Air pollution is caused by a number of sources and human activities—such as industry and transport—and can have a detrimental effect on public health and the environment. Air pollution is said to be a problem at the local, national and international levels. Air quality in the UK is largely governed by the EU’s Ambient Air Quality Directive (2008/50/EC). This Directive sets legally binding limits for concentrations in outdoor air of major air pollutants that impact public health, such as particulate matter and nitrogen dioxide. In February 2017, the European Commission gave the UK a final warning over its failure to meet air pollution limits for nitrogen dioxide. In July 2017, the Government published its air quality plan. Along with £2.7 billion committed to improving overall air quality and cleaner transport, the plan required local authorities to develop their own plans to reduce air pollution in their areas.