6.21 Printing

Categories 108, 109, 110, 112, 115, 116, 1898, 1899, and 1900

6.21.1 Introduction

The categories 108, 109, 110, 112, 115, 116, 1898, 1899, and 1900 account for emissions from graphic arts printing operations. The emissions consist of both point and area source emissions.

The graphic arts printing operation uses a variety of inks, materials, coatings, fountain solutions, blanket washes, makeup solvents, solubilizers, and clean-up materials. Organic compounds are contained in these products and are emitted into the atmosphere during the printing operations.

Graphic arts printing consists of five primary types of printing operations: Gravure, Flexographic, Letterpress, Lithographic, and Screen. Of the five types of operations, only four major types of printing processes are involved: gravure, letterpress, lithographic, and screen (flexographic printing is simply a modified form of letterpress). These printing processes are briefly described below.

  1. Gravure Printing (category 108) – a type of printing operation whereby ink is transferred from a plated minute etched well to a substrate that is supported by an impression roller. Ink excess is removed by a doctor blade;
  2. Flexographic Printing (category 109) – a printing operation that utilizes a “rolling technique” to apply words, designs, and pictures to the substrate. The image carrier is made of either a rubber elastomer or a similarly related elastomeric material;
  3. Letterpress Printing (category 110) - a printing operation whereby ink is transferred to the paper via an image surface. The image area is raised relative to the non-image area;
  4. Lithographic Printing (category 112 - Point Sources, and category 1898 - Area Sources) – a printing operation whereby printing of image and non-image areas are carried out on the same plane;
  5. Screen Printing (category 115 - Point Sources, and category 1899 - Area Sources) – a printing operation whereby printing ink passes to a web or a fabric from which a refined form of stencil is applied.

In this emission inventory, the District also accounts for small in-house printing emissions (category 116 - Point Sources, and category 1900 - Area Sources). Small in-house emissions is comprised of various small in-house operations that may use intaglio, ink jet, and xerographic prints in the printing processes.

6.21.2 Methodology

The printing categories reflected herein covers emissions from both District permitted (point) and non-permitted (area) printing sources.

Point Sources

Point Sources are operations that emit air pollution into the atmosphere at a fixed location within a facility, for which the Air District has issued a permit to operate, e.g. refinery cooling towers. These could also be a collection of similar equipment / sources located across multiple facilities, e.g. reciprocating engines.

During the permit to operate (PTO) issuance process, the BAAQMD collects information from the operating facility and/or determines from published literature, e.g. EPA’s AP-42, characteristics of a source including maximum throughput, emission factors for emitted pollutants, and control factors associated with downstream abatement devices. These characteristics are then stored for future use in the BAAQMD’s internal database. Facilities that hold a permit to operate are required to renew this permit periodically (this period varies based on facility and source type). Upon renewal, the facilities are requested to provide any updates to source characteristics as well as the source throughput for the last 12 months. This throughput, in combination with the emission factors and controls factors stored in the internal database, are used to estimate annual emissions at the source level. These source level emissions are then sorted and aggregated into categories. Further speciation and quality assurance of emissions are performed as a part of the inventory process. The BAAQMD staff also 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), which ensures consistency in the annual emissions reporting process (CEIDARS) to California Air Resources Board. The last part of the inventory development process includes forecasting and back casting, and aggregation into sub-sectors and sectors for documentation purposes. For those years where no data is available, emissions data are backcasted to year-1990, as well as forecasted to year-2040 using either interpolation or another mathematical approach (see Trends section). Finally, emissions trends spanning from year 1990-2040 for each category and pollutant are evaluated for anomalies that are then investigated and addressed.

Categories 108, 109, 110, 112, 115, and 116 are considered point source categories and follow the above methods for emissions estimates. To limit and reduce emissions from these categories, District’s Regulation 8, Rule 20, Graphic Arts Printing and Coating Operations Rule 243 regulates organic compound emissions from various printing manufacturers in the Bay Area. The Rule was originally adopted in April 1980 and has received various amendments and revisions since that time.

Area Sources

Categories 1898 through 1900 are considered an area source category since they cover facilities / emission sources that are not directly permitted by the District, and hence not systematically cataloged. 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

More details on throughput, county distribution, emission factors and controls is provided in the following subsections. Emissions from printing operations in non-permitted industries are usually estimated at the unit of a geographical area, e.g., county. Non-permitted industries include primarily small printing operations or exempt operations that either do not meet District’s threshold level to be permitted or contain special conditions to be granted an exemption from the requirement of a permit to operate by the District.

(a) Activity Data / Throughput

Point Sources

Throughputs of point sources are collected as referenced in the Methodology section of this chapter.

Area Sources

Emissions from small, unpermitted printing facilities are estimated based on data gathered through the U. S. Department of Commerce’s publication titled, “Printing Ink Manufacturing: 2002”244. Similarly to permit data, adjustments for area sources were made to include emissions from cleaning solvents such as fountain solutions, preparation, and cleanup solutions. This is in addition to organic emissions from printing operations where the bulk of the emissions are collected from the printing sources. The cleanup solutions are used to clean and prepare equipment and materials for printing jobs.

(b) County Distribution / Fractions

For point sources, the physical location of each printing company as reported in the District’s permitting system was used to distribute emissions for each county.

(c) Emission Factors

Point Sources

Emission factors for point sources are collected and used as referenced in the Methodology section of this chapter.

Area Sources

The county distribution is based on printing manufacturers data collected by the US Census Bureau 245, which includes the number of printing establishments in the county, the employee size, and annual payroll from various printing manufacturers that is searched for the nine different counties of the District. The derived county fraction data was used to distribute emissions for each county.

(d) Control Factors

The Bay Area’s graphic arts printing industry are regulated under Regulation 8, Rule 20 1. This regulation was adopted in 1980, amended in 1984, 1985, 1989, 1993, 1995, 1997, 1999, and 2008. The Rule requires low solvent usage on inks and coatings, volatile organic compound (VOC) limits of products and fountain solution, deployment of approved emission control system, and compliance schedules. The rule has resulted in reduced emissions for most of these categories.

(e) Speciation

The ROG/TOG ratios applied to this group of related categories are based on an Air District internal speciation profile. Multiple data sources have been used for developing speciation profiles, such as Air District-approved source tests, TOG speciation ratios used by other regional air quality agencies, and relevant literature including latest speciation profiles developed by CARB246 and the US Environmental Protection Agency247. For this group of categories, ROG constitutes 100% of TOG. Further assessment and improvement of ROG/ TOG speciation profiles has been planned in future inventory updates.

6.21.3 Changes in Methodology

There are no changes in the methodology to estimate emissions in the current base year inventory compared to the previous base year inventory (year 2011).

6.21.4 Emissions

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

6.21.6 Uncertainties

For point sources, throughputs of these categories are reported by all printing manufacturing facilities via the BAAQMD permit system requirement on a year by year basis and are assumed to reflect the most current data available at the time. Throughput data that are taken based on source test is considered the most accurate, followed by engineering calculations such as mass/material balance.

For both point and area source emission factors, the main uncertainty in the updated methodology arises from the use of emission factors for certain categories that remain constant over several decades although technological controls may have been applied at facilities. Additionally, the emission factors themselves are seldom verified and validated against measurements, in part due to the difficulty in measuring fugitive emissions from area sources.

6.21.7 Contact

Author: Tan Dinh

Reviewer: Abhinav Guha, Yuan Du

Last Update: November 06, 2023

6.21.8 References & Footnotes

  1. BAAQMD. 2008. Reg 8-20. https://www.baaqmd.gov/rules-and-compliance/rules/reg-8-rule-20-graphic-arts-printing-and-coating-operations↩︎

  2. U.S. Department of Commerce. Printing Ink Manufacturing Economic Census 2002. [accessed 2023 March 13]. https://www2.census.gov/library/publications/economic-census/2002/manufacturing-reports/industry-series/ec0231i325910.pdf↩︎

  3. U.S. Census Bureau. Data ; [accessed 2023 March 13]. https://data.census.gov↩︎

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

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

  6. Plan Bay Area 2040. ABAG 2017. http://2040.planbayarea.org/files/2020-02/Final_Plan_Bay_Area_2040.pdf↩︎