Grantee Research Project Results
Final Report: High Fidelity, Library Based THz Air Toxic Monitoring System for Neighborhood-Level Surveillance
EPA Contract Number: 68HERC23C0017Title: High Fidelity, Library Based THz Air Toxic Monitoring System for Neighborhood-Level Surveillance
Investigators: Brothers, Michael
Small Business: UES Inc.
EPA Contact: Richards, April
Phase: I
Project Period: December 1, 2022 through May 31, 2023
Project Amount: $99,940
RFA: Small Business Innovation Research (SBIR) Phase I (2023) RFA Text | Recipients Lists
Research Category: SBIR - Homeland Security , SBIR - Sustainability , SBIR - Water , SBIR - Air and Climate
Description:
The EPA wants to monitor neighborhoods and communities for exposure to air toxics, as these compounds have an adverse impact not only on the environment, including ecosystems, but also on human health. The health impacts from air toxics vary depending on the air toxic, pathway of exposure, concentration, and duration. Chemical exposures can result in superficial and acute medical conditions (e.g., burns and blistering), as well as chronic conditions such as cancer. Despite many chemicals, including volatile organic compounds (VOCs), having minimal toxicity (i.e., no significant health impacts for exposures < 100 parts per million (ppm)) according to the National Institute of Occupational Safety and Health (NIOSH), others are known to impact health even at low concentrations (> 5 ppm). Therefore, it is imperative to not only quantitate air toxics, but to also identify them.
Despite the need for transportable analytical instrumentation to monitor and assess air toxics in communities, the current available instrumentation is limited. Currently fielded transportable instrumentation consists of 1) hand-held monitors with limited ability to ascertain the toxicity of a chemical exposure, 2) methods that can identify compounds in the absence of interfering agents (e.g., ion mobility spectrometers (IMS), Fourier-transform infrared (FTIR) spectroscopy, gas chromatography (GC)), but can be confounded by background compounds, and/or 3) expensive analytical instruments (such as transportable mass spectrometers (MS)). The currently available analytical instrumentation requires end users to make an unpalatable tradeoff between data accuracy, cost, and convenience. Therefore, new analytical instrumentation is required that can 1) identify target air toxics, 2) be insensitive to interfering agents, and 3) remain affordable to municipalities and regulatory agencies.
Terahertz (THz) spectroscopy is a promising, emerging solution to this critical gap, as it can uniquely detect and identify a wide range of compounds based on key, unique vibrational or rotational modalities leveraging spectral libraries. Recently, a collaborative team including UES and Wright State University (WSU) demonstrated gaseous phase identification and detection of analytes at the parts per billion (ppb) level in breath using THz spectroscopy.
Therefore, UES in conjunction with its partner WSU in this phase designed the first transportable THz air toxic monitor. This device would provide the EPA a reliable, transportable capability to identify and quantitate air toxics in order to perform autonomous assessment of air quality. The proposed miniaturized instrumentation would bring unique analytical capabilities to the field for both stationary and mobile environmental surveillance efforts. Successful delivery of the proposed product will also support larger EPA goals. Notably, the EPA has expressed sustainability as a priority interest of the EPA. This transportable air toxic monitor would support sustainability efforts by enabling monitoring of toxic emissions, and thus providing data critical towards reducing the environmental footprint of the United States.
Summary/Accomplishments (Outputs/Outcomes):
The research conducted during Phase I used an existing THz spectroscopy unit to build a library of THz spectral fingerprints for select air toxics and identified key spectral features that enable identification and quantitation of these select air toxics. The following key findings were made.
THz spectroscopy is capable of selective and sensitive identification and quantitation of air toxics. Most notably, of the 30 air toxics listed by the EPA, 15 were detectable via THz spectroscopy. Resolved spectral snippets were identified for each of the target 15 air toxics and five additional industrial gases. Preliminary fitting algorithms were developed to enable automated quantitation of select air toxics. Even more impressively, 14 of the 15 air toxics are predicted to be detectable, identifiable, and quantifiable at concentrations lower than 10% of the permissible exposure limit (ppb levels); the other compound is calculated to be detectable at the low ppm concentration. Five other compounds, including NO2, SO2, and common hydrofluoroalkanes used in refrigeration could also be detected and quantified at the ppb levels.
For the proposed integrated device, a protocol was designed and optimized that can collect ambient air, process the air, acquire the THz spectra, and analyze the data in under ten minutes. This means that atmospheric gas analysis could be performed in pseudo real-time.
Significant engineering work was performed to design a ruggedized version of the THz spectrometer that is proposed to be built during Phase II. Notably, commercial electronics and OEM parts were identified that could improve the transportability of the unit, the ruggedness of the unit, and the mass-manufacturability of the unit. The final unit as designed will fit within a 25"x25"x20" case that contains anti-shock technologies to prevent damage to the encased electronics and enable both transportation, as well as deployment in more austere conditions.
While the current technologies support a high-resolution, higher cost gas phase analyzer, emerging technologies in adjacent fields provide the promise and hope that key components can result in a price-point that can enable more wide-spread adaptation of THz spectroscopy for neighborhood air monitoring and surveillance.
Conclusions:
Dr. Brothers presented at both Pittcon and at the Ohio Safety Congress to scout emerging technologies as well as identify customer pain-points. Notably, the talk at the Ohio Safety Congress (OSC) was a course credit to those in the safety profession, including those in charge of chemical hygiene. The talk delivered was entitled “Emerging Technologies for Atmospheric and Chemical Monitoring”. Much of the presentation was focused on the recent vinyl chloride spill in Palestine Ohio (https://www.cnn.com/2023/02/23/us/ohio-train-derailment-east-palestine-thursday/index.html) and other hot topics to highlight the importance of monitoring air toxics.
When fielding questions at the OSC, it was clear that end users that are responsible for the industrial and chemical hygiene at plants needed solutions that could reliability detect and quantify formaldehyde, ethylene oxide, acrylonitrile, and many other compounds highly suitable for THz spectroscopy. The demand from end users was clear. Additionally, the need for simplicity in operation was also conveyed by end users.
During these conferences, Dr. Brothers met and consulted with the companies there and confirmed that no technologies currently met the market need for a high ppb/low ppm level unit that can identify and quantify air toxics. Thus, this THz-based atmospheric monitoring unit would address a missing component needed for environmental and occupational monitoring of chemical hazards and air toxics.
Additionally, our team engaged in market research with Foresight and Dr. Robert Feeney. This market research confirmed that our proposed THz air toxic monitor has not only commercial viability, but could serve as a disruptive technology in the air monitoring space to enable rapid, accurate identification and quantitation of key air toxics.
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.