The levels of fluoride in grass in areas around the Alcoa aluminum smelter in Reyðarfjörður, East Iceland, proved to be just below the guideline limit in the Environment Agency of Iceland’s third round of testing this summer.

The pollution levels have dropped compared to the first two rounds of testing, when fluoride was found to be above the guideline limit on average in the eight locations tested, two of which are in the town of Reyðarfjörður, ruv.is reports.

However, decrease in pollution is attributed to rainfall in the days preceding the testing, whereas there hadn’t been any precipitation in the area prior to the first two rounds. The level of wind may also have had an impact.

The Environment Agency is therefore looking to measure the concentration of fluoride in grass over a longer period of time and will continue testing the levels throughout the summer.