Research carried out has shown that tree lichen in the city centre area has recovered due to the improvement in air quality. In the cleanest areas bordering the city centre area there has been a reappearance of pollution-sensitive lichen species, which disappeared over half a century ago as a result of smoke pollution.
You can pick forest mushrooms in Helsinki, but not everywhere
Those who pick forest mushrooms must not only be able to identify the mushroom species, but also be able to assess the places where it is sensible to pick mushrooms. Mushrooms growing along the roadside or in grass areas in parks often absorb harmful substances such as heavy metals.
The lead, mercury and cadmium content of mushrooms in Helsinki Central Park has been studied. In the southern part of the park even the mushrooms in the forest have heavy metal contents that exceed the guide values, so they should not be picked for eating.
However, in practice, the amounts of mushrooms used are so small that there is no danger of poisoning. The contents of fungus growing in the grass, such as field mushrooms, can be considerable.
The recommended areas for fungus forays in Helsinki are the Haltiala forest area, where the Central Park becomes wide enough for protection against air pollution, and the forests in East Helsinki apart from those near the main traffic thoroughfares. The outdoor recreation areas of Nuuksio and the Sipoonkorpi forests extend the possibilities for Helsinki mushroom pickers.