Mea Culpa: clear the air about tiny particles of pollution

We got into trouble in our report of air pollution affecting British schools. The report was about the World Health Organisation’s guidelines for “fine particulate matter”, that is, particles smaller than 2.5 micrometres in diameter, for which the conventional shorthand is “PM2.5”.

We tried to explain this as “tiny particles more than 100 times thinner than human hair”, which was confusing, as Roger Thetford pointed out. Human hair is long and thin, whereas particles are roughly round. The average human hair is 50 micrometres in diameter, so the factor is more like 20 than 100. And I think you can say something is 100 times thicker than something else, but going the other way is harder for the brain to compute, especially when using the phrase “more than” when the sense is “smaller than”. Altogether, then, I think we could have said something like “tiny particles with a diameter one twentieth that of human hair”.

We then got into further difficulty by saying that the World Health Organisation recommended limit for the amount of PM2.5 in the air is “10ug/m³”. Roger objected to the use of ug as the symbol for micrograms, because it should be μg, with the initial letter the Greek mu. My objection is simpler: that I don’t know what μg means, whereas microgram, meaning one millionth of a gram, is easier to understand. I think we should have said “10 micrograms per cubic metre”.

Ahead of the change: Roger Thetford also pointed out a glitch in our report of the inquiry into the Manchester Arena bombing. We said: “Months of hearings have laid out harrowing details of how Salman Abedi was able to lay in wait during an Ariana Grande concert.” Language changes, and “lay” is commonly used in this way, especially by young people in conversation, but conventional English is still “lie”.

Resist this invasion: We used the vogue phrase “push back” a couple of times last week. Cole Davis thinks we should stick to familiar English and I tend to agree with him. In a report of viewer complaints about Dan Wootton’s anti-lockdown monologue on the opening day of the GB News channel, we said Mr Wootton “encouraged viewers to push back against ‘doomsday scientists’”. I think “resist” or “object to” is better than “push back against”.

And in our report of Vladimir Putin’s news conference after his meeting with Joe Biden, we said: “Mr Putin pushed back at the notion that the Russian government was behind the ransomware attack in May on the Colonial Pipeline.” That is even worse, because if you are going to push back, you push back against something, not “at” it. But “Mr Putin rejected the notion” was all we needed.

Offgoing: My campaign against “ongoing” is still going badly. We described a development in the rivalry between two golfers as “the latest episode in the ongoing saga” – well, it wouldn’t be the latest episode in a saga that had come to an end some time ago, would it?