Growing up in the Leeds of the 1960s, the air was very polluted with fumes from industry and the coal fires that every house had to use. Several times each winter, when atmospheric conditions caused it, there was smog. This was caused by tiny droplets of water enclosing particles of soot and other particulates and floating in the atmosphere. The resultant smog was very harmful to health - especially for those with breathing problems - and very difficult for transport because visibility was often reduced to a few yards.

I remember cycling home from school on many occasions in smog. The first precaution was to tie a handkerchief around the nose and mouth before setting off, then to choose a route on main roads to make it easier to avoid getting lost in the poor visibility and dim street lighting of those days.

Living in north Leeds, I usually chose to cycle on Street Lane, quite a wide major road which took me most of the way home. Very often, cycling quite slowly to be safely with my range of visibility to avoid stationary vehicles and other obstacles, I would become aware of a long line of cars behind me. It wasn't that they couldn't overtake, it was that they found it safer to follow me - expecting that I knew where I was going - than to pass me and have to peer into the dark gloom themselves.

Once home, I would remove the handkerchief and put it into the wash as the parts covering my nose and mouth were black where I had been breathing through them. I had to wash my face as well - all round my eyes was black where the smog had condensed into soot. The good old days?

Fortunately, Clean Air Acts were passed and, as the atmosphere gradually became cleaner, smog became a thing of the past.