That means that 50 percent of privately owned cars will be banned from driving within the limits of the M-30 ring road motorway on specified days according to their registration numbers. Vehicles with registration plates ending in an even number can drive within the area on even days, and vehicles with registration plates ending in an odd number, on odd days.
In other words, only vehicles with a registration number ending in an odd number will be allowed to drive within the specified limit on Thursday, December 29th, and only those with an even number on Friday, December 30th, with the pattern continuing until the restrictions are lifted.
The restrictions apply between 06:30 and 21:00. There are a number of exemptions however: ‘Zero emission' vehicles, hybrids, motorized scooters, vehicles for those with a disability, cars with a high occupancy (classified as three or more occupants), and public transport will not be covered by the ban. A full list of exemptions is available in Spanish here.
A maximum speed limit of 70 km/h on the city's main roads introduced earlier this week remains in place, as does a parking ban in areas covered by SER parking meters.
The first round of measures kicked in on Tuesday because the levels of nitrogen dioxide in the city's air exceeded 180 micrograms per cubic metre on December 26th. Phase three was subsequently activated because the levels exceeded 200 micrograms per cubic metre in the following days.
The measures will be in place until the contamination reduces, but calm weather in the city has not helped the cause.
If the nitrogen dioxide levels reach 400 micrograms, the City of Madrid could activate phase four of its anti-pollution measures, which includes reducing traffic on the M-30 by 50 percent and banning taxis from driving in the city centre.