Air toxics sampling

Each of these examples suggest that air toxics sampling is complex and expensive and requires careful attention to quality assurance. 

EPA. 1986d. Emissions test report air toxics sampling at Wyckoff, Inc., Bainbridge Island,... 

Figure 4. Speciated Hydrocarbon Composition of Air Toxics Samples from the Fuel Processor or Tail Gas Combustor at Various Fuel Processor Loads...

Keith LH and Walker MM (1995) Handbook of Air Toxics Sampling Analysis and Properties. Boca Raton, FL CRC Press. 

Public awareness of the release of chemicals into the atmosphere has gone beyond the primary ambient pollutants (e.g., SO2 or O3) and governments require air toxics management plans. One component of this process is the characterization of the air quality via sampling. 

SRM 1649 was originally collected in a bag house over a period of one year in the late 1970s at a site near Washington, DC, screened through a 200-mesh sieve (cutoff point 125 gm), and since then apparently stored in bottles at room temperature (Lewtas et al., 1990a). Understandably, Claxton et al. (1992a) caution While the air particles in SRM 1649 are similar to other air particulate samples, they do not represent a typical air particulate sample as collected by most researchers—they are intended as reference materials and not as samples for assessment of levels of airborne toxicants. ... 

Conservative, non-labile parameters such as toxic metals, chloride, water soluble boron, elemental sulfur are analysed on the air-dried sample (30 5°C) after crushing and grinding, whilst labile and more volatile substances are analysed on the as received sample and the results converted to an air-dried basis after air drying a representative separate aliquot of the sample. The sampling for these labile and more volatile substances in the as received sample is more prone to error (i.e. lower precision) than sampling an air-dried, crushed and ground sample but ensures that the analyses are fit for purpose with respect to bias. 

On the last day of testing, grab samples were collected in Summa canisters and delivered to a loeal analytical laboratory (Air Toxics, Ltd., Folsom, CA) for TO-14 analysis to confirm the analyses provided by the MTI gas chromatographs and to provide outlet TCE concentrations that were below our GCs detection limits. Replicate samples were reported as 13000 ppbv for TCE in inlet air, and 280 and 660 ppbvTCEinthe outlet (Table 22.4.1). This corresponds to 97.8% and 94.9% removal of TCE. 

The wastes produced through the FPD processes, which include water generated by burning hydrogen in air and decomposed substances from the sample, are removed from the detector via a chimney exhaust. The toxic sample drawn into the detector is decomposed, and therefore detoxified, when it is burned in the hydrogen flame. 

We thank Joe Steinbacher and Bernie Crimmins and others at CBL for help with sample collection, and for help in bottle preparation and other laboratory activities. This study was funded by the EPA STAR Air Toxics Program, Grant R825245-01. This is Contribution No. 3462, Chesapeake Biological Laboratory, Center for Environmental Science, University of Maryland. 

Environmental Aspects. Airborne particulate matter (187) and aerosol (188) samples from around the world have been found to contain a variety of organic monocarboxyhc and dicarboxyhc acids, including adipic acid. Traces of the acid found ia southern California air were related both to automobile exhaust emission (189) and, iadirecfly, to cyclohexene as a secondary aerosol precursor (via ozonolysis) (190). Dibasic acids (eg, succinic acid) have been found even ia such unlikely sources as the Murchison meteorite (191). PubHc health standards for adipic acid contamination of reservoir waters were evaluated with respect to toxicity, odor, taste, transparency, foam, and other criteria (192). BiodegradabiUty of adipic acid solutions was also evaluated with respect to BOD/theoretical oxygen demand ratio, rate, lag time, and other factors (193). 

Eor toxic materials, it usually is advisable to provide ventilated sampling hoods or breathing-air stations and masks, to assure that the sampler is adequately protected from toxic or flammable vapors and dusts. Special provision for access to and exit from sampling points also may be needed at elevated locations and to avoid tripping or bumping ha2ards and to ensure that the sampler does not transverse areas not intended as walkways, eg, tank covers or roofs. 

Polymers. Studies to determine possible exposure of workers to residual epichl orohydrin and ethylene oxide monomers in the polymers have been done. Tests of warehouse air where Hydrin H and Hydrin C are stored showed epichl orohydrin levels below 0.5 ppm. Air samples taken above laboratory mixing equipment (Banbury mixer and 6" x 12" mill) when compounds of Hydrin H or C were mixed gave epichl orohydrin levels below detectable limits, and ethylene oxide levels less than 0.2 ppm, well below permissible exposure limits (46). A subacute vapor inhalation toxicity study in which animals were exposed to emission products from compounded Parel 58 suggests that no significant health effects would be expected in workers periodically exposed to these vapors (47). 

For many applications it is found that the technique of free sintering is quite satisfactory. This simply involves heating the preform in an oven at about 380°C for a time of 90 minutes plus a further 60 minutes for every 0.25 in (0.65 cm) thickness. For example a sample 0.5 in (1.25 cm) thick will require sintering for 3.5 hours. The ovens should be ventilated to the open air to prevent toxic decomposition products accumulating in the working area. 

The LC50 is the lethal concentration of chemical (e.g. in air or water) that will cause the death of 50% of the sample population. This is most appropriate as an indicator of the acute toxicity of chemicals in air breathed (or in water, for aquatic organisms). Table 5.11 illustrates the use of LD50 values to rank the toxicity of substances. 

Provision for monitoring and sampling, e.g. of oxygen levels, combustible gases and airborne toxic substances and the taking of samples from air, water and ground. 

EPA. 1987d. Intercomparison of sampling techniques for toxic organic compounds in indoor air. Northrop Services, Inc., Research Triangle Park, NC U.S. Environmental Protection Agency. EPA/600/4-87/008. 

Table 3 provides general guidelines used in toxic air assessments in California for sampling common agricultural pesticides in ambient air at near-field sampling monitors before, during, and shortly after a field application. For communities that are near the site of the candidate pesticide application, concurrent ambient air samples are taken over durations of 24 h and are collected 4 days per week for a period of 4 weeks. 

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