In a groundbreaking study spearheaded by researchers at York University, atmospheric levels of trifluoroacetic acid (TFA)—an elusive yet persistent chemical classified among the so-called “forever chemicals”—experienced a noteworthy decline throughout the COVID-19 pandemic period in Toronto. This revelation not only marks a significant milestone in atmospheric chemistry but also illuminates new avenues for mitigating such enduring environmental pollutants. The study’s findings, published recently in the journal Environmental Science & Technology Letters, highlight how shifts in human activity have a profound, immediate impact on the atmospheric concentration of such chemicals, presenting a promising path toward effective regulatory control.
The dramatic drop in atmospheric TFA levels during the pandemic shutdown was unexpected. Professor Cora Young, a leading atmospheric chemist at York University and senior author of the study, expressed initial skepticism upon seeing the data. “The swift response of TFA concentration to reduced emissions was astonishing,” she stated, emphasizing that the data underwent rigorous verification processes before reaching these conclusions. The diminishment of TFA during a period of unprecedented global industrial slowdown indicates that the compound is formed largely from precursors with relatively short atmospheric lifetimes, contrary to prior assumptions that it predominantly stems from long-lived chemicals.
This discovery carries profound implications for environmental management. The immediate responsiveness of TFA levels to emission reductions means that regulatory strategies could directly influence its atmospheric prevalence. Professor Young elaborated, “If we can identify and minimize the short-lived emissions responsible for TFA formation, we have a tangible opportunity to control this pollutant’s cycle.” Historically, the persistence and diffuse sources of TFA had rendered control efforts nearly impossible. Now, the window is open to design interventions that could significantly attenuate TFA’s environmental footprint.
However, the research also documented a natural resurgence of TFA concentrations as societies resumed normal activities post-pandemic, with peak levels coinciding with summer months. This seasonal trend correlates with increased sunlight, a key driver of atmospheric chemical reactions that generate TFA. As a short-chain per- and polyfluoroalkyl substance (PFAS), TFA formation is intricately linked to complex interactions among various atmospheric precursors, which catalyze photochemical transformations under favorable conditions.
Daniel Persaud, a York University PhD candidate and the study’s lead author, highlighted the importance of newly available measurement technologies in unraveling the enigma of TFA’s environmental cycling. By leveraging sophisticated monitoring at York’s Air Quality Research Station, the team obtained monthly datasets encompassing both wet and dry deposition processes over six years, from 2018 through 2024. This extensive data collection has provided unprecedented insights into how atmospheric TFA is deposited onto surfaces via rain, snow, gases, and particulate matter, painting a comprehensive picture of its dynamic environmental behavior.
Despite these advances, significant knowledge gaps remain regarding TFA’s long-term effects on ecosystems and human health. Professor Young noted that TFA concentrations in the environment have already surpassed those of longer-chain PFAS compounds such as perfluorooctanoic acid (PFOA), a notorious chemical involved in high-profile lawsuits and extensive regulatory scrutiny. Unlike PFOA, the biological accumulation and toxicity profiles of TFA have not been fully elucidated, leaving scientists cautiously vigilant about potential undiscovered risks.
What complicates matters further is the evolving landscape of PFAS chemistry. TFA arises as a breakdown product of “short-chain” PFAS precursors introduced as safer replacements for the older, ozone-depleting chlorofluorocarbons (CFCs). These second-generation chemicals were adopted globally following the 1987 Montreal Protocol to mitigate ozone layer damage. While these alternatives have significantly reduced atmospheric lifetimes compared to their predecessors, their transformation into persistent byproducts like TFA underscores a new layer of environmental challenge that demands closer scrutiny.
The shift from long-lived to short-lived PFAS compounds was motivated primarily by climate considerations. Long-lived CFC replacements are potent greenhouse gases, and their atmospheric persistence exacerbates global warming. Daniel Persaud explained that initial assumptions positioned the first-generation CFC substitutes as the primary sources of TFA, but the study’s findings reveal a critical role played by newer, short-lived chemicals. This insight forces a reevaluation of how industrial chemical emissions are regulated to balance climate benefits with the unintended generation of persistent chemical pollutants.
Intriguingly, the widespread adoption of these short-lived PFAS precursors is evident in everyday technologies, such as automotive air conditioning systems in North America, which transitioned entirely to these chemicals by 2019. Although these substances offer performance and environmental advantages, their atmospheric release and subsequent breakdown produce TFA, representing hidden costs borne both economically and environmentally by manufacturers and consumers alike.
The study’s methodological rigor and long duration provide a robust foundation for future work aimed at reducing TFA’s environmental impact. By establishing that TFA levels respond quickly to emission changes, researchers have a clearer target for emission control policies, potentially leading to improved atmospheric and public health outcomes. Indeed, the ability to measure and monitor TFA continuously will empower policymakers to assess the effectiveness of regulatory interventions in real-time.
While the bioaccumulation potential of TFA was previously considered negligible, emerging evidence suggests otherwise. TFA has been detected at elevated concentrations in plants and various food sources, and alarmingly, it has even been found in human blood samples. This revelation challenges previous paradigms and implies that human exposure pathways could be more significant than understood, underscoring the need for intensified toxicological research.
The findings from this York University study thus present a complex narrative where human industrial activity, environmental chemistry, and public health intersect. The unprecedented drop in TFA during the COVID-19 pandemic offered a natural experiment, highlighting both the responsiveness of this compound to emissions and the pressing need to better understand its ecological and physiological implications. As urban centers scale back emissions temporarily, the resulting environmental insights are invaluable in guiding future regulations on PFAS and their precursors.
In summary, the research encapsulates a crucial turning point in the study of atmospheric PFAS compounds. It disrupts the previously accepted understanding of TFA’s formation and persistence, opening prospects for targeted intervention through emission control. This evolving scientific knowledge base sets the stage for a more proactive environmental stewardship approach—one that integrates chemical monitoring, regulation, and health impact assessments to combat the pervasive issue of “forever chemicals” in the Anthropocene era.
Subject of Research: Not applicable
Article Title: Atmospheric Removal of Trifluoroacetic Acid by Dry and Wet Deposition: A Multiyear Analysis in Toronto
News Publication Date: 29-Jan-2026
Web References:
https://pubs.acs.org/doi/10.1021/acs.estlett.5c01100
References:
Young, C., Persaud, D., et al. Atmospheric Removal of TFA by Dry and Wet Deposition: A Multiyear Analysis in Toronto. Environmental Science & Technology Letters. 2026.
Image Credits: York University
Keywords:
Atmospheric science; Environmental chemistry; Industrial chemistry; Atmospheric chemistry; Atmosphere; Climatology; Chemistry
