Hydrocarbon and Carbonyl Monitoring

This page last reviewed December 10, 2010

The California Air Resources Board began a routine seasonal sampling program in 1989 to gather information about non-methane hydrocarbon (NMHC) species in the high ozone areas of the state.  Beginning in 1994, Federal regulations require states to establish photochemical assessment monitoring stations (PAMS) as part of their State Implementation Plan monitoring networks in ozone nonattainment areas classified as serious, severe, or extreme.  The PAMS program is intended to supplement ozone monitoring and add detailed sampling for it's precursors.   The current ozone nonattainment areas subject to regulation in California are: South Coast (Los Angeles, Riverside, Orange, San Bernardino), Sacramento, San Diego, San Joaquin Valley, Santa Barbara, Mojave Desert, and Ventura.  The local air pollution districts in the affected areas are full participants in the PAMS monitoring activities.  ARB does not currently operate PAMS sites.

Measurements made at the PAMS sites include ozone, oxides of nitrogen, 56 target hydrocarbons and at least two carbonyls (formaldehyde and acetaldehyde), and surface and upper air meteorology.  Most PAMS sites obtain measurements on 3-hour basis during the summer ozone season. 


Sampling / Monitoring 

Monitoring Activities summarizes the network and the monitoring methods for nonmethane hydrocarbons, methane, and total hydrocarbons monitoring activities.

California PAMS Network 2000  (Acrobat, 20KB)  summarizes the California PAMS network for hydrocarbons, carbonyls, ozone, oxides of nitrogen, and meteorology.  Monitoring for hydrocarbons and carbonyls begins in June or July and continues through September. 


Laboratory Analysis
The NMHC air samples are collected in stainless steel canisters and analyzed in the laboratory by two separate gas chromatography (GC) methods.  A speciated GC analysis is performed on every sample to identify and quantify each target hydrocarbon (speciated NMHC).  A second aliquot of the air sample is analyzed in another GC configured to measure the total mass of all target and non-target hydrocarbons (total NMHC).  The carbonyl air samples are collected in adsorbent cartridges and are analyzed by high performance liquid chromatography. 

Laboratory Standard Operating Procedures
Each method used to generate laboratory data has a written SOP.  These procedures are followed each time the method is used to produce data for record.  The following is a list of the SOPs used currently in the analysis of PAMS precursors.  For a copy of these SOPs, please contact Kathy Gill at kgill@arb.ca.gov or visit the Laboratory SOP Page.  

  • SOP MLD022 - Determination of Carbonyl Compounds in Ambient Air Using High  Performance Liquid Chromatography (HPLC) 
  • SOP MLD024 - Determination of Total Non-Methane Organic Compounds by  Preconcentration Direct Flame Ionization Detection (PDFID). 
  • SOP MLD032 - Determination of Non-Methane Organic Compounds in Ambient Air  Using Gas Chromatography with Flame Ionization Detection. 

Publications and Downloadable files

Contract Studies

Spatial and Temporal Characteristics of California PAMS and Long-Term Trend Site VOC Data (1990-1997), Sonoma Technology, Inc.,  Report prepared for Air Resources Board, Sacramento Metro Air Quality Management District, San Joaquin Valley Unified Air Pollution Control District, Ventura County Air Pollution District, and U.S. EPA, May 1999.  (Acrobat, 2,662KB) 

Analysis of PAMS Data in California Volume I: The use of PAMS Radar Profiler and RASS Data to Understand the Meteorological Processes that Influence Air Quality in Selected Regions of California, Sonoma Technology, Inc.,  Report prepared for Air Resources Board, Sacramento Metro Air Quality Management District, San Joaquin Valley Unified Air Pollution Control District, Ventura County Air Pollution District, and U.S. EPA, May 1999. (Full Report, Acrobat, 12,994KB) or (Main Text, Acrobat, 3,326KB), (Appendix A, Acrobat, 607KB), (Appendix B, Acrobat, 8,882KB), (Appendix C, Acrobat, 188KB) 

Analysis of PAMS Data in California Volume II: The Use of PAMS Data to Evaluate Regional Emission Inventories in California, Sonoma Technology, Inc.,  Report prepared for Air Resources Board, Sacramento Metro Air Quality Management District, San Joaquin Valley Unified Air Pollution Control District, Ventura County Air Pollution District, and U.S. EPA, May 1999.  (Acrobat, 251KB) 

Analysis of PAMS Data in California Volume III: Trends Analysis of California PAMS and Long-Term Trend Air Quality Data (1987-1997), Sonoma Technology, Inc.,  Report prepared for Air Resources Board, Sacramento Metro Air Quality Management District, San Joaquin Valley Unified Air Pollution Control District, Ventura County Air Pollution District, and U.S. EPA, May 1999.  (Acrobat, 1,431KB) 

Papers

Evaluation of Ambient Non-Methane Hydrocarbon Measurements Taken During 
the Winter of 1991-92 in Sacramento, California, Donald Hammond and Jeffrey P. Cook.  Technical paper presented at the Air & Waste Management Association 86th Annual Meeting & Exhibition, Denver, Colorado, June 13-18, 1993.  (Acrobat, 421KB

Abstract
The 1991-92 Sacramento Area Winter Hydrocarbon Study was undertaken by the California Air Resources Board (CARB) to examine the nature and distribution of ambient non-methane hydrocarbon (NMHC) species with respect to their concentrations and profiles. The winter period was selected as a time when hydrocarbon emissions would be least affected by photochemistry and afternoon mixing, and stable conditions would permit an examination of the impact of local emissions sources on air monitoring stations. The Study included measurements of speciated and total hydrocarbon measurements from four fixed monitoring sites and six mobile sites during the morning and afternoon. The evaluation of these results is intended to help develop a better understanding of the local and regional distribution of hydrocarbons in the Sacramento area, with a particular emphasis on specific hydrocarbon patterns in urbanized areas. In addition to examining spatial distribution, the paper contains an evaluation of a temporal (morning vs. afternoon) NMHC species, and a brief comparison to similar data collected during the ozone season. 

Ultimately, the spatial and temporal information from the Sacramento Winter Study and other monitoring programs will benefit ozone assessment activities and regulatory efforts. The United States Environmental Protection Agency (US-EPA) will be requiring extensive routine collection of VOC samples as part of the Photochemical Assessment Monitoring Station (PAMS) network in California. CARB and other state and local air pollution control agencies are exploring alternative collection schedules that will meet the PAMS data uses. The results of this and other intensive studies are an appropriate basis from which to develop the first years of the required network plans, particularly to meet those aspects that require a general characterization of precursor behavior. 

A Comparison Study to Determine the Effects of Pressure, Relative Humidity, and Canister Residence Time on NMHC Recovery Rates from Stainless Steel Canisters, Michael G. Miguel. Technical paper presented at the U.S. EPA/AWMA International Symposium on Measurement of Toxic and Related Air Pollutants, Research Triangle Park, North Carolina, May 16-18, 1995. 

Abstract
The Air Resources Board (ARB) conducted a canister comparison study to determine the effects of pressure, relative humidity, and canister residence time on non-methane hydrocarbon (NMHC) recovery rates from stainless steel canisters. The results of the study were used to support the photochemical assessment monitoring stations (PAMS) NMHC program and California's ambient toxics air monitoring program. The study was part of ARB's data accuracy evaluation to determine the best sampling conditions for compound recovery. As a result of the study, a protocol was established for the introduction of calibration, audit, and cleanliness samples to the analytical instrumentation. Compound recovery rates were not affected as a result of pressure, except when no humidity was present in the canister. The aromatic compound recovery rates increased as the canister pressure increased. Humidifying the canisters also improved the aromatic compound recovery rates, however, variations in the relative humidity above 18% showed no differences.  Additionally, the canister residence time had no effect on the compound recovery rates. As a result of the study, ARB confirmed that the humidified canisters improved the recovery rates of aromatic compounds when analyzing calibration, audit, or cleanliness samples. 

Voyager Data Files

  • Statewide Particulate and PAMS HC DataPKWare zipped file containing preliminary data for air pollutants and pollutant precursors sampled at seven California sites from June 1, 1993 to October 30, 1993. The Voyager file was used as a quality assurance tool to review the hydrocarbon data for year zero of the U.S. EPA mandated Photochemical Assessment Monitoring Stations (PAMS) program. The data taken during the Summer of 1993 will be used to assess the California Air Resources Board's monitoring capability and preview the ambient hydrocarbon patterns. (sum93.zip, 185K) 
  • Sacramento NMHC and Criteria Pollutant Data - PKWare zipped file containing criteria and NMHC pollutant data. The data were collected at four fixed sites from December 1991 through February 1992 and at six mobile sites in two week segments. The intent of the winter study was to examine the nature of sources, reactivity, and diurnal patterns of ambient hydrocarbon levels. (wntr_hc.zip, 74K) 


Related Links

The Enhanced Ozone Monitoring (PAMS) is an U.S. EPA site that provides the latest information concerning the PAMS program including data analysis support, nationwide networks and sites, publications and contacts. 

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