June 15, 2010

Bay Area Air Quality Management District Adopts Groundbreaking Greenhouse Gas and Toxic Air Contaminant Thresholds

Holland & Knight Alert
Nicholas William Targ | Chelsea Maclean

On June 2, 2010, the Bay Area Air Quality Management District (BAAQMD), the Bay Area’s air pollution regulator, unanimously adopted stringent, new air quality thresholds under the California Environmental Quality Act (CEQA). The Thresholds, which are part of BAAQMD’s new Air Quality Guidelines, may set a precedent for air districts around the state and across the country, include new thresholds of significance aimed at limiting emissions of criteria air pollutants, greenhouse gasses (GHGs), toxic air contaminants (TACs), fine particulate matter (PM2.5) and odors. For these and other reasons described in this alert, the GHG and local community risks and hazards (i.e., TACs and PM2.5) thresholds are among the most restrictive of California’s 35 air districts – as well as among the most stringent in the nation.

The Guidelines also recommend that local governments establish community-wide plans that proactively address GHG emissions (Qualified GHG Reduction Strategy) and plans that address local community risk and hazard issues (Qualified Community Risk Reduction Plan) (collectively referred to herein as Qualified Plans). Once a municipality adopts a Qualified Plan with appropriate review under CEQA, air impacts from projects that demonstrate consistency will be considered less than significant, allowing for streamlined CEQA compliance.

The Guidelines, which replace BAAQMD’s 1999 CEQA guidance document, raised substantial controversy within both the public and private sectors, despite their unanimous adoption by BAAQMD’s Board of Directors. In particular, concerns have been raised that while the GHG thresholds are meant to encourage low GHG-emitting projects such as in-fill projects or transit-oriented development, the stringent local community risk and hazard thresholds (i.e., TACs and PM2.5 thresholds) may create the unintended consequences of making those same GHG-thrifty, in-fill developments more challenging to site and may also raise the cost to develop affordable housing in urban areas. The Guidelines’ recommendation to establish community-wide Qualified Plans to limit or mitigate GHG emissions and local community risk and hazard issues is, in part, an effort to limit regulatory burden, while making a positive contribution to environmental quality.

In recognition of the sweeping changes affected by the Guidelines, the adopting Resolution No. 2010-06 states that it is the policy of BAAQMD that lead agencies in the Bay Area apply the CEQA thresholds of significance, except for the risk and hazard thresholds, for Notices of Preparations (NOPs) issued, and environmental analysis that began, on or after June 2, 2010. The risk and hazards thresholds apply to NOPs issued, and environmental analysis begun, after January 1, 2011. Please click here to see BAAQMD Resolution 2010-06.

The following discussion highlights the new thresholds for GHG and local community risks and hazards impact (TACs and PM2.5) emissions.

Greenhouse Gas Emissions

The Guidelines establish that GHG emissions and global climate change represent cumulative impacts. The BAAQMD Proposed Thresholds of Significance Report (Report) states that “[i]f left unchecked, GHG emissions from new land development in California will result in a cumulatively considerable amount of GHG emissions and a substantial conflict with the State’s ability to meet the goals within AB 32[, the Global Warming Solutions Act of 2006].” Based on the findings in the Guidelines and the Report, BAAQMD’s GHG thresholds are aimed at helping lead agencies comply with AB 32. While lead agencies are not legally required to rely on these thresholds, courts are expected to give deference to and rely on the rigorous thresholds, creating greater regulatory clarity in the absence of definitive case law or hard-and-fast rules for GHG analysis under CEQA.

The Guidelines provide significance thresholds at both the “project” and plan” levels. “Projects” include both land use development projects (e.g., residential, commercial, industrial, and public land uses and facilities) as well as stationary source projects (i.e., land uses that accommodate processes and equipment that require an air district permit to operate). “Plans” include long-range planning documents such as general plans and redevelopment area plans.

For land use projects, the Guidelines, first, recommend comparison of project attributes with conservative screening criteria. If a project has GHG levels less than the screening criteria, no further analysis is required; however, only a small number of projects are likely to meet these screening criteria. Examples of projects that the Guidelines establish as meeting the screening criteria include the following:

  • 55 single-family dwelling unit project
  • 15,000 square foot free-standing discount store
  • 53,000 square foot office building

There are no screening criteria for stationary source projects or plans.

Second, for projects and plans that do not meet the screening criteria, the Guidelines state that the lead agency must consider whether direct and indirect emissions, as well as emissions reducing features (e.g., emissions reductions from design features, local development requirements), meet specified thresholds of significance. The Guidelines also provide recommended mitigation measures to reduce the project’s GHG emissions. If the mitigated annual emissions of operational-related GHGs exceed the thresholds, the proposed project or plan results in a cumulatively significant impact to global climate change. The specific thresholds are summarized as follows:

Land Use Development Project

  • Complies with a Qualified GHG Reduction Strategy;
  • Emits less than 1,100 metric tons of CO2e per year (roughly 55 dwellings); or
  • Emits less than 4.6 metric tons of CO2e per service population member (i.e., residents and employees) per year

Stationary Source Project

  • Emits less than 10,000 metric tons of CO2e per year


  • Complies with a Qualified GHG Reduction Strategy; or
  • Emits less than 6.6 metric tons of CO2e per service population member per year1

Given the stringency of the GHG thresholds, the Guidelines are expected to incent local governments to adopt Qualified GHG Reduction Strategies, consistent with AB 32 goals. A GHG Reduction Strategy must satisfy several specified elements that are consistent with the “Plans for the Reduction of Greenhouse Gas Emissions” described in CEQA Guidelines section 15183.5. After adoption of a GHG Reduction Strategy, GHG impacts from projects or plans that are consistent with the Strategy will be considered less than significant. In that instance, environmental review would be streamlined in the following ways: (1) mitigation, over what is already incorporated proposed for the project, would not be required; (2) an Environmental Impact Report would not be required, as long as the project will not cause any other significant impacts; and (3) a Statement of Overriding Considerations would not be required.

Local Community Hazards and Risks (Toxic Air Contaminants and Fine Particulate Matter) Thresholds

The Guidelines also establish new thresholds and methodologies for assessing local community risk and hazard impacts from TACs and PM2.5. Among other things, the Guidelines:

  • set numerical screening criteria and threshold for PM2.5 and risk thresholds for TACs
  • require, in general, evaluation of TAC and PM2.5 emissions within a 1,000 foot radius of the proposed project; this requirement applies both to projects that site new sensitive receptors (e.g., residential developments, hospitals and playgrounds) as well as stationary source projects (e.g., distribution centers and facilities with back-up generators) that are proposed within 1,000 feet of a sensitive receptor

The local community risk and hazard impacts assessment applies to both project-level and plan-level projects. Cumulative impacts, that is, the combined risk from all nearby TAC sources, must also be considered.

Like the Guidelines’ approach to assessment of GHG impacts, the local community risk and hazard impacts analysis follows a two-step approach. Under the first step, project proponents compare data pertaining to local TAC and PM2.5 sources (the Guidelines state BAAQMD will make this data available) to the Guideline’s significance thresholds. If a project meets the thresholds, no further analysis is required.

If a project exceeds the thresholds under the screening assessment, under the second step, the project’s modeled data may be used and compared to the GHG Guidelines’ thresholds. Modeled data are based on site-specific conditions and could include, among other things: (1) prevailing wind directions; (2) regulatory requirements in place that establish mandatory reductions in diesel emissions from trucks; and (3) site specific traffic characteristics (e.g., the height of the roadway and the composition of vehicles on the roadways). Each of these variables may have a significant effect on actual site specific impacts and, consequently, the ability of a project to meet the Guidelines’ thresholds.

Thresholds of significance for project-level impacts are as follows:

For plan-level impact analysis, the Guidelines require certain components to be included in a plan as a means to gauge significance, rather than imposing numerical thresholds. Specifically, thresholds of significance for plan-level impacts include the following:

1) The land use diagram (e.g., for general plans and redevelopment area plans) must identify special overlay zones covering:

  • existing and planned sources of TACs and PM2.5; and
  • at least 500 feet (or air district-approved modeled distance) on each side of all freeways and high-volume roadways; and

2) The land use plan must identify goals, policies, and objectives to minimize potentially adverse impacts. The Guidelines recommend that the Lead Agency should refer to Air Quality and Land Use Handbook: A Community Health Perspective (CARB 2005) when evaluating whether the proposed plan includes adequate buffer distances between TAC sources and sensitive receptors.

The Guidelines establish a variety of mitigation measures for projects and plans that do not meet the Guidelines’ thresholds. For project-level mitigation, approaches range from establishing set-backs to planting tiers of trees such as redwood, deodar cedar and live oak, which the Guidelines state have been found to remove 65 percent to 85 percent of PM2.5 under certain conditions. Identified plan-level mitigations include improvements to circulation, buffering of land uses and adoption of a comprehensive Community Risk Reduction Plan, among others.


BAAQMD’s new Guidelines in the short- to intermediate-term will create new regulatory hurdles and, potentially, design challenges for large-scale and urban in-fill development projects. For projects that trigger significance, options for streamlined environmental review will be precluded unless addition mitigations can be developed. In the longer term, the Guidelines’ recommendation to develop Qualified Plans may alleviate the Guidelines’ regulatory burden and achieve improved environmental quality.




1 The Guidelines provide that this efficiency standard should only be applied to general plans. Other plans (e.g. specific plans, congestion management’s plans, etc.) should use the project-level threshold of 4.6 CO2e/service population/year. Guidelines at 2-7. Regional plans are also treated differently and are subject to a threshold of “no net increase in emissions.” Guidelines at 9-1.

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