PM10 (fine particulate matter)
The sum of all the particles suspended in the atmosphere is referred to as PM (fine particulate matter). The source of the particulate can be anthropic or natural. In an urban environment the most important causes of high dust concentration are traffic emissions, and in particular the use of diesel engines and motorcycles. A smaller percentage is due to old tires and car brakes.
During winter, emissions from heating systems add to the PM, in larger amounts due to materials such as gas oil, coal, mineral oil and wood, and to a lesser extent, methane. The particulates are classified according to their size and their capacity of penetrating the respiratory tract, causing harmful effects on people. For the dust that can penetrate the upper part of the respiratory system (such as the nasal cavity, the pharynx and the larynx), and with a diameter of 10 μm or larger, the European norm accepted also in Italy, provides a limit of 50 mg/m3, which may not be exceeded more than 35 times a year.
The Mayor is indicated by a law of the Region of Tuscany as the qualified authority to set up interventions to limit the emissions of the polluters, already starting from the 15th day that the concentration limit of PM10 of 50 µg/m³ is exceeded. All the municipalities of the agglomerate of Florence have issued an order to limit the emissions of heating systems during winter, and of traffic all year round.
To limit the emissions of heating systems, the municipalities are obliged to reduce the daily heating period to a maximum of eight hours a day. Also some rules are introduced concerning the maximum temperature, depending on the type of building this is limited to 17 or 18 degrees Celcius. Excluded are the heating systems of hospitals, clinics or nursing homes, including hospices or homes for minors and elderly people, schools and nurseries.
To limit traffic emissions, there are Traffic Restricted Zones (Zona a Traffico Limitato or ZTL) which prohibit entry in the city center to certain vehicles at certain times of the day.
Comune di Firenze - Palazzo Vecchio, P.zza Signoria 50122 FIRENZE - P.IVA 01307110484
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