PFAS in Gospić and what an air-quality index cannot see

In groundwater from monitoring boreholes beside the illegal waste dump at 50 Bilajska Street in Gospić, experts from the University of Zagreb's Faculty of Geotechnical Engineering found PFAS compounds. A further analysis by the Croatian Institute of Public Health (HZJZ) and the Andrija Štampar Teaching Institute of Public Health found the same compounds in samples of the waste itself.^[9] An air-quality monitor, however close to the site, would have recorded none of this. It measures what is in the air, and here PFAS was found in groundwater and in the waste.

The findings are part of an investigation by USKOK, Croatia's anti-corruption and organised crime office, into a number of suspects alleged to have committed environmental and economic offences as members of a criminal organisation. On 9 September, citing public interest, USKOK made the HZJZ opinion on PFAS in the Gospić waste available for inspection.^[3] On 22 September the government presented its clean-up plan. An estimated 44,000 tonnes of hazardous and non-hazardous waste lie on the site, almost 33,000 tonnes of it buried 2.9 metres down and mixed with soil and stone in unknown proportions.^[1]

Water and food: what was sampled

On 9 September HZJZ reported that none of the 73 public water supply samples analysed up to then contained detectable PFAS. By 22 September the count for Lika-Senj County and the island of Pag had reached 111. Every sample met health standards, and none contained PFAS above the limit of determination.^[9][4]

According to HZJZ, the dump lies outside the sanitary protection zones and outside the catchments of the springs that supply the county's drinking water. The institute places PFAS levels in the groundwater around the site at the lower end of what is usually recorded near landfills, and rates the risk to the public supply as low to negligible. That assessment does not cover private wells. They are not part of the public supply or of state monitoring of drinking water, and their owners are responsible for them, although HZJZ has said it will test them too.^[9]

On 28 August HZJZ sampled food from households that grow their own: 32 samples from 13 locations, six within 300 metres of the waste and 26 within 1,000 metres. Lead and nickel, both present in the waste at elevated levels, stayed within permitted limits in every sample. Seven samples were tested for PFAS, and all were below the limit of quantification.^[5] The only non-compliant sample was aronia from a household 1,000 metres away, with 0.065 mg/kg of cadmium, more than twice the maximum of 0.030 mg/kg. HZJZ said that cadmium can occur naturally in soil and that the single result did not allow it to conclude that the cadmium was linked to the dump.^[5]

What the air-quality index measures

The AQI on AirQuality.city is calculated from PM2.5 and PM10 concentrations, and a station's overall rating is set by whichever of the two is worse.^[6] Some official stations also publish NO₂, O₃, SO₂ and CO, but the site shows these separately and they do not feed into the overall index.^[8] Even the best AQI therefore says nothing about PFAS in groundwater or metals in soil, just as a tap-water test says nothing about PM2.5 in the air.

Particle readings say little about where the particles came from, either. A sensor records how much particulate matter is in the air, but the number alone cannot reveal its chemical make-up or prove that it came from a particular site.^[7] A station also describes only its own surroundings, and concentrations shift with wind, rain, local sources and the time of day. One clean hour does not prove there was no pollution episode, and one bad hour does not prove a lasting problem. An unusual PM2.5 or PM10 spike near a dump is worth looking into, but on its own it does not prove where the particles came from, and it says nothing about the water, the soil or the food.

When waste becomes an air problem

A dump can affect the air when something happens on it: when it burns, when wind lifts dust off the surface, when certain substances evaporate from the waste, or when the waste is moved. A great deal will be moved in Gospić. Temporary covering of the buried waste was under way on 22 September, and a contractor had been chosen to take around 4,500 tonnes of loose hazardous waste from beside the silo for incineration outside Croatia. About 650 tonnes of non-hazardous waste in bags is due to be burned as substitute fuel at the cement works in Našice and Koromačno, which hold the necessary permits.^[1][2]

For the work on site, the plan provides for air monitoring before and during the clean-up, covering PM10 and PM2.5, the same two fractions the AQI is built on, as well as total deposited dust and the heavy metals in it. PFAS is to be monitored in groundwater, not in the air. The listed measures include damping down and covering, vehicle speed limits, wheel washing and uncovering the waste gradually, and the plan notes that each parameter is monitored only in the phases where it applies.^[2]

The biggest job is the buried waste. Marija Vučković, the Minister of Environmental Protection and Green Transition, said her ministry preferred to treat it on site: dig all of it up, then separate and characterise it mechanically, working only inside an enclosed system. That option would take 13 months and cost €40 million. The alternative is excavation without pre-treatment, with final treatment abroad.^[1]

What "safe" means

HZJZ described the food in Gospić as safe to eat and the public water supply as compliant with health standards and safe to drink. Those verdicts rest on specific samples: 111 public water samples with no PFAS above the limit of determination, and 32 samples of home-grown food with no sign of general contamination. PFAS was found in groundwater from boreholes right beside the dump.^[4][5][9] All three findings hold at once because they describe different samples from different places.

Sampling of the public supply continues, and HZJZ publishes the results weekly.^[4] Once excavation of the buried waste begins, the plan calls for air to be measured alongside water and soil.^[2]