In August 1921, John Switzer Owens had a UK holiday. He went to Holme, Norfolk, and took his latest invention with him. Each day he took his device to the beach to sample the air. He also flung thistledown into the sky and noted its passage over the sand to understand where the wind came from.
When the wind came from Germany’s industrial Ruhr, it became hazy and particle pollution soared. Later he found that air pollution from the Midlands reached the south coast and pollution from London reached Devon and Wales. In spring 1922, Owens also discovered widespread air pollution enveloping all of south-east England at the same time but could not find a source.
For the next 50 years air pollution scientists focused on local coal smoke, forgetting evidence that air pollution could travel long distances.
If Owens’ device had been perfected, we might have taken early steps to control UK coal burning to prevent Scandinavia’s acid rain crisis of the 1970s and 1980s, and action to avoid the air pollution that still covers western Europe each spring and summer.