Glossary

ASM

Accelerated Simulation Mode. ASM vehicle emissions tests are performed with a dynamometer and a five-gas analyzer. Typical vehicle speeds are 15-25 mph. During the inspection, the dynamometer simulates on-road testing (by electronically applying load to vehicles) to provide more accurate vehicle emissions readings. NOx (oxides of nitrogen) are only produced when vehicles are under load, so the dynamometer is required to measure NOx.

BAR

Usually refers to California's Bureau of Automotive Repair, long a leader in emissions control standards and specifications.

Basic test

The basic emissions inspection program utilizes the two-speed idle test. The basic emissions inspection program is used in moderate or marginal non-attainment ozone areas, and for vehicles that can not be tested on a dynamometer, such as vehicles equipped with Automatic Braking Systems (ABS) and permanent all-wheel-drive vehicles. (See two-speed idle definition).

Centralized

An emissions program where the state selects a vendor to oversee the operations of the inspection program, which includes project management, inspector training and certification, vehicle safety inspections, data management, customer service training, equipment installation, consumer literature, and testing of vehicles.

CS

Clean Screening, a remote sensing application that identifies the cleanest vehicles on-road without a station-based emissions test. Typically, a vehicle recording two clean readings within a specified time window is excused from its next scheduled inspection. The owner is notified by mail, and is entitled to submit a registration renewal without traveling to a testing facility.

Decentralized

An emissions program where the state permits independent inspection stations to purchase equipment from a certified vendor. Emissions tests are performed at the garage owner's facility.

Dynamometer

Also referred to as a "dyne". A treadmill-like device with two large rollers used with a five-gas analyzer to measure NOx. During the inspection, the dynamometer simulates on-road testing (by electronically applying load to vehicles) to provide more accurate vehicle emissions readings. NOx (oxides of nitrogen) are only produced when vehicles are under load, so the dynamometer is required to measure NOx.

Enhanced

The enhanced emissions inspection program is used in severe non-attainment ozone areas. The inspection measures NOx (oxides of nitrogen), one of the main gases found in ground level ozone, which can cause serious respiratory problems. Enhanced inspection programs conduct ASM or I/M 240 tests. (See ASM and I/M 240 definitions).

Gas Cap Test

The test consists of inserting the gas cap into an adapter and applying pressure to the gas cap. The test measures leak flow rate to determine whether the gas cap seal is sufficient to prevent gasoline from evaporating into the air from the vehicles tank.

GEI

Gross Emitter Identification, a remote sensing application that targets high pollutant-emitting vehicles for maintenance and repair. Typically, the owner of a vehicle identified as a high emitter receives a notice by mail requiring the vehicle to be re-inspected outside of its normal inspection cycle. The owner is required to make reasonable efforts to bring the vehicle into compliance with environmental standards.

HDD

Heavy Duty Diesel, large trucks and buses with diesel engines -- they are favored by commercial drivers because of their high fuel economy. Operators of such fleets have begun to choose remote sensing technology to monitor and analyze the emissions performance of their vehicles.

I/M

Acronym for Inspection and Maintenance

I/M 240

The I/M 240 test measures and records exhaust emissions in grams per mile for each pollutant while the vehicle is subjected to transient dynamometer loaded test cycle for 240 seconds. Transient emissions testing system includes a VMASS sample system, five-gas analyzer and dynamometer.

Low Profile Dynamometer

An above-ground dynamometer that is 8 inches in height.
NOx -- Oxides of Nitrogen. One of the main gases found in ground level ozone, which can cause serious respiratory problems.

OBD II

OBD II equipment performs inspections on vehicles equipped with On-Board Diagnostics (OBD) technology (1996 and newer vehicles). The OBD II test can determine whether there is a malfunction in the components that control exhaust/emissions through utilizing the vehicles computer system.

OREMS

On-Road Emissions Monitoring System, a protocol and associated performance standards for remote sensing vehicle emissions testing developed by the California BAR since 1995. These specifications have become the industry standard in the United States.

PE

Program Evaluation, a remote sensing application that characterizes in-use motor vehicle fleet exhaust emissions, identifying differences between fleets, and trends. Using one technique, program benefits are evaluated by testing a large sample of vehicles subject to inspection and maintenance and comparing results with those from a similar fleet not subject to inspection and maintenance.

Remote Sensing

Remote Sensing, when applied to vehicle emissions testing, refers to the measurement of vehicle exhaust emissions with roadside monitoring systems (known as remote sensing devices or RSDs), as the vehicle passes by without interfering with or altering the vehicle progress. Infrared (IR) and Ultraviolet (UV) light is directed across the road and passively reflected back to detectors that monitor light intensity at characteristic wavelengths. The amount of characteristic infrared or ultraviolet light absorbed is translated into the exhaust concentration of the three regulated pollutants of interest, carbon monoxide, hydrocarbons and nitrogen oxides.

RPM

Revolutions Per Minute

Transient Dynamometer

Emissions tests performed on a dynamometer according to various speeds and loads. During the inspection, the dynamometer simulates on-road testing, by electronically applying various speeds and loads to the vehicle depending on gross vehicle weight and engine displacement. Exhaust emissions are measured in volume rather than concentrations.

Two-Speed Idle

Typically, vehicles idle for 30 seconds, and are then accelerated to 2500 revolutions per minute for 30 seconds, and then back to idle for 30 seconds. A probe, placed in the tailpipe, collects information on the vehicles hydrocarbon, carbon monoxide, oxygen and carbon dioxide exhaust emissions concentration levels that are measured in a four-gas analyzer. The two-speed idle test is part of a basic emissions inspection program used in moderate or marginal non-attainment ozone areas, and for vehicles that can not be tested on a dynamometer, such as vehicles equipped with Automatic Braking Systems (ABS) and permanent All-Wheel Drive vehicles.

VMASS

The Constant Volume Sample System (VMASS) collects the exhaust then produces gas readings in volume measurement (i.e. grams per mile).