Paris air dirty – 100 years on

Using data taken by a long-forgotten scientist who set up an experiment on top of the Eiffel Tower in the 1890s, it was found that the air in Paris today is just as dirty as it was 110 years ago, at a time when the city was recklessly burning coal, the dirtiest of fossil fuels.

The obscure scientist was Benjamin Chauveau, who carried out tests atop of the just-completed tower to assess the conductivity of atmospheric electricity.

The potential atmospheric electrical field varies according to
altitude, time of day and the season.  The phenomenon is so well known that values for these can be calculated, allowing researchers to determine the remaining variable: particle pollution such as dust from industrial sources or ash and soot from the burning of carbon fuels.

Working backwards

Poring over Chauveau’s carefully recorded data, British meteorologist Giles Harrison of the University of Reading and Karen Aplin of the Rutherford Appleton Laboratory realised they could work backwards to get a good idea about how bad pollution was in Paris during the Naughty Nineties.

Petrol and diesel have replaced coal as the new pollutants

Writing in December’s issue of a specialist journal, Atmospheric Environment, they figure that the concentration of surface smoke pollution in mornings in the French capital in the 1890s was between 30 and 90 microgrammes per cubic metre of air.

Coal burning has long been banned in Paris to help clean up the air in a city that sits in a basin and is notoriously vulnerable to atmospheric inversions. But the figures show that the particulates spewed up by coal have been replaced by those from burning petrol and diesel.

The website of Airparif, the agency that monitors airquality in
Paris, says that the daily average level of fine particulates in
2001 was 70 microgrammes per cubic metre of air. The goal is to bring this down to 50 in 2005 by encouraging cleaner vehicles and greater use of public transport.