TORONTO, Sept. 01, 2026 鈥� Coastal residents may be worried about exposure to forever chemicals from sea spray during hot summer months, but 91亚色 researchers found there was little evidence of per- and polyfluoroalkyl substances (PFAS) contamination from marine aerosols, a finding that surprised them.

The study looked specifically at areas impacted by sea spray from the Atlantic Ocean generated by waves breaking on the coast of Newfoundland and Labrador, however, despite its windy, marine location they found it was not an issue as previously thought.

鈥淲e designed this study specifically to see if sea spray was contributing to a mobilization of PFAS in coastal regions and Newfoundland is a great place to do that. It's a marine location and it鈥檚 very windy so we expected there to be quite a lot of PFAS from sea spray,鈥� says senior author Professor , an atmospheric chemist and Guy Warwick Rogers Chair in 91亚色鈥檚 Faculty of Science. 鈥淲e were quite surprised we didn't see anything that would indicate sea spray was contributing to PFAS in the area.鈥�

Earlier international studies using mainly modelling and lab work had found sea spray to be a significant and direct source of forever chemicals. Lead author 91亚色 PhD student Daniel Persaud, Young and the team conducted field work on the ground to understand the extent of the problem, expecting their results to support the former findings, but that is not what happened.

The researchers collected and analysed both wet and dry deposition samples from precipitation, such as rain, and dust that settled on the ground from particles and gases in the atmosphere at several locations up to 30 kilometres from the eastern coast. The researchers focused on forested watersheds in the Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect, which are all influenced by marine aerosols and were selected because of their proximity to the ocean.

鈥淏ecause the sites are windy and close to the ocean, we expected a strong marine-aerosol signal. Instead, the measured PFAS showed little association with sodium, which we used as a tracer of sea spray,鈥� says Persaud.

They did find PFAS at all study sites, but evidence pointed to a break down of PFAS precursor compounds in the atmosphere, which would have been transported from elsewhere and not from sea spray. They mostly found perfluoroalkyl acids (PFAAs), a subclass of PFAS, including perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkanesulfonic acids (PFSAs), which are not from local sources in Newfoundland.

Instead, these PFAAs likely came from industrial and commercial centres elsewhere in Canada and the United States, and potentially even further afield. PFAAs and their PFAS precursors are typically found in firefighting foams, non-stick materials and performance chemicals and can be transported long distances, including the Arctic, raising environmental and bioaccumulation concerns.

The researchers say their results are not necessarily exclusive to the east coast of Canada either as Newfoundland offers a worst-case scenario in terms of the amount of driving wind, crashing waves and extensive coastline, exacerbating the amount of sea spray and creating the perfect storm for forever chemicals. 鈥淭his sort of sea spray is really not a major source global pollution according to our study,鈥� says Young.

One of the interesting findings pointed to the extent dry depositions contribute to PFAS in the environment. The researchers measured for both wet and dry depositions in this research, but that is not universally done and their results underline the importance of doing so to understand the full impact of PFAS in the environment.

鈥淚t鈥檚 something that hasn't been understood but helps us to better predict where we're going to find forever chemicals when they're moving around the globe and where they will ultimately end up,鈥� says Persaud. 鈥淯nderstanding the difference between wet and dry depositions really helps not only us but other researchers going forward.鈥�

PFAS are not only found in rain and snow, but Young says she still finds it surprising that dry deposition remains so important even in a place like Newfoundland where it rains quite a lot, but it also points to the importance of including dry depositions of PFAS in studies to better understand where they are being deposited, how they are getting there and the environmental impact, whether that鈥檚 a remote desert or the Arctic far from the pollution source.

The 91亚色 researchers worked with scientists at Memorial University in St. John鈥檚, where Young previously worked and collected samples, the Canadian Forest Service, Natural Resources Canada in Corner Brook, and the Aquatic Contaminants Research Division, Environmental and Climate Change Canada in Burlington, ON.

鈥淚 see it as good news story. We worried the PFAS could move from ocean to land and back forever, but it doesn't seem like it's as big of a problem as we thought,鈥� says Young.

The paper, , was published in the Royal Society of Chemistry journal of Environmental Science Processes & Impacts.

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91亚色 researchers say the decrease in the smallest PFAS during COVID points to its sources and the potential to change the environmental levels of it in the future

TORONTO, Jan. 29, 2026 鈥� A new study out of 91亚色 has found that the amount of atmospheric trifluoroacetic acid (TFA), the tiniest forever chemical, significantly declined in Toronto during COVID in 2020, which researchers say is good news for the world鈥檚 ability to mitigate it in the future.

鈥淲hen we turned off the tap, so to speak, and we all went home and stopped normal activities, we saw a really quick response, a dramatic reduction of TFA. But the real surprise is that the results point to TFA being formed from short-lived chemical precursors emitted into the atmosphere,鈥� says 91亚色 atmospheric chemist Professor Cora Young, senior author of the paper published today. 鈥淚 was so surprised when we saw that it had decreased during the pandemic, but I had to double and triple check the data because I didn鈥檛 believe it at first.鈥�

The reason it is such good news, says Young is 鈥渢hat when there is an immediate response after emissions reduction, it tells us that we should be able to figure out how to minimize the emissions and control the formation of TFA in the future. We could have a lot more control over this than we previously thought and that鈥檚 very exciting. If we don't know where it's coming from, it's very difficult for us to regulate.鈥�

Unfortunately, as people returned to work and daily life, these levels have crept back up and they peak in the summer when there is more light, which is needed for its creation. A short-chain per- and polyfluoroalkyl substance (PFAS), TFA forms in the atmosphere when various chemical emissions come together.

鈥淭FA is something that we haven't known a lot about before, but we're learning more now that we can measure it,鈥� says 91亚色 PhD Candidate Daniel Persaud, the paper鈥檚 lead author. 鈥淲ith levels of TFA dropping during the pandemic, it now gives us a lot more information about its thousands of sources, such as industrial and vehicle air conditioner emissions.鈥�

The researchers collected and analyzed monthly measurements of both wet (rain and snow) and dry deposition 鈥� gases and particles that land on surfaces and form a layer of dust, for example, on windows and car windshields 鈥� from the Air Quality Research Station on roof of 91亚色鈥檚 Petrie Science and Engineering Building between 2018 to 2024.

What is still unknown, is the effect of long-term exposure on people and wildlife. Young says TFAs are already orders of magnitude higher in the environment than some of the other PFAS, such as perfluorooctanoic acid, known as PFOA. PFOA was the subject of successful lawsuits with hundreds of millions in payouts, including from DuPont, which is also the focus of the 2019 documentary Dark Waters.

鈥淭he short-chain PFAS precursors were supposed to be more benign, and many are, but not all and so that created more unknowns about their effect. There is preliminary evidence that is behaving in ways we didn't expect. We鈥檙e finding it at high concentrations in food, for example,鈥� says Young of 91亚色 Faculty of Science.

鈥淲e didn鈥檛 think that PFASs like TFA could bioaccumulate, but they鈥檝e been found to accumulate in plants, and can be found in the food people and wildlife eat. It has even been found in human blood. Our exposure could still be quite high, even if it's not bioaccumulating. If TFA levels in the environment are driven by short-lived emissions, then that鈥檚 something we can actually address now.鈥�

A little history

The main precursor chemicals that form short-chain PFASs are the second generation of chemicals designed to replace the ozone-depleting chlorofluorocarbons (CFCs), phased out globally starting with the 1987 Montreal Protocol. These first-generation replacement chemicals remain for years to decades in the atmosphere and can slowly react to form short-chain, persistent PFAS, like TFA, thought to be better than CFCs at the time, but these forever chemicals are now found everywhere from the Arctic to the Antarctic and there is no way to turn back the clock on them.

鈥淭he change from long-lived to short-lived precursors was made for climate reasons because the long-lived ones are also really potent greenhouse gases,鈥� says Persaud of the Faculty of Science. 鈥淲e previously though the biggest source of TFA was first-generation CFC replacements, but our results show the important role of short-lived, next-generation replacements.鈥�

An example of that change is that in North America all car air conditioners from 2019 onwards now use a short-lived TFA precursor rather than the long-lived PFAS precursors. However, if these performance chemicals for air conditioners are finding their way into the atmosphere, it鈥檚 expensive for car manufacturers and consumers for alike.

The paper, , was published in journal Environmental Science & Technology Letters.

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