O&M Operation and maintenance

OA Office of the Administrator

OAQPS Office of Air Quality Planning and Standards

OAQPSTTN Office of Air Quality Planning and Standards Technology Transfer Network

OAR Office of Air and Radiation

OARM Office of Administration and Resources Management

OC Office of the Comptroller

OCD Offshore and coastal dispersion

ODES Ocean Data Evaluation System

OE Office of Enforcement

OEL Occupational exposure limit

OER Office of Environmental Restoration

OERR Office of Emergency and Remedial Response

OGC Office of General Counsel

OGWDW Office of Groundwater and Drinking Water, USEPA

OHEA Office of Health and Environmental Assessments

OHM/TADS Oil and Hazardous Substances Technical Assistance Data System

OHS MSDS Occupational Health Services material safety data sheets

OIG Office of Inspector General

OIRM Office of Information Resources Management

OLS Online library system

OMB Office of Management and Budget

OMMSQA Office of Modeling, Monitoring Systems and Quality Assurance

OPP Office of Pesticide Programs

OPPE Office of Policy, Planning, and Evaluation

OPPT Office of Pollution Prevention and Toxics

OPPTS Office of Prevention, Pesticides and Toxic Substances

ORD Office of Research and Development

ORM Other regulated material

ORP Oxidation-reduction potential

OS Operations Support Directorate, FEMA; operating system

OSC On-scene coordinator

OSHA Occupational Safety and Health Administration

OSW Office of Solid Waste

OSWER Office of Solid Waste and Emergency Response

OTA Office of Technology Assessment

OTD Office of Technology Development

OUST Office of Underground Storage Tanks

OW Office of Water

OWP Office of Water Programs

OWPD Office of Waste Programs Enforcement

PA Preliminary assessment; public affairs

PAC Powdered activated carbon

PAI Performance audit inspection

PAPR Powered air-purifying respirator

PARC Public Access Resource Center

PAT Proficiency analytical testing

PB Polybutadiene or polybutylene

PBA Preliminary benefit analysis

PBZ Personal breathing-zone

PC Personal computer

PCB polychlorinated biphenyl

PCM Phase contrast microscopy

PCN Policy criteria notice

PCO Pest control officer

PCS Permit Compliance System

PEL Permissible Exposure Limit

PHPPO Public Health Practice Program Office, CDC

PHS U.S. Public Health Service

PHSA Public Health Service Act

PI Preliminary injunction; program information; propidium iodide; principal investigator

PIES Pollution Prevention Information Exchange

PIN Pesticide Information Network

PIO Public information officer

PIP Public involvement progam

PM Particulate matter

PNA Polynuclear aromatic

PO Project officer

POC Point of compliance; point of contact

POE Point of exposure, point of entry

POGO Privately-owned/government-operated

POR Program of requirements

POTW Publically owned treatment works

POU Point of use

PP Program planning

PPA Planned program accomplishment

PPIC Pollution Prevention Information Clearinghouse

PRA Paperwork Reduction Act

PRA Planned regulatory action

PRC Planning Research Corporation

PRP Potentially Responsible Party

PRV Pressure-reducing valve

PRZM Pesticide Root Zone Model

PS Point source; potentiodynamic scan

PSC Program site coordinator

PSFC Pipe section flow cell

PT Preparedness, Training and Exercises Directorate, FEMA

PUP Principle user processor

PVC Polyvinyl chloride

PWS Public water system; public water supply

PWSS Public water supply system

QA Quality assurance

QC Quality control

QAC Quality assurance coordinator

QA/QC Quality assistance/quality control

QAPP Quality assurance program plan; quality assurance project plan

QF Quality factor

QNCR Quarterly noncompliance report

QUAL2E Enhanced Stream Water Quality Model