9.1 Lawn and Garden Equipment
Categories 1647, 1648, 1649, 1650, and 1651
9.1.1 Introduction
Categories 1647, 1648, 1649, 1650, and 1651 account for emissions (NOx, CO, PM, PM10, PM2.5, ROG, SO2, and TOG) from lawn, garden and other general utility equipment, powered by two and four stroke gasoline engines of less than 20 horsepower and diesel engines. Two-stroke engines have several attributes that are advantageous for applications such as leaf blowers. The two-stroke engines are lightweight and operate in multi-position, allowing for great flexibility in equipment applications. Typical two-stroke engines feed fuel/oil mixture into combustion chamber. A major disadvantage of two-stroke engines is high exhaust emissions. The major pollutants from a two-stroke engines are: oil-base particulates, reactive organics (a mixture of burned and unburned hydrocarbons), and carbon monoxide. Lawn, garden and other diesel equipment includes products such as walk behind mowers, garden tractors, hedge and lawn trimmers and leaf blowers. General utility equipment includes chain saws, generators, compressors, pumps, welding machines, grinders and shredders.
9.1.2 Methodology
The Lawn and Garden Equipment emissions are derived by California Air Resources Board (CARB) inventory staff. 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. BAAQMD staff export the emissions data directly from CEPAM into the District’s Base Year inventory package. This calculation approach and collection of categories are internally termed as “CARB Source Categories”.
This base year inventory uses the 2016 CEPAMv1.05341 to estimate emissions from “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.
9.1.3 Changes in Methodology
Emissions data were obtained from the CARB’s 2016 CEPAMv1.051. In comparison, the emissions in the previous inventory methodology involved area source categories derived from the CARB’s OFFROAD2007 model.
9.1.4 Emissions
A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
9.1.5 Trends
(a) Historical Emissions / History
Prior to the 1999 base year emissions, the methodology for the lawn and garden equipment was based on the published report “Report on Utility Equipment Emissions in the State of California” by Booze, Allen, and Hamilton (BAH). For each type of equipment, estimates were made of the in-use population in California and percentage of use for residential and commercial applications. This was based on national equipment sales data, interviews with domestic and foreign manufacturers. Average HP rating, hourly use and load factor for each type of equipment were estimated for both commercial and residential applications.
California Air Resources Board (CARB) developed the Off-road vehicle emission inventory (OFFROAD2007) model to estimate emissions from off-road motor vehicles for all counties and air basins in California. The OFFROAD2007 model contains a more comprehensive list of equipment from a wider range of categories compared to BAH. The model adds an inventory estimate for engines powered by diesel fuel, compressed natural gas (CNG) and liquid petroleum gas (LPG) which were not previously accounted for. The criteria and GHG emission data for lawn, garden and utility equipment categories in the Bay Area were obtained from the CARB’s OFFROAD2007 model.
(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).
(c) Control
In December of 1990, the CARB adopted two levels of emission standards for small off-road engines. The first phase of standards (Tier 1) was implemented in 1995 342 and Tier 2 standards are scheduled for implementation in 1999. The deterioration rates for 4 stroke Tier 1 engines were derived from data supplied by engine manufacturers. Since engines meeting Tier 2 standards are not yet available, engineering judgment was used to estimate the effect of the more stringent standards. The first set of regulations for utility engines came into effect on January 1, 1994. These were in the form of specific emission standards for different sizes and types of engines used in this type of equipment. More stringent standards came into effect in January 1999.
Gov. Newsom signed a new law (AB1346 343) on October 9, 2022 to ban the sale of new gas-powered equipment using small off-road engines, a broad category that includes generators, lawn equipment, and pressure washers beginning in 2024. This bill orders CARB to regulate new small off-road engines (SOREs), used primarily for landscaping, to be zero-emission.
9.1.6 Uncertainties
The estimated Lawn and Garden Equipment emissions for Solano and Sonoma counties under District’s jurisdiction may contribute to an increased uncertainty of the Bay Area Off Road emissions.
9.1.7 Contact
Author: Michael Nguyen
Reviewer: Ariana Husain
Last Update: November 06, 2023
9.1.8 References & Footnotes
CARB. 2016. California Emissions Projection Analysis Model (CEPAM) inventory, https://www.arb.ca.gov/app/emsinv/2016ozsip/2016ozsip/fcemssumcat_2016o3sip105.php↩︎
CARB. 1995. California Exhaust Emission Standards and Test Procedures For 1995 and Later: Small Off-Road Engines. https://ww2.arb.ca.gov/sites/default/files/barcu/regact/sore/test_fin.pdf?_ga=2.97100055.962285900.1646782104-423543219.1584725377↩︎
CA. 2021. CA Assembly Bill No. 1346, https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202120220AB1346↩︎