Analysis: behind the news
Stephen Peckham is well-known in Canterbury for his work on Air Quality. He also has a global reputation for the work he does as Director of the Centre for Health Services Studies at the University of Kent. One of the roles of the Centre is to examine the relationship between health and air pollution. So how is air quality changing under Lockdown? Where do we go from here? And what are the links between lung damage caused by pollution and susceptibility to Covid? Professor Peckham talks to Canterbury News Editor Neasa MacErlean. This is the second in a series of in-depth issues focusing on one subject, following on from our interview with Rosie Duffield MP.
Many people are thinking that air quality in the district must have improved since March 23 when Lockdown started. Is that so?
There are three different pollutants to talk about — NO2, PMs and low level Ozone. In Canterbury we have seen a quite significant drop in NO2 levels. We seem to be tracking along levels that are below what we used to find. Regarding PM2.5s, we haven’t seen major drop-offs in levels. The PM levels appear to be similar. And as for Ozone, the levels haven’t changed.
How has this affected people with asthma and other respiratory conditions? I understand that, in ‘normal’ UK conditions, one in 11 children and one in 12 adults receive treatment for asthma.
Across the UK there have been fewer people admitted for consultations on asthma. GPs are handling fewer consultations, particularly for childhood asthma. But on the child asthma cases, I suspect that might be related to air quality — rather than people staying away from the healthcare system — because parents do tend to bring children in with asthma problems. And given that some of the peak levels of pollution have dropped when children are walking [along busy roads to school] that might be one reason why asthma levels have dropped.
Regarding other conditions, there is interesting anecdotal evidence. One GP I know said that stroke and myocardial infarction levels of admission are down. That might not — or might be — due to air quality. We don’t know.
Tell us more about NO2 please.
On Military Road where NO2 levels are monitored by the City Council, we are roughly at half of the daily levels of 60-70 [millionths] that we were seeing in February, before Lockdown. It’s not as dramatic as you might think. On St Stephen’s Road [where the University has a monitor in place] average levels are also well below what they used to be. There used to be spikes of 160 there but now it rarely goes above 60/70, and the average is well below 40. However, in the last two weeks of April NO2 levels in Military Road seem to be gradually increasing again. In London the differences, before and after Lockdown, are much more significant. On Oxford Street, the drop has been of nearly 50 per cent. You would expect to see major drops in big urban areas.
Changes in PM levels are far less obvious, probably because we may be seeing higher household use of gas compensating for the levels that would have been created by traffic.
And why isn’t Ozone falling?
This is important for respiratory problems. A factor in that is that as you reduce NO2 level, O3 levels tend to go up…..You have to reduce NO2 quite substantially to stop releasing the spare Oxygen. We have also experienced a period of sunny weather and the interaction of sunlight on oxygen creates low level Ozone.
What will happen to Air Quality as we come out of Lockdown?
During the Lockdown, car use has dropped. Outside London it has fallen from 90 per cent of total to the mid 30s. Public transport use has also dropped by some 60 per cent.
So there are a couple of points relating to what happens after Lockdown. First, the main hope is that some people’s travelling may have switched to more active modes — cycling and walking, for instance — and they might stick to it. But we ought to be a little circumspect. People may be fearful of using public transport, so they might use cars more. So, perversely, we might see a drop in public transport use — outside of London. (In London it is more likely that bus and train use will pick up.)
Also, if people suddenly have the freedom to do things they haven’t been able to do they might use cars more to visit places and people that we have not been able to for several months. If it’s gradual, then it may not happen so much.
What steps could we take to stop car use increasing post-Lockdown?
We need to think about how we make sure it’s safe for people to go on public transport. Testing is a vital part of that. If we don’t test we are really going to cause ourselves problems.
Bus drivers in London and Birmingham have been more at risk. [As of 23 April, the Standard was reporting that 23 bus workers had died of Covid19.] Protection for them must be a must. But you can’t partition every seat so the only way is testing and contract tracing. It has got to be done: it’s the only way we can ensure safety.
What action should we be taking as a result of lessons learnt from Covid?
Defra [The Department for Environment, Food and Rural Affairs] has called for evidence around the impact of Covid19 on air pollution. If the data does show that there are significant drops in some health problems then we need to act on that. A good measure would be if we see lower uses of asthma medication during Lockdown. Another measure would be the number of admissions for COPD [Chronic Obstructive Pulmonary Disease], respiratory disease, stroke and cardiovascular problems. If there are reductions related to Air Quality that puts extra pressure on the government to publish better targets for government.
A particular area is PM2.5s. At the moment there are no government targets on that — so local authorities such as Canterbury City Council do not have to measure them or manage them. The government’s Clean Air Quality Strategy (2019) said it would be good to set targets for PM2.5s. But there are no targets in the Environmental Bill currently being debated in Parliament.
It’s the same with low level Ozone. Local authorities are not required to consider it. That is a particular issue here. Even though Canterbury breaches the Ozone guidelines set by the UK Government every year, the local authority is not required to take any action. Canterbury is particularly susceptible to three factors which increase Ozone levels — traffic levels, sunshine levels and being in a geographical bowl.
Is there a potential link between Covid19 cases and the pollution that comes from high traffic levels and higher industrial output? For instance, Italy’s industrialised Milan-Veneto region has been famous for its poor Air Quality and it has suffered more from coronavirus than anywhere else in mainland Europe.
There has been one large-scale study of Italy, Spain, France and Germany. That shows there is a higher level of death in areas where pollution is higher. But there are two key problems with making that link. First, we know that pollution is associated with respiratory and cardiovascular problems, both of which are high predictors of Covid19 disease. Thus it is not the level of pollution that is directly linked to COVID-19 deaths but the already greater number of people with COPD [Chronic Obstructive Pulmonary Disease] and cardiovascular disease as a result of pollution placing people more at risk. Secondly, pollution occurs in urban areas where people are close together — so you could expect a higher level of infection in those areas because of that population density. So I don’t think we know enough about what the link might be.