Voices of Science

Ah well, it was, that leads back. When I was in Bowerchalke first, way back in the 1950s, I noticed that in the summer the air was unusually hazy whenever it blew from Europe. And I got so interested I got – when I was over in America and visiting the National Centre for Atmospheric Research at Boulder, I got the scientists there interested and they gave me what was called a sun photometer, which is an instrument you can measure the haziness by looking at how much sunlight’s absorbed by it. And my family and myself kept a record of the haziness all of the time. And then I kept on wondering where the hell is this haze coming from, what’s the source? And you couldn’t just say, ‘Well it’s coming with the easterly wind off Europe, so it must be industrial pollution,’ because it might have been coming out of the sea or out of the land or anything like that. And I thought well what compound could there be that comes from big cities, where people are, that is not anywhere found in nature? And it didn’t take me long to think CFCs. They’re in every refrigerator, and at that time people were using them in spray cans and they were being poured into the air all the time, albeit in very low levels. Now it would mean detecting them at the parts per trillion level; could I do this? Yes, duck soup with the electron capture detector. So I started measuring haze and the presence of CFC-11, which was the easy one to detect, simultaneously. And soon found a strong correlation, whenever the haze comes, then the CFCs rose steeply in the air to a much higher concentration, about three times greater than in the clear air.