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Assuring that evolving air standards are met

By Stacy Gittleman


B­reathe in. Breathe out. The purity of the air we breathe is an ever-changing target, as toxins are emitted into the environment, corporations test chemicals, and the environment degrades. Those of us living in Michigan depend not only on federal standards to protect our air quality, but on evolving state standards of industry and nature, and for agencies to stay current on all of changes and to provide permits and to communicate them to the appropriate parties in a timely fashion.


Michigan’s Department of Environment, Great Lakes and Energy (EGLE) is gearing up for a productive 2023. After years of being criticized for underfunding the state agency charged with protecting the state’s air, water, land and other natural resources, the state legislature on July 1, 2022, approved a bipartisan budget for the fiscal year that began October 1, 2022, slating $729 million for EGLE. That's a 31 percent increase over last year’s budget, and the increased funding allows EGLE to hire 53 new full-time employees.


That’s good news for EGLE’s Air Quality Division (AQD), which has been allocated $4.4 million and the go-ahead to hire 15 employees within its ranks for air quality permitting. Among the many tasks and departments of AQD include emissions monitoring, modeling and reporting, enforcing compliance of state and federal air regulations as outlined within the Environmental Protection Agency’s (EPA) Clean Air Act, lies a tiny group of four toxicologists who make up the Toxics Unit.


The Toxics Unit, assigned the task of regulating sources of air pollutants to protect human health, is charged with creating and updating heath-based screening levels of hundreds of chemicals which are utilized by thousands of businesses in the state that operate within the AQD’s permits to install regulatory programs for the assessment of toxic air contaminant emissions. It is the Toxics Unit’s task to maintain, update and monitor an ever-growing database of what is known as the List of Screening Levels. Created in 1988, the List of Screening Levels now stands at 1,269 toxic air contaminants. The unit in 2021 added 26 new screening levels to the list as they relate to human health exposure risks.


The open-ended list is readily available on EGLE’s website. Chemicals under review for consideration of altering screening levels are also up for public comment. In the early years of the screening program, memos describing the justification for the screening levels were only available upon request. While the public always had the ability to informally comment on the screening levels, as of December 2016, to provide further transparency, the division formalized the comment process and provides a 30-day formal public comment period on all health-based screening levels and their justifications.


Toxicologists develop screening levels by reviewing existing toxicology literature and evaluating health-based limits published by other environmental agencies to create screening levels which are the most appropriate and defensible values. The division prefers large human studies of sensitive toxicology endpoints over animal tests.


The health risks of chemicals are measured in screening levels designed to provide a level of protection to the public from inhalation exposure and are measured in micrograms per cubic meter. An Initial Threshold Screening Level indicates no cancer effects, and Initial Risk Screening Levels means a one in million risk of a cancer effect. A Secondary Risk Screening Level indicates a one in a hundred thousand risk of a cancer effect.


As of October 2022, the Toxics Unit currently lists 21 chemicals which are under review for reevaluation of their screening levels. They range from chemicals in the alcohol family; chemicals used for mold control or insecticides; paint solvents; degreasers; pharmaceuticals; perfumes; fossil fuel additives; and a host of other industrial applications. This review is being undertaken to either develop a screening level where one does not currently exist, or to evaluate an existing screening level to determine if new scientific data is available that would indicate a revision is needed. The screening levels are used in the implementation of Michigan’s air toxic rules that apply to new or modified sources that emit a toxic air contaminant, and are required to obtain a permit to install. Under these rules, the emission of a toxic air contaminant cannot result in a maximum ambient concentration that exceeds the applicable health-based screening level.


“Michigan’s air toxics program is unique,” said Chris Ethridge, assistant division director of EGLE’s Air Quality Division. “Most state environmental departments do not have a specific dedicated air toxics program. The work of the AQD’s Toxics Unit goes above and beyond what the Clean Air Act requires. It gives Michigan the ability to be able to evaluate and regulate many toxic air pollutants that aren't necessarily covered under the Clean Air Act.”


Ethridge has worked within AQD for 23 years, starting out as a field inspector and then as a supervisor for field operations. Recently, he stepped into his new executive position where he is responsible for permit oversights and compliance, field operations and indirectly the Toxics Unit.


Regarding a boost to the 2023 budget, Ethridge said that the AQD will greatly benefit from the funding boost and will be able to hire 15 new employees, including four new permit engineers and one more toxicologist. This will help the agency better respond and process permit applications, a complaint heard from the state’s manufacturing sector, he added.


“We have heard loud and clear from industry that getting those permits to install issued promptly is critical. As part of the Clean Air Act, a manufacturer cannot start construction or add a piece of equipment until that air permit has been issued. So, it’s obviously critical to industry to have those permits in hand within a reasonable time. And with one more toxicologist on staff, we will have a broader bandwidth to perform toxics reviews.”


According to Ethridge, the Toxics Unit embarks on reviews of chemicals being used by industries in Michigan as it relates to the air permitting program. The screening levels are then used across the permitting system for permit holders for a variety applications. Under these rules, the emission of a toxic air contaminant cannot result in a maximum ambient concentration that exceeds the applicable health-based screening level.


A permit is required for projects that involve installing, constructing, reconstructing, relocating or modifying most processes or process equipment that emit, or may emit, air contaminants.


According to AQD’s 2021 annual report, in the last five years the division received an average 400 permits to install applications and approved on average 341of them.


“Sources requiring a permit to install will undergo a thorough review of their air emissions,” explained Jill Greenberg, EGLE public information officer. “If applicable, stack testing will be required as part of the permit conditions. Sources not needing a permit have been determined to have minimal emissions and impacts to the environment, so testing is typically not required in that case. Air quality division, however, always reserves the right to request a stack test from a facility – even in situations where it has not been specifically required as part of a permit.”


Greenberg said companies applying for a permit to install are responsible for identifying all emissions of air pollution from their equipment. EGLE is also aware of the different types of pollutants that are expected from different types of industries, and verifies that the information provided is accurate.


From a federal standpoint, Greenberg explained that EGLE works closely with the EPA on documenting and monitoring the main pollutants regulated, known as the six criteria pollutants – which are nitrogen oxides, sulfur oxides, carbon monoxide, particulate matter, photochemical oxidants (including ozone), and lead. EGLE compares its results to the National Ambient Air Quality Standards (NAAQS), which are the health-protective standards set by the US Environmental Protection Agency (USEPA). Comparisons of data to the NAAQS are often done over a three-year time span, depending on the pollutant. The purpose of ambient air monitoring is to provide air quality data for regions and areas where people live, work, and play.


While Ethridge explained many states mimic regulations of the 1990 Clean Air Act to monitor air pollutants, Michigan deemed that the EPA’s finite list of 187 Hazardous Air Pollutants is an insufficient list if human health is to be protected compared to Michigan’s more open-ended inventory of toxic air pollutants.


“Outside of the list of main pollutants listed in the federal Clean Air Act, there are many potentially toxic air pollutants that may pose a health threat to humans. But unless the EPA specifically passes a specific regulation on that chemical or process, a state may not have the ability to regulate it. Under Michigan’s permit to install program, we can evaluate and set limits for any aero toxin of concern that we encounter when we go through our permitting process. This gives us wider breadth and ability to be able to address and regulate toxic air pollutants,” Ethridge said.

Ethridge explained that facilities are required to apply for a permit for any new processes they are introducing to their facility. AQD’s permit engineers will evaluate the different chemicals of concern that may be potentially used and what air pollutants could be emitted.


"If the industry identifies the toxic chemicals that need to be evaluated, because of the significant level of how much toxins could be emitted from the process, we have one of two options," explained Ethridge. "We can either look at existing data that we have on that chemical and use the health screening levels that have already been developed. Or, if a permit applicant proposes that they wish to use a chemical that we have not examined before, and if no screening levels have been developed, we will share this chemical with our Toxics Unit. The Toxics Unit will then evaluate the chemical and create a set of screening levels for it. Those screening levels will then be utilized as criteria when the time comes for reissuing a permit as specific emission limits on that chemical will be set."


To develop screening levels for chemicals, Ethridge said air quality division toxicologists do not perform their own tests but delve into the body of already-published scientific and medical literature on the chemical.


“We're not testing the chemical as we are looking towards already existing data to determine whether screening levels need to be set or not,” Ethridge explained. “Testing happens within other facets of our program. If a facility is issued an air permit and has specific emission limits in that permit, it may be required to do chemical testing at its own cost to show compliance with those emission limits. Testing typically is something that occurs after a permit has been issued to the facility and it's done at the company's expense with our oversight to assure everything complies with their permit.”


The task of testing new and emerging chemicals before they emerge on the commercial market rests with the EPA. That role falls under the EPA’s Toxic Substances Control Act (TSCA) of 1976. Under the TSCA, the EPA's New Chemicals program helps manage the potential risk to human health and the environment from chemicals new to the marketplace. The program functions as a "gatekeeper" that can identify conditions and if needed, can ban the production of a chemical before it even enters the marketplace.


According to the EPA, chemicals are categorized either as an “existing chemical” – something that was on the market before the enactment of the TSCA – or a “new” chemical, which is any substance that is not yet on the TSCA inventory. Prior to the manufacturing and importing of a new chemical for general commercial use, a notice must be filed with EPA.


The inventory contains 86,631 chemicals, of which 42,039 are active.


When it comes to setting screening levels, there are instances when the federal government takes the lead and EGLE follows suit. Ethridge said if the EPA changes its screening levels for certain chemicals, EGLE will adhere to these changes across its permits even if the standing permit was using a previously set screening level.


That's exactly what occurred with the chemical ethylene oxide (EtO), a gas used in the large-scale sterilization of medical equipment. EtO is a toxin that has been regulated by the state of Michigan since 1982, and has been listed on the EPA's Hazardous Pollutant List beginning in 2016. That year, the EPA updated EtO’s hazard level from a “probable human carcinogen” to a “human carcinogen,” and increased its lifetime inhalation cancer risk estimate. The studies in which the EPA adjusted its screening levels revealed that cumulative exposure over many years increases one's risk of non-Hodgkin lymphoma, myeloma, lymphocytic leukemia, and breast cancer.


Such testing operations have taken place at companies such as Valiant in Grand Rapids and Centurion Medical, Inc., in Howell.


EGLE’s previous Initial Risk Screening Level for EtO of .03 micrograms established in 1982 was updated in January 2017 to .0002 micrograms – which is 150 times lower than the previous initial risk screening level. As a result of this change, the AQD put Valiant and Centurion under new scrutiny – even as they operated within the limits of their current permit, and permit re-issuances depended upon the stipulation that the facilities adhered to the new lower screening levels for compliance.


Ethridge said that harmful exposure to EtO was most acute around Valiant in Grand Rapids, which was working off an air quality permit first issued in 2005.


“Valiant was the state’s largest emitter of EtO,” explained Ethridge. “In 2018, EGLE concluded after a lengthy investigation that cancer rates in a neighborhood near the plant were higher than the national average.”


After this modeling study conducted under Ethridge’s supervision, the impacted area at the time demonstrated an average level of .3 micrograms per cubic meter of ethylene oxide in the outdoor air, far over the limit of the EPA’s new limit of .0062 micrograms per cubic meter in outdoor air.


In December 2019, Valiant signed a consent order to stop sterilizing medical devices using EtO by December 31, 2020. The company stopped all operations by January 2020, and paid a penalty of $110,000 to EGLE to conduct monthly air sampling for several months after the plant closed.


As far as the case with Centurion, the air quality division of EGLE issued the company a permit to install in 2017, using the previous screening level of .03 micrograms to determine