Rome, Feb 21 (IANS): Temporary restrictions were enforced in northern Italy, especially the Lombardy region, on Tuesday in response to persistent high levels of air pollution.

These measures were initiated after air quality indicators exceeded the limits stipulated by domestic and European legislation for particulate matter (like particles with a diameter of 10 micrometers or less, or PM10) and other pollutants for four consecutive days, regional authorities said.

A Level-1 ban entered into force in eight provinces of Lombardy, including the regional capital Milan, early on Tuesday. It prohibits all Euro 0 and Euro 1 vehicles, as well as Euro 2, Euro 3, and Euro 4 diesel vehicles in urban areas with more than 30,000 inhabitants from 7:30 a.m. to 7:30 p.m, Xinhua news agency reported.

The Euro emissions standards, labeled from Euro 0 to Euro 6, are set by the European Union to limit the amount of exhaust emissions of newly-sold vehicles. They specify the maximum levels of harmful gases and particles that vehicles can release into the environment.

Additionally, restrictions in Lombardy further prohibit heating homes above 19 degrees Celsius, using wood generators for domestic heating, and spreading fertilisers and slurry on land in farms.

Authorities in the western Piedmont region also imposed similar restrictions on diesel vehicles from Euro 3 to Euro 5, which were banned in Turin and surrounding areas until at least Wednesday.

These measures were adopted based on air pollution data collected across Italy.

According to data released on Tuesday by IQAir, a Swiss company providing air quality monitoring, the PM2.5 concentration in Milan currently exceeds the World Health Organisation's annual air quality guideline value by about 20 times, making it one of the most polluted cities in the world these days.