April 2, 2014

expert reaction to high levels of air pollution in England

Defra has issued warnings about high levels of air pollution in the southern half of England which are a combination of local and European emissions and dust from the Sahara.

Dr Helen Dacre, a meteorologist at the University of Reading, said:

“High air pollution levels can cause unpleasant and dangerous effects on health, both long and short term. Toxic gases, such as nitrogen dioxide and ozone, as well as fine dust particles in the air blown in from the Sahara and from burning fossil fuels, all contribute to cause problems for people with heart, lung and breathing problems, such as asthma.

“The problem is likely to be particularly bad today because weather conditions have conspired to create a ‘perfect storm’ for air pollution. British car drivers and heavy industry create bad enough smog on their own, but the weather is also importing pollution from the industrialised urban parts of Europe, which is blowing across Britain. Saharan dust gets blown over to Britain several times a year – the current episode has been whipped up by a large wind storm in North Africa. This has all combined to create high concentrations of pollutants in the air.

“Forecasting pollution is particularly difficult and complicated. It combines the uncertainties of a five-day weather forecast, with predictions about emission levels, and models of how pollutants combine chemically or interact with sunlight to create secondary pollutants. At Reading, we’re currently engaged in research to evaluate the accuracy of the Met Office’s new five-day pollution forecasts. We hope that by comparing forecasts to what actually happens in terms of pollution, we can identify ways to improve the forecast, making it more accurate and useful for people who rely on it to plan their day-to-day lives.

“The University of Reading is also conducting research to see how climate models, which show how climate patterns will shift in the future, could be used to predict if pollution will get better or worse in the future. By examining past relationships between weather patterns and pollution, we can use this information to determine how shifting weather patterns are likely to change the UK’s pollution levels in the future.”

Jo Barnes, Research Fellow at the Air Quality Management Resource Centre, University of the West of England, said:

“While the high levels of air pollution that we are seeing this week across England and Wales are a result of a combination of short-term meteorological factors and continental and Saharan sources, it is important to recognise that this is simply adding to and exacerbating existing long-term poor air quality experienced in many of our towns and cities much of the rest of the time.

“There are already more than 60% of UK local authorities with Air Quality Management Areas declared for exceedances of air quality objectives for nitrogen dioxide (NO­2) and particulate matter (PM10), primarily for traffic-related sources.  In February 2014 the European Commission launched legal proceedings against the UK for its failure to cut excessive levels of NO2.  Technological solutions (e.g. Euro standard vehicles) have not delivered the expected reductions in pollutant emissions and resulting concentrations and behavioural changes (e.g. driving less) are difficult to bring about without greater public awareness and education about the effects of individual’s actions.

“It is therefore good to see that this week’s extreme pollution has made it onto the media and public consciousness, but I hope that it doesn’t give the false impression that once the rains come everything will be fine!”

Prof Alastair Lewis, Professor of Atmospheric Chemistry at NERC’s National Centre for Atmospheric Science, said:

“The current conditions highlight the rather limited room for manoeuvre that exists for controlling severe UK pollution events. 

“The worst air quality days in Britain often involve the import of pollution from continental Europe on easterly winds – from traffic, power stations, agriculture, industry and so on – and this current event is compounded by natural dust as well. 

“Since cumulative exposure to pollution occurs year-round, it reinforces how important it is that we do all we can to improve air quality under more ‘normal’ weather conditions, when our fate is more in our own hands.”

Prof Ellie Highwood, Professor of Climate Physics at the University of Reading, said:

“The current pollution episode is the result of tiny particulates (atmospheric aerosols) that come from traffic, fossil fuel burning, agricultural practices and, more unusually, dust from the Sahara.  The high pressure system with light winds at the surface and little rain allow particles produced locally to build up in the atmosphere.  Larger scale weather patterns bring air from continental Europe and further afield that also contains aerosols.

“This particulate pollution is responsible for hazy, milky skies since the particles scatter sunlight out of its direct path from the sun to us.  Because of their size, the light reflected from these particles appears white as they reflect the different colours of visible light equally.  However, the extra bouncing around in the atmosphere also leads to more interactions with the molecules of atmospheric gases, and these tend to scatter blue light more than red.  So if we are looking towards the sun, say at sunrise or sunset, we will tend to see a more red sunset or sunrise than if the atmosphere was clean.

“PM2.5 is monitored because the particles are small enough to pass into the lungs and irritate them.  Some of the things that make up these particles can also pass into the blood stream.  When PM2.5 levels are high, people with existing lung or heart conditions should take care, and even healthy people doing strenuous physical activity outside (e.g. cyclists) might notice a sore throat or cough.”

Prof Ian Colbeck, Professor of Environmental Science at the University of Essex, said:

“This pollution episode comes just a week after the WHO estimated that 7 million premature deaths annually are linked to air pollution.  It is now the biggest single environmental health risk.  In the past, respiratory diseases (such as chronic obstructive pulmonary disease) were thought to be the main killers but it now emerges that heart disease and strokes account for up to 80% of deaths.”

Prof Frank Kelly, Professor of Environmental Health, King’s College London, said:

“The UK’s ongoing air quality problems are highlighted this week by the very high pollution levels which have made air pollution visible to everyone in the southern parts of England.  This air pollution episode follows quickly on the heels of the previous episode which affected most of Europe and led to restricted car use and free public transport in Brussels and Paris.

“Periods of very high pollution in London arise usually because the city’s normal pollution emissions are increased further by polluted air arriving on light winds from neighbouring areas such as northern Europe.  However, whether home produced or arriving from the continent, the tiny particles we take into our bodies with each breath cause immediate problems for some individuals such as those with asthma and contribute to longer term problems for most of us in the form of heart disease and stroke. For those who are sensitive to air pollution its important they are provided with accurate forecasts of when air quality will deteriorate so they can plan their activities to reduce exposure, perhaps by taking different routes to work or school or avoiding strenuous exercise on those days.  Even those who do not feel any particular sensitivity to air pollution can benefit from such avoidance techniques but they will have to wait several decades to see the benefit.”