The dirtiest air in Wales is a lot cleaner

1 minute read


A few months ago I looked at levels of Nitrogen Dioxide (NO2) in Cardiff - in the pedestrianised city-centre and on the busy Newport Road. Now it’s time to see what’s been happening during the lockdown in the Welsh village of Hafodyrynys, famous for having some of the dirtiest air in the UK because of the heavy traffic that runs through it.

NO2 is a major contributor to air pollution and is generally caused by traffic.

While the daily trend remains the same in Hafodyrynys, with the morning as the dirtiest when roads are busiest with a smaller peak in the evening, the levels of NO2 dropped dramatically once lockdown began.

Levels of NO2 in Hafodyrynys

By the first week of May the amount of NO2 in the mornings was almost half of what it was two months earlier. In early June, when the end of Lockdown was imminent if not official it started to climb again.

Levels of NO2 in Cardiff

Similar trends are visible in Cardiff city-centre (with data from a station that admittedly sits in a pedestrianised area of the city centre rather than on the side of a busy road). Daily peaks are a quarter of what they were before the Lockdown, but most strikingly the worst hour of dirty air in Cardiff is almost better than the cleanest hour in Hafodyrynys.