Post a publicly visible sign with the lead agency contact for dust complaints, who responds within 48 hours, and the district's complaint line.

Greenhouse gas thresholds, Table 3-2

A land use project must satisfy A or B.

A. Project design elements, all of them:

• 1(a) No natural gas appliances or natural gas plumbing, residential and nonresidential.
• 1(b) No wasteful, inefficient, or unnecessary energy use under Public Resources Code 21100(b)(3) and CEQA Guidelines 15126.2(b).
• 2(a) Project vehicle miles traveled below the regional average consistent with the current Scoping Plan, currently 15 percent, or a locally adopted SB 743 target: residential 15 percent below existing VMT per capita, office 15 percent below existing VMT per employee, retail no net increase in existing VMT.
• 2(b) Compliance with the off-street electric vehicle requirements of the most recently adopted CALGreen Tier 2.

B. Consistency with a local GHG reduction strategy that meets CEQA Guidelines 15183.5(b).

There is no tonnage threshold for land use projects. Construction GHG emissions are disclosed. Stationary sources permitted by the district are held to a separate bright line of 10,000 metric tons CO2e per year under Chapter 6.4, and a project with both a building and permitted equipment answers both.

Health risk, odor, and other thresholds

Impact	Individual project	Cumulative, all sources within 1,000 feet
Excess cancer risk	More than 10 in a million	More than 100 in a million
Non-cancer hazard index	More than 1.0, chronic or acute	More than 10.0, chronic
PM2.5 concentration	Increase above 0.3 micrograms per cubic meter annual average	Above 0.8 micrograms per cubic meter annual average

Either test is also met by compliance with a qualified community risk reduction plan. Construction uses the operational values.

• Odor. Five confirmed complaints per year averaged over three years, which Chapter 5 says is not an absolute threshold, since wind direction, few nearby receptors, or seasonality can suppress complaints. Table 5-4 adds screening distances by facility type, for example two miles for a wastewater treatment plant, refinery, asphalt batch plant, or rendering plant and one mile for a transfer station, composting facility, or coffee roaster.
• Local CO. Screened out when the project is consistent with the congestion management program and does not raise any intersection above 44,000 vehicles per hour, or 24,000 where mixing is limited, such as a tunnel, parking garage, or street canyon.
• Accidental release. Storing or using acutely hazardous materials near receptors, or siting receptors near them, is significant; the guidelines point to Emergency Response Planning Guidelines level 2.

Where the thresholds are published

Bay Area Air Quality Management District, California Environmental Quality Act Air Quality Guidelines, April 2022: Chapter 3 Thresholds of Significance (Tables 3-1 and 3-2), Chapter 4 Screening, Chapter 5 Project-Level Air Quality Impacts (Tables 5-2 through 5-4 and the averaging method), Chapter 6 Project-Level Climate Impacts, Appendix D Using CalEEMod for Bay Area Projects, Appendix E Recommended Methods for Screening and Modeling Local Risks and Hazards. The April 2025 California Environmental Quality Act Guidelines Supplemental covers environmental justice practice only.