Pollution is damaging to health but not all places are equally polluted. The level of pollutants can vary substantially over the distance of several metres. It is important to know where higher levels of pollution occur in order to focus our efforts in fixing the problem, or at least in avoiding unnecessary exposure.
One key pollutant is nitrogen dioxide (NO2). Portsmouth City Council and DEFRA maintain a network of sensors around the city. This lets us see where pollution occurs, as well as variations from year to year. It takes the council several months to publish the previous year’s data, so here is the 2016 measurements on a pretty map:
Raw data: measuredno2.csv, References: Portsmouth City Council 2016 Air Quality Status Report
As we can see, pollution is particularly high along the London Road/Kingston Road/Fratton Road route. There are other pollution black spots around Hampshire Terrance and Albert Road. These locations exceed the legal limit of 40µg/m3. Most of the west side of Portsmouth is between 30-40 µg/m3, which is dangerously close to the limit and cannot risk having another significant increase in pollution.
One limiting factor is the government can only afford a limited number of sensors. We might want to know about pollution in other parts of the city. Fancy real time monitoring stations cost an absolute fortune! However, we can use traffic data, existing pollution measurements and computer modelling to predict the level of pollution in other locations. This gives us a broader picture but the results can be less accurate because they rely on the assumptions used in the computer model. Here are the predicted NO2 levels for 2015 from a recently published report:
This shows pollution levels around the naval base, Gunwharf Quays, University of Portsmouth, Queen Street, Stanhope Road, Victoria Park and Old Portsmouth are worryingly high. It predicts that pollution in Southsea and Milton is relatively less severe. Annoyingly, there are few predictions for the Albert Road area (which, to be fair, is not the focus of this report). Pollution is particularly bad at busy junctions along Kingston Road and Commercial Road.
The map may give us ideas for additional air quality monitoring locations for both the council and for citizen science projects.
Although the data is a little dated, it does show the amount of work needed to make Portsmouth’s air safe to breathe. The recent grant of £450,000 from the Clean Air Fund is welcome but I do wonder what it would cost to actually solve the pollution crisis?
The next blog post will probably be on the impact of the city centre road scheme, and specifically which locations are affected.
PS. Please sign the petition!