10.14 Consumer Products
Categories 2370, 2371, 2372, 2373, and 2374
10.14.1 Introduction
These categories account for organic gas (TOG and ROG) emissions from the use of consumer products such as hair spray, shaving cream, deodorant, charcoal lighter fluid, etc.
10.14.2 Methodology
For certain categories in the base year inventory, emissions data are derived by inventory staff of the state’s chief air quality regulatory agency, the California Air Resources Board (CARB). This significant emissions dataset, sorted by county, is published every few years and is a product of the State Implementation Plan (SIP) emissions document formally known as the California Emissions Projection Analysis Model (CEPAM) inventory 480. For related sets of categories, such as airport ground support equipment (GSE), ships, structures coatings etc., where independent data collection and derivation of emissions are both cost- and time-prohibitive and likely a redundant effort, BAAQMD staff export the emissions data directly from CEPAM into the District’s Base Year inventory package. This calculation approach and collection of categories is internally termed as “CARB Source Categories”.
The CEPAM provides historical emissions as well as forecasts emissions for major emission source classifications including –
- on-road mobile sources [from Emissions Factor (EMFAC) model],
- off-road mobile sources (OFFROAD model), and,
- stationary and areawide sources - For these major source classifications, CEPAM combines facility level /area source emissions data reported to the California Emissions Inventory Development and Reporting System (CEIDARS) for multiple years by various regional air quality agencies (including the BAAQMD).
This base year inventory uses the 2016 CEPAMv1.05 to estimate emissions for “CARB Source Categories”. This version of the CEPAM derives emissions from a 2012 base year inventory and contains backcasts and forecasts from year-2000 to year-2035. All applicable regulatory and technological controls are assumed to be built into the CEPAM dataset during CARB staff’s inventory computation work. After the emissions data are exported, the inventory for CARB Source categories is taken through a quality assurance (QA) process.
In the QA process, BAAQMD staff perform a systematic crosswalk between CEPAM’s source category classification (Emission Inventory Code - EICs) and the District’s source category classification (category identification number - cat_ids). Based on the scope of emissions covered, individual EIC or a group of EICs are mapped to a single cat_id. This process also addresses issues when cat_ids have no matching EICs or there are discontinued EICs that need to be investigated. Following this, emissions data are backcasted to year-1990, as well as forecasted to year-2040 using certain mathematical methods, as described in the Trends section. Finally, the emissions trends spanning from year 1990-2040 for each category and pollutant are evaluated, and CARB staff are consulted for explanation of any observed anomalies in trends.
10.14.3 Changes in Methodology
Changes to methodology are those noted in the CARB documentation for consumer products and are noted below for reference:
• A broader application of Fate and Transport adjustments,
• Use of a higher market adjustment factor for one EIC (the “No Rinse Shampoo” category),
• A refinement of Fragrance Speciation, and
• The use of an alternative growth surrogate for Personal Care Products
10.14.4 Emissions
Emissions for consumer products are based on sales of consumer products. Estimates by county are based on population per county.
A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
10.14.5 Trends
(a) Historical Emissions / History
Three different methods are used for backcasting to project historical emissions prior to year-2000 going back to year-1990, which is the starting year of the current base year inventory (referred to as BY2015). Following preliminary evaluation of the data available for initial years (post-year 2000) in the CEPAM inventory, BAAQMD staff recommends a backcasting approach. The default backcasting approach is defined by a formula here –
\[ \begin{eqnarray} \text{BY2015 emissions for year X for county Y} = \text{BY2011 total emissions for year X} \\ \\ \times \dfrac{\text{BY2015 year-2000 emissions}}{\text{ BY2011 year-2000 emissions}} \\ \\ \times \dfrac{\text{county Y fraction}}{\text{ fractional total}} \end{eqnarray} \]
This calculation is referred to as the BY2011 scaling method (based on the previous base year inventory). The second calculation approach is to derive the linear regression best fit of the year 2000-2008 CARB Sources emissions data for a category, species, and county, and extrapolate that data back in time. If this backcasting results in negative emissions prior to a certain year, the lowest positive emission value is held constant from that particular year back to year-1990. The third possible calculation approach is to use a specific growth profile for the category, provided by the in-house staff expert. These custom growth profiles are often derived from surrogate data provided by another agency or resource, or available activity data that is assumed to scale with the emissions for that specific CARB Source category.
For all consumer product categories, the BY2011 scaling method is used to derive emissions for years 1990 through 1999.
(b) Future Projections / Growth
Emissions forecasting was done by holding the year-2035 emissions data constant through and up to year-2040. For CARB Sources, emissions are forecasted by CARB staff by applying growth profiles to the base year-2012 inventory data (see above in ‘Methodology’ section). For Consumer Products, growth is based on population.
10.14.6 Uncertainties
In recent studies it has been found that emissions resulting from the use of consumer products may have a substantial contribution to overall organic emissions in a region. This new research is currently being reviewed and is slated to be incorporated in future BAAQMD inventory work.
In most cases average VOC lb/gal factors are used to estimate emissions for a consumer product group. This could lead to either under or over estimation of emissions. Factors specific to the product used would make estimates more accurate but would be very cumbersome to collect. For the most part, CARB is working on refining these average factors to better fit the product category.
Please refer to CARB’s CEPAM Inventory documentation for more information.
10.14.7 Contact
Author: Ariana Husain
Reviewer: Michael Nguyen
Last Update: November 06, 2023
10.14.8 References & Footnotes
CARB. Criteria Pollutant Emission Inventory Information (CEPAM) . [accessed 2023 Mar 13]. https://ww2.arb.ca.gov/criteria-pollutant-emission-inventory-data↩︎