MSP Mark Ruskell advocates a 20mph speed limit in towns, stating he would not put his family at risk on polluted streets (“Demands for 20mph limits in fight against ‘health crisis’, The Herald, September 13). In that case, I presume he’ll avoid Edinburgh’s Cowgatehead, a through route that picks up additional pollution from overhead George IV Bridge.

Last year Edinburgh City Council officials advised against a proposal for a hotel of up to 11 storeys beside the Central Library, claiming that it would create a “canyon effect”, increasing pollution “where there are already local air quality concerns”. Citing poor, outdated data collection, they added: “This site could breach the air quality standards even without the proposed development.”

Despite this, the Scottish Environmental Protection Agency (Sepa) offered no objection, even although there had been no environmental impact assessment as required under Scottish regulations and EU law. Sepa said the developers’ air quality impact assessment had “demonstrated that the proposed development will have a negligible impact on local air quality”. Mr Ruskell’s proposals for urban speed limits might be more convincing if he were to ask for an investigation into a state regulator that, in this case, seems unwilling to regulate.

David J Black, 6 St Giles Street, Edinburgh.