Polemical method used in Madrid

The last thursday 29, the town hall of Madrid imposed a law to reduced NO2 emissions because it has the cuadruple times the number of emissions stablished. This law was based on banned driving cars with pair number. One day cars with pair plate could drive and the next day, cars with odd plate could drive. This law reduced the NO2 emissions in more than 20% but this coused a popular disagreement and a lot of replies. Because of that th town hall disolve this law but, thay set that if the emissions increased again they maybe imposed the law again.