If you'd seen the gorgeous dawn sky over London this morning, you might well have felt blessed that various administrations have cleaned up the air we breathe.

One way or another, they've managed to get so many poisons out of the air - no simple task when almost nine million people are breathing the stuff in at a minimum of a dozen inhalations a minute, and 30 for babes, and 24 for resting dogs, of which the metropolis also has a vast number.

Image of part of  a Sailing to Purgatory webpage to illustrate the article.
Cool ... Perfectly cool, man, the experts tell us. Let's hope they're right. Photo by William Hook on Unsplash and many thanks to photographer William and the Unsplash organisation

I was thinking gratefully of the good work as I cycled back from the gym this morning.

The gym is slap bang beside the Kingston bypass, a stretch of highway that is chocker with huge lorries and ordinary lorries and vans and cars and motorbikes of the noisiest breed.

Checking pollution

Official figures show that the amount of traffic on that highway is H U G E !

And yet, in spite of that, check pollution of the air at the gym and the online monitor shows that beside that frantically busy stretch of the A3 it's 'Low'.

Since sailing round the world on my own, the moon rates as a friend. She was beautiful this morning in that crisp air. But as I admired her, I became aware of the airliner trails filling the sky over London. I counted more than a dozen.

Is that stuff coming from airliners safe? Look at the web and you'll find a zillion reassurances. Basically, they reckon, it's just hot air coming from hot engines and being frozen up there by the very cold air. Perfectly safe.

Should we be reassured?

The way the amazing airline world is growing, a dozen trails this morning are likely soon to be three dozen. Should we be reassured?

The Aviation Benefits website tells us that the world's airlines carry over three billion passengers a year and 50 million tonnes of freight.

'Providing these services generates 9.9 million direct jobs within the air transport industry and contributes $664.4 billion to global GDP.'

What sort of funds could such a huge and rapidly growing industry afford to spend on providing desired answers.

What can you say about anything in life that dominates with such importance? We might as well hope for the best for our vital element because it is unlikely we will ever know. Well, not until it's too late, should the reassurances be no more than that.

Thanks very much for visiting the blogs for my adventure book, Sailing to Purgatory.