Per- and polyfluoroalkyl substances (PFAS) — frequently referred to as “forever chemicals” — continue to top newscasts as a major environmental and health concern, with possible links to higher cholesterol levels, decreased vaccine response in children and an increased risk of cancer.

Because PFAS readily dissolve in water and are highly mobile, they have been detected at relatively high frequencies in water supplies and recreational water bodies. As a result, initial PFAS regulations were focused on establishing safe levels in water to prevent ingestion of these compounds as well as dermal contact. The regulatory focus then turned to impacted soil, with some states establishing limits to prevent ingestion of and dermal contact with PFAS-containing soils and the leaching of these chemicals into groundwater. Now, questions are being raised about possible inhalation exposures and the need to regulate PFAS in air.

Addressing PFAS in air might be more complex than water or soil as there are many different sources and transport pathways. These forever chemicals can enter outdoor air through stack emissions of industrial processes, waste management facilities — landfills, wastewater treatment plants — or outdoor uses of PFAS-containing materials (such as firefighting foam). Also, they can be released into indoor air where industries produce or use PFAS and where stain- or water-resistant products — carpets, clothing, food packaging, paints, etc. — are used. Some PFAS are volatile and have potential to migrate from underground water and soil sources into indoor air.

Not only are there many potential PFAS air sources, but the degree to which these sources pose health risks is poorly understood. For example, there are insufficient toxicological studies to establish inhalation toxicity criteria for PFAS; soil and water standards are based on ingestion toxicity. Broadly accepted laboratory analytical methods for measuring PFAS in air are still being developed, meaning limited data is available for PFAS in air as compared to water and soil. With ongoing PFAS research being funded by the U.S. Environmental Protection Agency (EPA) and others, a clearer understanding of the relative health significance of the various PFAS air sources should eventually emerge.

In the meantime, the EPA has set water and soil guideline values for three PFAS (PFOA, PFOS and PFBS) out of the more than 4,700 PFAS produced and used in society since 1950 — but no air guidelines yet. However, the limits established by the EPA are not enforceable and, as some state toxicologists believe, not protective enough. Thus, many states have taken PFAS management into their own hands.

In February 2020, the Environmental Council of the States (ECOS) published a white paper based on state surveys that compiles existing state PFAS standards, advisories and guidance criteria and highlights various approaches states are taking to address PFAS. The paper also provides direction for future regulatory activities. While many states are codifying legally enforceable standards or providing nonenforceable guidelines for select PFAS, only three states have published PFAS air criteria.

Michigan (initial threshold screening level)

  • PFOA Advisory level: 0.07 µg/m3
  • PFOS Advisory level: 0.07 µg/m3

New Hampshire (ambient air)

  • APFO Regulatory level (24-hour): 0.05 µg/m3
  • APFO Regulatory level (annual): 0.02 µg/m3

Texas (occupational health)

  • PFOA Advisory level (based on annual average): 0.005 µg/m3
  • PFOS Advisory level (based on annual average): 0.01 µg/m3

When ECOS asked states what the greatest impacts on state PFAS regulations would be in the future, the first item listed was how to develop and apply guidelines in less-explored media like air emissions. There is no doubt, then, that other states will soon follow suit as these established PFAS air standards draw attention from regulatory agencies as well as the public.

Establishing PFAS air standards for industrial processes and for PFAS incineration will be an important factor in instituting air permit requirements. The 2020 National Defense Authorization Act requires the military to conduct PFAS incineration that complies with the Clean Air Act, which implies meeting air emission permit requirements. However, there are no federal standards for PFAS in air to assess whether this requirement has been met. The absence of such federal standards could place the burden of developing scientifically defensible ones on the states.

As conversations concerning PFAS evolve and guidelines and regulations emerge, it is important to track what information and standards exist at local, state and federal levels as they will likely guide the regulations that are promulgated in the near future. Partnering with a knowledgeable team — one with technical skills and experience with PFAS in all media — provides the necessary guidance to navigate a changing PFAS landscape. 


On the heels of the EPA’s PFAS guidelines, private industry, government organizations and the military have searched for and implemented smart, successful processes to help tackle this challenging PFAS issue as regulations continue to unfold. See what solutions are available.

Explore PFAS and Beyond

Kanan Patel-Coleman, a project manager and senior risk assessor at Burns & McDonnell, works with a team of human and ecological risk assessors to address environmental exposures from chemical releases. She has experience in health risk assessments, vapor intrusion investigations, product safety assessments and project management.