General considerations for sampling airborne contaminants

Details

• Personal Author:
  Ashley, Kevin E. ; McCammon, Charles S. ; Woebkenberg, Mary L.
• Description:
  In choosing methods for sampling of chemical and biological agents related to occupational exposures, thorough advance planning is required. Proper planning minimizes sampling and measurement costs while enabling the collection of high-quality data. Many criteria must be considered before collecting field samples from workplaces [ASTM International 2014]. The first step is to define the sampling objectives. These may include: a) documenting exposures in particular work settings; b) assessing compliance/non-compliance with existing regulatory or recommended occupational exposure limits (OELs); and/or c) determining sources of airborne contaminants. Sampling parameters that should be considered might include: a) type of sample (area vs. personal); b) contaminant(s) to be sampled; c) physical nature of airborne sample (vapor and/or aerosol); d) duration of sample collection; e) potential interferences; and f) estimated contaminant concentrations. Once these parameters are established, the suitable analytical method(s) and sampling media can be selected. For instance, when sampling for aerosols, the relevant particle size fraction to be sampled must be taken into account. Other general information needed to properly plan a sampling campaign include: a) the number of employees; b) the sampling strategy plan (discussed later); c) process flow diagram; d) safety data sheets on all process materials; and e) potential hazards involved in collecting and shipping field samples. An accredited analytical laboratory should be used to conduct analysis of collected samples, and it is essential to consult with the analytical laboratory before sampling to ensure that the measurement methods available can meet the defined measurement needs. Consultation with the laboratory should be an early part of survey planning. The laboratory can also assist in choosing sampling media that are compatible with the sampling needs and the measurement methods available. The APPLICABILITY sections of the individual methods in NMAM can be helpful in choosing which of the available methods is best for a particular situation. Apart from NIOSH methods, methods from other organizations such as OSHA, ASTM International and ISO may be appropriate [Ashley 2015]. The physical state(s) of the contaminant(s) being sampled may also be a factor in determining the media required. In the case of polyaromatic hydrocarbons (PAHs), for example, the correct sampler consists of a membrane filter to collect particulate matter and a solid sorbent tube to trap the vapors of certain PAHs so that total collection is assured. Also, for sampling of gases and vapors, it is generally necessary to mount a prefilter in front of the gas/vapor collection media in order to trap aerosols that might otherwise interfere with subsequent analysis of target analytes. The sampling pump used to collect the sample must also be compatible with the sampling needs and the media used. Specifically, the pump must be capable of maintaining the desired flow rate over the time period needed using the sampling media specified. Some pumps may not be able to handle the large pressure drop of the media. This may be the case for fine mesh solid sorbent tubes, small pore size filters or when attempting to take a short-term sample on a sorbent tube of a higher than normal pressure drop at higher flow rates. As a rule of thumb, higher-flow pumps (>1 L/min) can handle at least 3 kPa pressure drop at 1 L/min for 8 h. Some pumps can handle up to 7.5 kPa pressure drop at flows up to 5 L/min. Most low flow pumps (0.01 to 0.2 L/min) can handle the pressure drops of available sorbent tubes without problems, except that the nominal flow rate may decrease for certain models. All pumps should be calibrated with representative sampling media prior to use. It is good practice to check the pump calibration before and after use each day. As a minimum, calibration should be done before and after each use. [Description provided by NIOSH]
• Subjects:
  Aerosols Air Pollutants, Occupational Laboratories Occupational Health Particulate Matter Safety Solvents
• Keywords:
  Aerosol Particles Aerosol Sampling Airborne Particulates Gases PAC Particulates Physical Properties Polyaromatic Compounds Pumps Sampling Sampling Equipment Vapors

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• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Genre:
  Book
• Place as Subject:
  Ohio ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DART - Division of Applied Research and Technology
• Topic:
  Workplace Safety & Health
• Location:
  North America
• NIOSHTIC Number:
  nn:20048067
• Citation:
  NIOSH manual of analytical methods, fifth edition. Ashley K, O'Connor PF, eds. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2014-151, 2016 Apr; :SA1-SA-23
• Editor(s):
  Ashley K; O'Connor PF
• Federal Fiscal Year:
  2016
• Peer Reviewed:
  False
• Source Full Name:
  NIOSH manual of analytical methods, fifth edition
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:bdfa19bb0cefd258f209e1fa0ad1c23be7ed8ae7ab6febe04276264f18ea23cf743f332be0755ee011977b2b2be6f9acee29597a561297714eecadc090e821f1
• Download URL:
  https://stacks.cdc.gov/view/cdc/202935/cdc_202935_DS1.pdf
• File Type:
  [PDF - 478.26 KB ]