The following acronyms are commonly referred to in the Philadelphia Diesel Difference website and materials.

AMS: Air Management Service is Philadelphia's regulating agency on air quality issues and part of the city's Health Department

B20: Most common biodiesel blend, comprised of 20% biodiesel and 80% petrodiesel

B100: Pure biodiesel that is nontoxic and biodegradable

CARB: The California Air Resource Board

CMAQ: Congestion Mitigation and Air Quality is a federal program to reduce transportation emissions in regions that are not in attainment of the Clean Air Act.

CO: Carbon Monoxide

CNG: Compressed Natural Gas

DOC: Diesel Oxidation Catalyst

DPF: Diesel Particulate Filter

DVRPC: Delaware Valley Regional Planning Commission is the area's metropolitan planning organization

EPA: U.S. Environmental Protection Agency

HAP: Hazardous Air Pollutant

HC: Hydrocarbons are a precursor to ozone and a serious air pollutant. Emissions result from incomplete fuel combustion and fuelevaporation.

IRT: Idle Reduction Technologies

LNG: Liquified Natural Gas (commonly called propane)

MDC: Mid-Atlantic Diesel Collaborative

MERCs: Mobile source Emission Reduction Credits

NMHC: Non-Methane Hydrocarbons

NOx: Nitrogen Oxides

PADEP: Pennsylvania Department of Environmental Protection

PDD: Philadelphia Diesel Difference

PM: Particulate Matter

PM10: Particulate matter with a mass median aerodynamic diameter of less than 10 micrometers. They are among the smaller particles, suspended in the air and easily inhaled into the deep lungs. Also known as "course" particulates.

PM2.5: Particulate matter with a mass median aerodynamic diameter of less than 2.5 micrometers. Also known as "fine" particulates.

RFP: Request For Proposals (when an entity with funds asks that applications be submitted for consideration)

SCR: Selective Catalytic Reduction

PPM: parts per million

ULSD: Ultra -Low Sulfur Diesel

VOC: Volatile Organic Compounds