The Effect of Sea Breezes on Air Pollution Dispersion

Swansea is the wettest city in the UK and has an NO2 problem due to traffic. It benefits from an advanced air quality monitoring system. In a coastal area like Swansea, the difference in heating can have a large impact on the weather by the formation of the sea and land breezes. These, coupled with the presence of a windier climate in general, impact upon the dispersion of pollution in the city. Nevertheless, mountains are associated with up and down wind (katabatic airflow), causing air containing pollutants to spread horizontally, reducing the potential for dispersion. The aim of this research is to investigate sea and land breezes of the city of Swansea in relation to topography and in conjunction with urban air quality, together with pollutant exceedences associated with specific weather conditions. Such a phenomenon clearly occurred on 1st and 2nd June 2008 during a summer of otherwise rare sea breezes occurrence. High concentrations of NO2, O3 and PM10 were recorded during the middle of the night between 23:00 hours on 1st June and 01:00 hours on 2nd June, when the sea breeze changed into a katabatic wind, returning Swansea’s pollutants to the city under these specific meteorological conditions.