The migration routes of pollution: How ozone, Saharan dust and wildfire smoke cross borders
Pollution crosses any border. Residents of Seville saw this in August when the huge Niebla wildfire in Huelva province collapsed air quality levels in the Andalusian capital. Madrid residents experienced it days earlier when the regional government asked them to stay indoors because smoke was arriving from out-of-control fires in the Sierra Oeste and Ávila province. This pollution, laden with harmful particles, travels tens or hundreds of miles, and sometimes crosses countries and oceans. “Air quality in our cities, towns or countries is not only influenced by local activities but can be affected by pollution from neighboring or quite distant nations,” explains Ian Marnane, head of the Environment and Health Unit at the European Environment Agency (EEA).

© NICOLAS TUCAT (AFP)
