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Evaluation of Continuous Formaldehyde Measurements
Citation:
Whitehill, A., R. Long, AND S. Kaushik. Evaluation of Continuous Formaldehyde Measurements. National Ambient Air Monitoring Conference 2018, Portland, OR, August 13 - 16, 2018.
Impact/Purpose:
Formaldehyde is an important hazardous air pollutant (HAP) that is a leading driver for HAP-related cancer risk in the United States. It is also a significant source of radicals in the atmosphere that result in ozone and particulate matter (PM) formation. Routine measurements of formaldehyde in regulatory networks rely EPA Compendium Method TO-11a, which is based on HPLC analysis of derivatized, time-averaged cartridge samples. This work describes the ongoing evaluation and comparison of next-generation formaldehyde monitoring instrumentation. Most of this is based on spectroscopic principles and can measure formaldehyde continuously (in real time) at high precision. We present results from our ongoing evaluation and intercomparison of newer formaldehyde measurement technologies in both controlled laboratory experiments and ambient air. The long-term importance of this work is that it opens the door to various stakeholders to utilize new technologies to enhance ambient air monitoring networks. This work directly supports the PAMS program, which allows for continuous formaldehyde measurements, as well as regions and states interested in making real time formaldehyde measurements to address NAAQS non-attainment issues, community health and exposure issues, and near-source emissions measurements.
Description:
Formaldehyde and other carbonyl compounds are highly reactive, and multiple NAAQS exceedance studies have demonstrated them to be significant precursors of ozone and PM 2.5. In addition, formaldehyde is a key driver of hazardous air pollutant cancer risk nationwide. The EPA's Office of Research and Development, under CAA §103 (USC §7403), is involved in the ongoing development and validation of improved methods and technologies for the measurement of volatile organic compounds and ozone precursor species, including carbonyls such as formaldehyde. The current EPA method for carbonyl measurement, Compendium Method TO-11A, is currently being evaluated and updated, but has various known issues and is of limited usefulness for high time resolution data. Specific weaknesses of TO-11A include DNPH blanks, the potential for co-eluting compounds, interferences from ozone, nitrogen dioxide, and inconsistent collection efficiencies that are a function of collection time and relative humidity. ORD is actively engaged in the ongoing development, testing, and validation of real-time, continuous (spectroscopic) formaldehyde measurement techniques, as well as time averaged (with cartridge derivatization) gas chromatographic techniques for carbonyls. We will present preliminary results from an ongoing evaluation of commercially-available continuous formaldehyde monitors. Depending upon the goals of the specific network or study, these new techniques have the potential to provide improved temporal resolution, data quality, and consistency at a lower total operating cost.