from Sunday Herald New Era magazine, 19 May 2013
by Rob Edwards and Colm Currie
We teamed up with Dr Sean Semple, a leading air pollution expert from the University of Aberdeen, to take portable, state-of-the-art monitors to record concentrations of tiny particles in the air during a journey through Scotland last Thursday and Friday. The results were eye-opening.
The problem with the official monitoring network is that it is based on static samplers, which simply measure pollution at a particular place. The portable monitors enable scientists for the first time to get a more accurate estimate of the pollution to which people on the move are actually exposed.
We started our journey at Aberdeen University. There were a couple of small pollution spikes in a taxi on the way to the railway station, but the pollution didn’t get serious until we arrived at the station, where levels of tiny particles on a platform rose up to twice as high as the daily limit recommended by the World Health Organisation (WHO).
After a few smaller spikes during the train ride to Edinburgh, the next big dose of particulate pollution was at Waverley station. The next day returning to Waverley saw another peak, confirming the Sunday Herald’s revelations in December about high levels of pollution at the station.
Pollution was also noticeable at Queen Street station, but when we joined the subway at Buchanan Street it rocketed. For the best part of an hour, as we traveled to Hillhead, then to Cessnock, and then to St Enoch, the mass of particles in the air was much higher than elsewhere, reaching eight times the WHO daily limit.
When the actual number of particles was counted, the picture becomes more disturbing. Levels rose sharply from less than 10 million particles per cubic metre of air outside the subway up to 80 million particles inside the subway.
Most of the pollution in the subway was probably tiny fragments of iron from the wheels of the train grinding against the rails. We encountered another high pollution peak at Central Station, and then lower but significant concentrations walking around the city centre (see graphs below).
Semple, a senior lecturer in environmental medicine and a founder of the Scottish Centre for Indoor Air, estimated that a person riding for 45 minutes on the subway could inhale a minimum of 60 million tiny particles. But he pointed out that if the particles were iron they could be relatively less harmful to health than the diesel fumes found in railway stations and elsewhere.
The subway pollution needed further investigation, he cautioned. Diesel particles, however, were known to be harmful to health “and exposures to high levels can be particularly problematic for people with heart or respiratory conditions,” he said.
Pollution in indoor and semi-indoor spaces like cars, trains, buses and railway stations can be much higher than outdoors, he argued, yet we know far less about it. New Era’s survey gave “a snapshot of journeys across Scotland and show how our exposure can vary markedly in the space of a few metres,” he said.
He added: “Instruments allowing us to understand much more about how we are exposed to air pollution are becoming cheaper and simpler to use and should extend our understanding of the risks from air pollution to our health.”
Dr Richard Dixon, director of Friends of the Earth Scotland, described the levels found on the subway as “alarming”. He called on Strathclyde Partnership for Transport (SPT) to take the results very seriously.
He said: “This problem urgently needs further investigation and confirmation of these results would require decisive action to reduce pollution.”
Pollution on diesel trains was regarded as “low risk” because the exhaust vents were at roof level. There were initiatives at Queen Street to cut the time engines idled and to increase the use of low-polluting fuel.
“We believe we are taking reasonable measures to reduce emissions,” said a Scotrail spokeswoman. “The increasing electrification of the rail network – most recently between Glasgow and Paisley Canal - will also help to improve air quality over the longer term.”
Network Rail, which owns Waverley and Central stations, said it was committed to cutting pollution “where possible”. It too limited train idling time, and restricted vehicle access to stations.
“Further planned electrification of the network will also reduce the number of diesel trains using our busiest stations,” said a company spokesman. “We would also be happy to review the data collected.”
Comments made by Strathclyde Parnership for Transport (SPT) after this article had gone to press are included in a related story here.
The results of New Era's monitoring in Glasgow, Edinburgh and Aberdeen
The black lines in the above three graphs show particles detected by the Dylos DC1700 air quality monitor at the times and places shown. The turquoise line in the last graph shows particles measured by the TSI Sidepak Personal Aerosol Monitor AM510. The red dotted line on the last two graphs shows the World Health Organisation's recommended maximum exposure to PM2.5 particles, averaged over 24 hours. The monitoring on 9 May 2013 was carried out by Rob Edwards, and the monitoring on 10 May 2013 was carried out by Colm Currie. All the results were downloaded, analysed and graphically realised by Dr Sean Semple, from the University of Aberdeen.