4.2 Cooking: Charbroiling, Deep Fat Frying, and Unspecified (Griddles)

Categories 29, 1710, and 1711

4.2.1 Introduction

Categories 29, 1710, and 1711 account for particulate matter (PM, PM10, and PM2.5) and total organic gas (TOG) emissions that result from cooking with charbroilers, deep fat fryers, and griddles at restaurants. The emissions result from the preparation of food for human consumption at eating establishments. Carbon dioxide (CO2), a greenhouse gas, is also emitted from cooking process in these three categories, but is presented separately in the BAAQMD Greenhouse Gas inventory.

Charbroilers can either be conveyorized or under-fire; both types generally use natural gas, however, under-fire charbroilers may use solid fuels, such as charcoal or wood. Deep-fat fryers may be either gas-fired or electric to heat the cooking oil used to cook the food. Griddles use an exposed metal plate, heated by either gas or electricity, to cook the food.

These categories do not include the products of combustion emissions from fuel usage (i.e. natural gas or solid fuels) at these establishments. Those emissions can be found in Categories 307, 1590, or 312.

4.2.2 Methodology

These categories are considered area source categories as they cover sources that are not explicitly permitted or individually cataloged by the District. Emissions for area source categories are determined using the formula:

Current Year Emissions = Base Year Emission X Growth Profile, and,

Base Year Emission = Throughput X Control Factor X Emission Factor

where,

  • throughput or activity data for applicable base year(s) is determined using a top-down approach (e.g. state-, national-level data);
  • emission factor is derived from general literature, specific literature and reports, and/or source testing results provided by Air District staff;
  • control factor (if applicable) is determined by District and state rules and regulations in effect;
  • and, historical backcasting and forecasting of emissions is based on growth profiles as outlined in the Trends section of this chapter

Emissions for categories 29, 1710, and 1711 were estimated by growing 2007 activity data according to population growth and applying established emissions factors based on equipment type and pounds of meat cooked. Detailed background on the determination of throughput, controls, and emission factors is provided in the following sections.

(a) Activity Data / Throughput

Throughput data for this category is derived from BAAQMD’s 2007 survey of total active restaurants 27 in combination with the estimated number of equipment type per restaurant and pounds of meat used per equipment type.

The District used a 1997 South Coast Air Quality Management District (SCAQMD) report, “Staff Recommendations Regarding Controlling Emissions from Restaurant Operations”, to estimate the number of charbroilers, deep fat fryers, and griddles used in the Bay Area. The SCAQMD report surveyed the type of equipment that was used in restaurant cooking operations in their district boundaries. This report found approximately 33% of the restaurants operates under-fired charbroilers, 4% operate chain-driven charbroilers, 62% operate deep fat fryers, and 52% operate griddles.

Pounds of meat per equipment type were estimated using numbers established in a report on charbroiling activity published by the Public Research Institute 28.

For the years following 2007, the activity level for this category is assumed to be proportional to the growth in population. Population forecasts as published by the Association of Bay Area Governments (ABAG) were used to estimated 2008 emissions and forward 29.

(b) County Distribution / Fractions

Emissions data is apportioned to each Bay Area county on the basis of year 2007 county-specific restaurant counts as collected by the District.

(c) Emission Factors

Emission factors developed by the University of California at Riverside 30 and the University of Minnesota were used to quantify the emissions each type of food cooked on charbroilers, deep fat fryers, and griddles produced.

(d) Control Factors

On December 5, 2007, the District adopted Rule 6-2, Commercial Cooking Equipment, to reduce particulate and VOC emissions from commercial cooking equipment. Effective January 1, 2009, chain-driven charbroilers that cook at least 400 pounds of beef per week are required to operate with a certified catalytic oxidizer to control emissions of both PM and VOC. Effective January 1, 2010, any newly installed under-fired charbroiler that has a grill surface area of at least 10 square feet and cooks at least 800 pounds of beef per week will be required to install a control device to reduce PM10 emissions to no more than 1 pound of PM10 per 1000 pounds of beef cooked. Effective January 1, 2013, any existing restaurant having an under-fired charbroiler that has a grill surface area of at least 10 square feet and cooks at least 800 pounds of beef per week is required to install a control device to reduce PM10 emissions by the same amount. These charbroilers (chain-driven and under-fired) must also be registered through the District.

(e) Speciation

The speciation applied to TOG to determine ROG is consistent with the size fractions of speciation profiles developed by the California Air Resources Board (CARB) and published on their emissions inventory web-page 31.The total organic gas (TOG) emitted from these three categories is considered to be all reactive (i.e. TOG equals ROG).

The inventory staff determines the PM speciation for a given category(s) can be based on data available from a handful of resources including PM speciation profiles made available by CARB32, US Environmental Protection Agency33, PM ratios generated from District-approved source tests, ratios used by other regional air quality agencies, or other relevant literature. Citations to data sources used to derive the PM speciation, where available, is included in this write-up. For this category(s), PM2.5 constitutes 77% of the total PM for this profile, while PM10 constitutes 100% of the total PM.

The PM emissions emitted from these three categories are particulate matter less than 10 microns in size (PM10) since it is assumed all particles larger than 10 microns are captured before the outside exhaust. A portion of these PM10 emissions are in the form of condensable vapors. Condensables are vapors in the gaseous form at entry into the ventilation hood, but may condense into particulate form (i.e. liquid or solid state) in the duct works, as it exits the exhaust fan, or in the atmosphere.

(h) Sample Calculations

Emissions were estimated as shown below:

  • \(\text{no.rest}\) = number of restaurants in Bay Area
  • \(\text{no.equip}\) = % restaurant per equipment (ex. 4% restaurants have one under-fired broiler)
  • \(\text{lb_per_equip}\) = lbs of meat cooked per equipment type per year (ex. 41,486 lbs of hamburger per under-fired broiler per year )
  • \(\text{e.f.}_{eq}\) = lb of pollutant per 1000 lbs of meat for equipment type; this a composite factor

\[ Emissions = \text{no._rest} * \text{no._equip} *\text{lb_per_equip}* \text{e.f.}_{eq} \]

4.2.3 Changes in Methodology

No major changes in methodology were made in this version of the base year emissions inventory as compared to the previous base year.

Updates to base year data from the previous inventories include the following:

  • Employment projection data from Plan Bay Area 2040, a publication by ABAG and the Metropolitan Transportation Commission (MTC), is used for emissions forecasting starting 2015

4.2.4 Emissions

A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.

4.2.6 Uncertainties

The most recent count of active restaurants in the Bay Area was last performed in 2007. Due to lack of more recent data, total count of each equipment type is based on population growth, however, this may not be a direct correlation. It is suggested that a new survey be taken to gain a more accurate count of restaurants and confirm how restaurant growth follows population.

4.2.7 Contact

Author: Ariana Husain

Reviewer: Michael Nguyen

Last Update: November 06, 2023

4.2.8 References & Footnotes

  1. Bay Area Air Quality Management District (BAAQMD). 2007. Staff Report: Regulation 6, Rule 2: Commercial Cooking Equipment↩︎

  2. Public Research Institute. 2001. Charbroiling Activity Estimation, Contract Num: 98-721↩︎

  3. Association of Bay Area Governments (ABAG). Forecasts and Projections. [Last Accessed 2023 Feb 22]. https://abag.ca.gov/our-work/land-use/forecasts-projections↩︎

  4. William A. Welch. 1997. Further Development of Emission Test Methods and Development of Emission Factors for Various Commercial Cooking Operations.↩︎

  5. CARB. 2022. ORGPROF; https://ww2.arb.ca.gov/speciation-profiles-used-carb-modeling↩︎

  6. PMSIZE. CARB 2022. https://ww2.arb.ca.gov/speciation-profiles-used-carb-modeling↩︎

  7. SPECIATE. USEPA 2022. https://www.epa.gov/air-emissions-modeling/speciate↩︎