Many parts of southern and eastern Finland are affected by the smoke originating from forest and peat fires to the north and west of Moscow across the Russian border.

According to the Finnish Meteorological Institute (FMI), air quality is worst in eastern areas. The smoke haze was, however, clearly visible as far west as the city of Tampere.

Small particle content in the air was high in the whole region on Thursday. Forest fires increase the content of small particles in the air, as well as irritating hydrocarbons. The FMI says that sunlight reacts with the smoke to produce harmful ozone in the lower atmosphere. This can result in symptoms, especially those with cardio-pulmonary conditions, and those who are afflicted are advised to stay indoors.

The FMI says the situation improved on Thursday night, as rain and thundershowers moved into the area from the south.