Research into PFAS in flue gases led to new discoveries

In a research project, IVL Swedish Environmental Research Institute tested new methods for measuring the environmentally hazardous substance PFAS in flue gases from Swedish waste incineration plants. The measurements show low levels of PFAS. Instead, it is freons that dominate emissions. The discovery raises questions about how long persistent fluorinated substances, which were banned in the 1980s, will remain in society's material flows.

Freons were previously used in products such as insulation – when they were still permitted. In older buildings they can still be present, and can be released when these buildings are demolished and the resulting waste is sent for energy recovery. At the same time, we cannot completely rule out the possibility that some new formation may occur during combustion, or that background levels in the surrounding air may affect the results. For instance we see freons in certain background measurements, such as indoor air in laboratory environments. Overall, demolition waste still appears to be a likely explanation for the presence of freons in the flue gases, says Johan Strandberg, project manager at IVL Swedish Environmental Research Institute.

The Swedish project, supported by the US EPA and the Swedish Environmental Protection Agency, is the first to measure PFAS in flue gases from waste incineration plants. Three different measurement methods were tested, under real operating conditions.

The measurements show that the levels of many individual substances vary greatly over time and between different sampling points in the chimney. For the most volatile substances, the results are more consistent, but for others, a random sample would often be misleading if, for example, one wanted to describe annual emissions.

When levels fluctuate this much, it becomes difficult to use individual point measurements as a basis for conditions or follow-up. It is likely and reasonable that PFAS emissions to air will be regulated. But then we need monitoring that is designed to also capture variation over time, says Johan Strandberg.

Since PFAS are already present in society's material flows, they will continue to appear in waste streams for many years to come – in the same way that freons are now found as a result of previous use. For this reason, it is important to develop methods that enable facilities to monitor and track their emissions reliably, even when concentrations are low.

Our study shows that it is already possible to measure these substances in flue gases, but also to discover the limits of how the results can be used. This informs us on how future measurement programmes can be designed so that emissions of persistent fluorinated substances can be monitored more systematically, says Johan Strandberg.

Download the report: Assessing PFAS flue gas sampling standards in operation External link, opens in new window.

In case of questions, contact:
Johan Strandberg, johan.strandberg@ivl.se, tel. +46 (0)10-788 65 98
Emelie Karlsson, advisor, Swedish Waste Management, emelie.karlsson@avfallsverige.se