How tight should the air pollution laws be? There is a lot of argument and concern not only over health issues but over costs and technical limits. With an overhaul of air quality laws due within a year in Europe, health advocates are calling for the European Commission to resist pressure to tone down the EU’s pollution standards and instead replace them with stronger UN guidelines. The call for tougher anti-pollution measures came two days after a report by the European Environment Agency showed that nearly one-third of urban residents breathe air that is far dirtier than the law allows. The tally rises to well over 80% when the recommendations of the UN World Heath Organization are applied.