Ethylene Oxide Measurement Research

Update

State/USEPA Region 5 Air Toxics Risk Assessment

Meeting

November 12, 2019

Ned Shappley

Office of Air Quality Planning

and StandardsAir Quality Assessment Division

1

Center of Environmental Measurement and

Modeling

Tiffany Yelverton

Office of Research and

Development

2

AmbientNear-SourceSource

Measurement

Ethylene Oxide Basics

and Background

Agenda

Ethylene Oxide

3

• Chemical/Physical Properties

• Molecular weight: 44.053 g-mol

• Boiling point: 10.4C (51F)

• Water soluble

• Vapor pressure : 1.46 atm @ 20C

• Flash point : 20C (−4F)

• Half-life in atmosphere (38 to 382 days)

• Hazards

• Extremely flammable

• Irritant

• Mutagen

• Listed as a carcinogen

Production and

Usage (Industry

Slide)

4

5

Sensitivity Fit-for purpose

Ease of use Economically viable

Ideal Measurement Approach

EtO Measurement Challenges • Legacy methods are no longer sensitive enough to measure at the

concentrations needed to demonstrate compliance with some emission

standards .

• Ambient concentration for air toxics in the low ppt range has not been well

studied.

• Use of measurements to assist in

meaningful emission reductions.

• Measurement Push:

• Improve sensitivity

• Identify emission sources

• Quantification from non-traditional

emission points

• Real-time measurements

• Cost-effectiveness

Ethylene Oxide Regulations – Air Emissions

6

• Ethylene Oxide 1 of 187 regulated air toxics (Major and Area Sources)

• Active Rulemaking : Commercial sterilizers (O) and Miscellaneous Organic Chemical Manufacturing (FFFF)

• Other rules: Hazardous Organic NESHAP (F-H), Polyether Polyols Production (PPP), Hospital Sterilizers (WWWWWW), and more..

• Current Federal Emission Standards: Removal efficiencies (NA - 99%) or concentration value (1 – 20 ppmv)

• Future Federal Emission Standards: Removal efficiencies (99% - 99.99%) or concentration value (< 1 ppmv?)

National Emission Standards for Hazardous Air Pollutants (Major and Area Sources)

• Removal Efficiencies as low as >99.9 and concentration values of as low as < 0.2 ppmv

• Installation of Continuous Emission Measurement Systems (CEMS)

• Design Criteria (e.g., Method 204) and continuous monitoring for verification

State Air Toxic Rules

Ongoing Foundational Work

7

• No NIST Standard Reference Material (SRM) available

• Stability of and accuracy evaluation, of manufacturer “certified” standards

• Three months into a twelve months evaluation

• 5 vendors

• 4 ranges (100 ppbv to 100 ppmv)

• Alternative to NIST SRMs, EPA ALT-114 and ALT-118

Evaluation of commercially available calibration gas cylinder standards

• Analytical sensitivity vs. sample transport/sample recovery

• Sample material

• Sample temperature

Sample transport

Source Emission Measurements

8

• Appropriate techniques for existing emission standards

• Sensitivity concerns (all)

• Interference concerns (all)

• Method DQOs are not appropriate for low concentration measurements

Existing - Method 18 (GC-detector), Method 320 (FTIR),

and Method 25A (THC surrogate measurements)

• Near and Mid-IR optical spectroscopy approaches

• Better specificity

• Better sensitivity

• Good time resolution

RESEARCH:

New real-time techniques being evaluated

• Derivatization techniques

• Collection and concentration in an impinger train (Standard Method 5)

• Standard GC/ECD analytical finish

• Improved sample collection (isokinetic sampling) and theoretical sensitivity

RESEARCH:

Repurposed techniques (wet-impinger approach)

Wet impinger method

9

1.0 N HCl in

n-propanol

C2H5BrO + CH3CH(OH)CH3

HBr · CH3CH(OH)CH3C2H4O +

This Photo by Unknown Author is licensed under CC BY-SA

Mid and Near IR

Spectroscopy

Applications of Absorption Spectroscopy Using Quantum Cascade Lasers - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/HITRAN-simulation-of-absorption-

spectra-for-major-atmospheric-species-Color-figure_fig1_265856964 [accessed 3 Nov, 2019]

Optical techniques being developed and evaluated

11

BAND–PASS FILTER FTIR

- Commercially Available

- CEMS Application

- Method 320 compliant ???

- Source and near source application

- Detection limit 5 – 20 ppb @ 15 seconds

CAVITY RINGDOWN

- Mature technology

- Not commercially available (6- 12 months)

- Source and near source application

- Theoretical Detection Limit < 1 ppb @ 1 second

QUANTUM CASCADE LASER

- Specificity

- Not a commercial instrument

- Near source and ambient application

- Theoretical detection limit 100 ppt @ 60 seconds to 300 ppt @ 1 second

INTERBAND CASCADE LASER

- Commercially available

- Lower cost

- Near source applications

- Detection Limit < 1 ppb @ 30 second

MORE

Stationary Source Emission Measurements Products

12

New Performance Specification for oHAPs (CEMS)

- Performance Based approach for CEMS

- Possible Proposal Spring/Summer 2020 with commercial sterilizer rule

Other Test Method – Wet Impinger Approach (Possible)

- Draft Other Test Method, Summer 2020

- Method 301 validation field evaluation, Fall 2020/Spring 2021

- Possible Proposal Summer/Fall 2021 as Reference Method

New Optical Source Reference Method

- Performance Based Approach

- Self-validating method

- Possible Proposal Winter 2020/Spring 2021

Near-Source Measurements

13

Regulated fugitive emissions

• Leaks from valves, pumps, seals, and connectors

• Subject to LDAR program

• EPA Method 21 (FID or PID*)

• Threshold for leak repair @ 500 ppm to 10,000 ppm

• Limitations

• Instrumentation is not specific to EtO

• Periodic in nature

• Difficult to correlate a concentration to a mass emission.

Unregulated fugitive emissions

• Uncontrolled emissions leaving a building

• Atmospheric coolers, cooling towers, and holding tanks

• How do you measure/monitor?

Advanced and Emerging

Screening Techniques

• Area Leak Monitoring

– Utilization of existing monitors or emerging sensor technology

– Continuous monitoring for leaks

– Quick identification and repairs of leakage components

• Geospatial mapping of air pollutants (GMAP) vehicles

– Other Test Method - 33A

– Precise global positioning system and compact weather stations

– Fast-response Instruments

– Applications: fenceline and hot spot

14

Active Sorbent Trap Options (Fenceline)

15

• Refine procedures to improve sensitivity

• Longer deployment (a la Method 325A)

Build off the NIOSH/OSHA EtO sorbent trap methods

• EtO adsorbed on brominated carbon trap (ANASORB 747)

• Derivatizes it to stable 2-bromoethanol

Derivatization methodology

• Active sampling

• Trap design to allow for larger sample volume

• Alternative analytical technique to improve sensitivity

Evaluate

Near – Source Emission Measurements Products

16

Area Monitoring

- Bench evaluation of instrumentation Spring/Summer 2020

- Look for industry partner to evaluate for alternative fugitive monitoring approach Fall/Winter 2020

Mobile Platform Measurements

- Bench evaluation of instrumentation Spring/Summer 2020

- Possible field trials Fall 2020

- Draft procedures and guidelines (Winter 2020/Spring 2021)

Passive/Active Sorbent Approach

- Draft Other Test Method Winter 2020

- Method 301 validation field evaluation, Spring 2021/Summer 2021

- Proposal Winter 2021

Ambient Measurements

17

Improvement of Existing Methodology

• Leaks from valves, pumps, seals, and connectors

• Subject to LDAR program

• EPA Method 21 (FID or PID*)

• Threshold for leak repair @ 500 ppm to 10,000 ppm

• Limitations

• Instrumentation is not specific to EtO

• Periodic in nature

• Difficult to correlate a concentration to a mass emission.

Emerging and Innovative Techniques

• RARE Grant

• Additional Evaluation of Optical Techniques

• How low can we go?

Ambient Measurement

EPA Compendium Method TO-15 for Air Toxics

• Specially lined evacuated stainless-steel canisters (i.e., SUMMA or silica coated)

• Pre-concentration on a sorbent which is thermally desorbed and seperated and analyzed via GC/MS

• Proven detection limit* (SIM mode) of ~0.08 ug/m3 (~50 ppt)

• Limitations

– Interference with coeluting compounds

– Leadtime between sampling and analysis

– Sensitivity and Cost Concerns18

19

EtO GC/MS Basics

TO-15 Improvements for EtO

20

EtO measurements can be achieved by typical TO-15 set-up, with

limitation

• MDL not as low as desired even with selective ion monitoring

• Retention time shifts and tailing on typical non-polar columns

• Lower MDL and consistent retention time could be achieved by a polar column but effects performance for a few low MW air toxic analytes

Issues with abundant ions for quant.

• Ion 29 co-elutions (e.g., trans-2-butane)

• Monitor addition ions to aid EtO identification (41 and 56)

• Use of Ion 44 – CO2 and water management

• Leak Checks

• Optimization

• Data Review and validation

Innovative Ambient Approach

21

• EPA Office of Research and Development

• EPA Office of Air Quality Planning and Standards

• EPA Regions 5 and 6

US EPA Regional Applied Research Effort (RARE) grant

• Advanced sorbent sampling approach paired with optimized optical measurement approach(es)

• Goal : Single ppt detection limit

• Semi-continuous application

• Application to other air toxics

2 year grant to develop and deploy novel ambient/near-source measurement technology

Ongoing Measurement Efforts

22

23

Ethylene Oxide Concentrations

October 1, 2018 – March 31, 2019

Investigating the Distribution of EtO data Across the U.S.

24

• EPA has worked with the national air toxics

contract lab to analyze EtO concentrations

at a subset of the NATTS and UATMP sites

for the 4thQ 2018 – 1st Q 2019 period

• Outreach calls have been completed with

the affected states, and the data are in final

QA review prior to rollout/AQS posting

• The average concentration for this data set

is 0.297 μg/m3

• There is a statistical difference (lower)

between a grouping of [GLKY, LAWA,

SEWA] and the other sites

For Internal EPA Use

Only

Questions ?

25