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Posts Tagged ‘VOCs’

Vapor Intrusion Investigations: Air Sampling Tips for Meeting Data Quality Objectives

Monday, September 26th, 2011

N. Dagnillo1, L. Hill2, A. Fortune3, A. Smith4, and S. Thompson2
1Trihydro Corporation, 3001 E. Pershing Blvd, Suite 115, Cheyenne, WY 82007
2Trihydro Corporation, 1537 Riverside Ave., Suite 101, Fort Collins, CO 80524
3Columbia Analytical Services, Inc., 2655 Park Center Drive, Suite A, Simi Valley, CA 93065
4Trihydro Corporation, 9460 Calle Milano, Atascadero, CA 93422

Vapor intrusion is a fate and transport process characterized by the upward movement of volatile chemicals from subsurface contamination (e.g., buried waste, contaminated groundwater) into overlying buildings. The potential for adverse human health effects from exposure to indoor air vapors has motivated private, state, and federal entities to develop guidance documents and protocols specific to the collection and analysis of soil vapor data.

Read more about Vapor Intrusion Investigations…

Odor Investigations

Tuesday, June 3rd, 2008

Odor InvestigationsNuisance odors are a complex and subjective issue, often resulting in odor complaints directed at industrial or agricultural facilities such as wastewater treatment plants, landfills, large scale composting facilities, or animal feed operations. At these types of facilities, most odorous chemical compounds are produced under anaerobic conditions. Contrary to popular belief, nuisance odors themselves do not generally cause long term illness or any direct health effect.  In other words, if the source of the odor is taken away, any associated illness symptoms (e.g. nausea) will also go away. Therefore, unlike investigations centered on human health risk, investigations involving nuisance odor are governed by the perception of the receptor. A person’s perception of odor is related to the human olfactory system, which can vary widely from person to person; what smells bad to one person might not have an odor at all to someone else. To further confuse the issue, there is a distinct lack of odor regulations, and those that exist are extremely vague. The EPA defaults to the state level for nuisance odors, and most states defer to the county or local level.

Odor is a parameter which may be measured unto itself, following established ASTM and/or European Standards. This approach will quantify how odorous a sample is, ranking it on a relative scale with units of dilution to threshold (D/T).


Diffusive Sampling for Ambient Air and Other Low Level Applications

Saturday, July 26th, 2003

Diffusive Sampling for Ambient Air and Other Low Level ApplicationsDiffusive sampling has been a popular approach for the evaluation of workplace exposures to airborne contaminants, such as volatile organic compounds (VOCs) for some time. Typically, these “badge-type” samplers (e.g., 3M, SKC) have been used to evaluate exposures in the high part per billion (ppb) to part per million (ppm) range over an 8-hour period. A popular option, these samplers are easy to use, small in size and don’t require a sampling pump.

This approach involves the passive collection of an analyte on a solid sorbent via adsorption or chemical reaction. The sampling rate (e.g., diffusive uptake rate) is a function of the diffusive coefficient, which is compound and sorbent specific, and the geometry of the sampler used. Other factors that affect performance include temperature, pressure, humidity, air velocity and transient changes in contaminant concentrations. Samples are chemically desorbed and analyzed by gas chromatography with flame ionization detection (GC/FID) or by other appropriate instrumentation.