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France's fight against winter smog

In the Arve valley, the speed limit is reduced by up to 40 km/h. Three sections of motorway are affected by the measures. The aim is to avoid the threat of air pollution and the associated driving bans.

As it does every year, the Haute-Savoie Department is reducing the speed limit on some stretches of the Arve valley to prevent air pollution and to prevent the undesirable activation of the temporary environmental zone. Since 1 November, three sections of motorway in the department located in the Alps near the Swiss border have been affected. These are the A 410 between the Pass Évires and the junction with the A 40 at Scientrier, on which a reduction of the maximum speed limit from 130 to 110 km/h is taking place. The same measure has been taken for the A 411 from the Vallard customs office on the border with Switzerland to Le Fayet. On the RD 19 between Ayse and Marignier, the speed limit is even reduced to 90 km/h. The measures will run until the end of March.  
In winter there is often less air exchange, which means that particulate matter and other pollutants accumulate directly at the source. Normally the exchange takes place between different layers of air, as warm air rises from the ground and mixes with overlying cold air. In so-called "low-exchange inversion weather conditions", which often occur in winter, cold air is directly on the ground and cannot escape because it is heavier than the warmer air above. The winter smog generated in this weather situation is very harmful to health because of the increased nitrogen oxide and fine dust levels, and in winter leads to increased activation of temporary environmental zones in France.  
Compared to previous years, the measures are proving successful: ATMO France, which monitors air quality in the Auvergne-Rhône-Alpes region, has measured a significant improvement in air quality in conjunction with reduced speeds. Nitrogen dioxide concentrations have thus fallen by 12% in recent years. Particulate matter has been reduced by a similar amount of 10 to 12% and 8% savings have also been achieved in CO2 emissions.  
While the measures are likely to cause annoyance among commuters in the region, the activation of the low emission zone, which includes 41 towns and municipalities along the 80km stretch of the river, would significantly increase traffic congestion. Depending on the air quality, vehicles with or without stickers, i.e. diesel up to Euro 5, will be banned.  
If, despite these measures, driving bans are threatened in the Arve valley, you will find up-to-date information as always in our Green-Zones App. Of course, this also applies to other temporary and permanent environmental zones in France and Europe.