Questions and Answers: About the Current Monitoring Data
- Has the EPA been monitoring air quality since Sterigenics opened in 1984? Is there a record of air quality reports from 1984 to current?
- Are the MACT standards for sterilization facilities being reviewed? Any updates in regards to the air toxics emissions standards for MON?
- Were samples being collected on December 23, 2019?
- Is there historical data somewhere that actually found trans-2-butene, or is that just an alternate hypothesis that is theoretical in nature?
- Did Sterigenics have input into the selection of the sampling company?
- What do the initial monitoring results say about risk in the communities near the Sterigenics Willowbrook facility?
- Monitors closest to the Sterigenics facility detected levels of ethylene oxide as high as 6.6 micrograms per cubic meter of air (ug/m3). Don’t such levels prove there is elevated risk here?
- Some monitors did not detect ethylene oxide. Does that mean there is no ethylene oxide in the air at those locations?
- How do these results compare to the results from the monitoring EPA Region 5 conducted in the Spring?
- Why can’t you tell me my risk from these monitoring results?
- U.S. EPA recently said that it had discovered that the chemical trans-2-butene could be incorrectly identified as ethylene oxide when air quality samples are being analyzed in a laboratory. Did EPA account for this when it analyzed the air quality samples recently collected in Willowbrook?
- U.S. EPA recently admitted it that may have mistakenly identified trans-2-butene as EtO. When and how was the existence of this interference with trans-2-butene discovered? Given your budget of billions how was this allowed to happen? What have you implemented to prevent it from happening again?
- You said you did not find any trans-2-butene in the samples collected on November 13, 16 and 18. Can we assume that there also was not any trans-2-butene in the air samples collected in mid-May in Willowbrook?
- Did the trans-2-butene interference issue affect the toxicity studies that the standards have been based on?
- What are the monitoring limitations, longterm public health risk and timing of results from test?
- What is the detection limit for the air testing around Sterigenics?
- I understand you started monitoring three weeks ago. Why haven’t you shared any data?
- Why did it take you so long to start monitoring?
- You only have 8 monitoring locations. How can that possibly be enough?
- Why are you only monitoring for 3 months?
- How does monitoring account for operations at the facility?
- Except for one, locations that have been chosen for ongoing monitoring don't seem to account for winds out of the north, NW or NE. I can assure you that in the winter months, northerly winds are very frequent.
- Where is EtO air monitoring in the nation that is not around an EtO polluter? When will these results be available?
About the Current Monitoring Data
Has the EPA been monitoring air quality since Sterigenics opened in 1984? Is there a record of air quality reports from 1984 to current?
EPA does not have historical air toxics monitoring data for the area near Sterigenics. Air toxics are generally a local issue and there are a number of reasons that EPA does not comprehensively monitor all air toxics concentrations or emissions at all locations. Instead, EPA relies on the National Emissions Inventory (NEI) that uses emissions data reported by facilities and collected by State, Local, and Tribal air agencies.
Beginning in 2003, EPA established the National Air Toxics Trends Station (NATTS) Network, that includes 20 urban and 7 rural monitoring sites throughout the United States. These sites are maintained and operated by the states. The nearest NATTS site to Willowbrook is located in Chicago. There are typically over 100 pollutants monitored at each site, although, only 19 pollutants are required; included are VOCs, carbonyls, PM10 metals, hexavalent chromium, and PAHs. Ethylene oxide measurements have not been collected in the past from these sites.
Are the MACT standards for sterilization facilities being reviewed? Any updates in regards to the air toxics emissions standards for MON?
EPA has existing rules for industries that emit ethylene oxide, and we have begun to review those. EPA is currently conducting a Risk and Technology Review (RTR) for the Miscellaneous Organic National Emissions Standards for Hazardous Air Pollutants (also known as the MON). The agency has a court-ordered deadline that requires the MON RTR be finalized by March 13, 2020. We expect a proposed rule in the summer of 2019. We are also beginning work to look at emissions standards for commercial sterilizers like Sterigenics.
Were samples being collected on 12/23?
No. December 22 and 26, 2018 were sampling days.
Is there historical data somewhere that actually found trans-2-butene, or is that just an alternate hypothesis that is theoretical in nature?
U.S. EPA's monitoring method for ethylene oxide has limitations, and Agency scientists have been working to improve that method. As part of that work, they discovered in Fall 2018 that another chemical – called trans-2-butene – may look like ethylene oxide when air samples are being analyzed in a lab. Once the issue was identified, EPA was able to have its contract laboratory analyze for trans-2-butene separately from ethylene oxide.
Did Sterigenics have input into the selection of the sampling company?
No. EPA's Region 5 technical staff are collecting the samples. EPA's national laboratory contractor is analyzing and quality assuring them. EPA is completing a final quality assurance review in house before making the data public.
What do the initial monitoring results say about risk in the communities near the Sterigenics Willowbrook facility?
It is premature to draw conclusions from the limited, short-term data. Long-term risk cannot be determined from short-term monitoring data alone. The Agency will conduct a full assessment of risk from ethylene oxide in the air in the Willowbrook area; we expect this assessment to be complete by spring 2019.
Monitors closest to the Sterigenics facility detected levels of ethylene oxide as high as 6.6 micrograms per cubic meter of air (ug/m3). Don’t such levels prove there is elevated risk here?
It is premature to draw conclusions from the data. While the two monitors closest to the Sterigenics facility detected ethylene oxide in the first three days of air quality sampling, the results from those monitors varied widely – from 0.8 to 6.6 ug/m3 at one monitor, for example.
Additional monitoring, as well as other information gathering, will be necessary before U.S. EPA can fully characterize ethylene oxide levels in the outdoor air in the communities surrounding the Sterigenics Willowbrook facility. EPA plans to continue monitoring in the Willowbrook area for three months and will continue to post data as it becomes available.
Some monitors did not detect ethylene oxide. Does that mean there is no ethylene oxide in the air at those locations?
Not necessarily. Existing monitoring methods are not sensitive enough to detect ethylene oxide at low levels in the outdoor air. U.S. EPA is working to develop new techniques for measuring ethylene oxide in the outdoor air to improve our ability to measure ethylene oxide at low levels.
How do these results compare to the results from the monitoring EPA Region 5 conducted in the Spring?
Results of the monitoring U.S. EPA is currently conducting in Willowbrook cannot be directly compared to the May 2018 monitoring. U.S. EPA is currently sampling air for 24-hour periods. The U.S. Region 5 monitoring included 12-hour samples, and “grab samples.” In a grab sample, a canister is opened, collects air for a very short period of time, and is then closed. Neither 12-hour samples nor grab samples can be compared to samples collected over 24 hours. In addition, the current samples are being analyzed using a method that is more refined for ethylene oxide.
Why can’t you tell me my risk from these monitoring results?
Outdoor air quality monitoring provides important information, but not enough to fully characterize risk. Existing monitoring methods are not sensitive enough to measure ethylene oxide concentrations at low levels that may still require action. As a result, to accurately assess risk from ethylene oxide in the Willowbrook area, EPA needs information about the total ethylene oxide emissions from the Sterigenics facility. This includes information about emissions from the stack as well as information about emissions that escape from the facility through vents and doors, etc, also known as “fugitive emissions.”
U.S. EPA has information on Sterigenics’ stack emissions and initial estimates of the facility’s fugitive emissions. The information we get from our air quality monitoring will help us understand if those estimates need to be adjusted.
Once we have better estimates of the fugitive emissions, we will be able to combine that with the stack emissions to model how much ethylene oxide is in the outdoor air. This approach will allow EPA to better understand Sterigenics’ ethylene oxide emissions relative to background levels. EPA will use the model results to determine the estimated risk in the community, and we expect the full risk assessment to be complete by spring 2019.
U.S. EPA recently said that it had discovered that the chemical trans-2-butene could be incorrectly identified as ethylene oxide when air quality samples are being analyzed in a laboratory. Did EPA account for this when it analyzed the air quality samples recently collected in Willowbrook?
Yes. U.S. EPA made a change to its method for analyzing air quality samples to prevent trans-2-butene from being misidentified as ethylene oxide. EPA’s contract laboratory did not find any trans-2-butene in the samples collected on November 13, 16 and 19. U.S. EPA will continue to analyze air quality samples collected in the Willowbrook area for both ethylene oxide and trans-2-butene.
U.S. EPA recently admitted that it may have mistakenly identified trans-2-butene as EtO. When and how was the existence of this interference with trans-2-butene discovered? Given your budget of billions how was this allowed to happen? What have you implemented to prevent it from happening again?
U.S. EPA's monitoring method for ethylene oxide has limitations, and Agency scientists have been working to improve that method. As part of that work, they discovered in Fall 2018 that another chemical – called trans-2-butene – may look like ethylene oxide when air samples are being analyzed in a lab. Once the issue was identified, EPA was able to have its contract laboratory analyze for trans-2-butene separately from ethylene oxide.
You said you did not find any trans-2-butene in the samples collected on November 13, 16 and 19. Can we assume that there also was not any trans-2-butene in the air samples collected in mid-May in Willowbrook?
We don’t know whether there was any trans-2-butene in the May 2018 air quality samples, because those samples no longer are available for analysis
Did the trans-2-butene interference issue affect the toxicity studies that the standards have been based on?
The trans-2-butene issue U.S. EPA identified relates to monitoring for ethylene oxide in the outdoor air. It is not related to toxicity studies used in the December 2016 update of EPA's health value for ethylene oxide. That health value is used to assess risk from a lifetime exposure (70 years) to ethylene oxide. It is not a standard for the amount of ethylene oxide allowed in the outdoor air.
What are the monitoring limitations, longterm public health risk and timing of results from test?
The principal limitation of the ambient sampling effort is the sensitivity of the laboratory analysis method being used to measure ethylene oxide in the canisters. The sensitivity of the current method, often referred to as the Method Detection Limit (MDL), is 0.082 micrograms per cubic meter (µg/m3). Our current monitoring technology cannot detect ethylene oxide below that level. Ambient sampling commenced at two of the sites on November 13 and at all of the sites on November 19. Data should become available approximately 21 days after sampling.
What is the detection limit for the air testing around Sterigenics?
Sample collection methods have a detection limit of approximately .08 micrograms per cubic meter (µg/m3).
EPA’s contract laboratory for the Ethylene Oxide study in Willowbrook can achieve a Method Detection Limit (MDL) of 0.082 µg/m3. General information about the sampling plan is available at this site: https://19january2021snapshot.epa.gov/il/outdoor-air-monitoring-willowbrook-community.
I understand you started monitoring three weeks ago. Why haven’t you shared any data?
The way pollutants like ethylene oxide are measured does not allow us to share data in real time. We use a type of canister to capture a sample of air. Once we get that sample – it takes 24 hours – the canisters are shipped to EPA’s contract laboratory for analysis. After the samples are analyzed and quality assured, we will share them with the public. All of this will take about 21 days for processing, analyzing, and quality assuring a day’s sample.
Why did it take you so long to start monitoring?
- Gather information to help identify monitor locations – in particular, facility emissions, weather data, and computer modeling (to determine appropriate downwind distances and directions)
- Provide an opportunity for local elected officials to identify other locations of interest
- Order and deploy sampling equipment
All this was necessary to make sure we are getting data to best characterize both the quality of the air that you are breathing and the impact of the facility on outdoor air levels.
You only have 8 monitoring locations. How can that possibly be enough?
U.S. EPA has a lot of experience conducting ambient air monitoring. EPA monitoring experts have determined that 8 monitors are sufficient to provide us the information we need. We will review the data as it comes in and determine if changes are needed to the monitoring plan. We also determined that 3 months is the minimum amount of monitoring needed to inform the planned risk assessment. To monitor beyond that timeframe would delay the risk assessment, which is something that we do not want to do. If anything changes with the monitoring plan, we will be in touch with local officials and the community.
Why are you only monitoring for 3 months?
We believe that three months is the minimum period of data needed to inform our risk assessment. The risk assessment will serve as the basis for determining what additional actions are needed. We don’t want to delay the risk assessment by waiting for months/years of more monitoring data.
How does monitoring account for operations at the facility?
Our monitoring locations were selected to provide information on air concentrations both close to the facility and in the surrounding neighborhoods. Science tells us that the highest pollution levels occur close to the pollution source. Two monitors are sited very close to the two Sterigenics buildings. By operating these two monitors – and the other six monitors in the surrounding neighborhoods – over the 3-month sampling period, we will be able to measure air concentrations affected by the operations of the facility.
Except for one, locations that have been chosen for ongoing monitoring don't seem to account for winds out of the north, NW or NE. I can assure you that in the winter months, northerly winds are very frequent.
As outlined in the monitoring plan, the winter wind rose shows the predominant winds from the west/southwest. This is based the most recent five years (2013-2017) data, using a combination of surface and upper air data. We considered this information, along with input from local elected officials, in identifying monitoring locations in surrounding neighborhoods.
Where is EtO air monitoring in the nation that is not around an EtO polluter? When will these results be available?
Nationally, there is very little recent air monitoring data for EtO. U.S. EPA is currently aware of air monitoring for EtO performed in Illinois and Colorado. EPA will work with other state air agencies that want to conduct such monitoring and will look for other opportunities to collect EtO monitoring data.