QUEEN VICTORIA breathed London air that was 100 times smokier than today鈥檚, according to atmospheric records. But the large smoke particles of her era have simply been replaced by smaller ones, which are also damaging to health.
Giles Harrison of the University of Reading, UK, used samples of airborne smoke particles and measurements of the air鈥檚 electrical conductivity taken in London between 1898 and 1979 to deduce the particle load in the air over that time. 鈥淎ir is more conductive when it is clean and less conductive when it is polluted,鈥� he says.
Harrison found that 19th-century London air contained around 100 times more smoke particles than 1970s air, but the atmospheric electricity measurements remained constant. He thinks he knows what is to blame. 鈥淭he pollution hasn鈥檛 gone, it has just changed. Smoke sources have been reduced, but have been replaced by less visible, ultra-fine particles,鈥� he says. His work is in press in the journal Atmospheric Environment.
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Cyclists who wear masks in an attempt to filter the air they breathe should take note. David Muir of the Environmental Quality Unit of Bristol city council, UK, doubts they do much good. 鈥淭hey are unlikely to take out much, if any, of the fine fractions,鈥� he says.
