Measuring pollution in Heath Street

• YOUR report on air pollution in Hampstead is interesting (ECO 2022: Toxic air is a big threat, January 6), but I hope you can take the “story” further and clear up a couple of points which remain perplexing.

We read first that measurement of nitrogen dioxide over a six-year period “has found that the amount of air pollution has dipped”.

The report refers to “the legal limit” and links that to World Health Organisation air quality levels targeted for 2030.

The WHO has very recently lost brownie points over its analysis of the current virus epidemic so we need to be generous to accept what it says must be attained vis-à-vis air pollution.

And did the United Kingdom introduce the WHO standards and targets with or without parliamentary debate into UK law?

Later in the report we read that “traffic levels… in Hampstead have returned to pre-pandemic levels…”, which seems to mean that there is now, again, more motor traffic (many of which cars are now electrically-driven).

So traffic has recently increased but amount of air pollution has dipped. Do we therefore have to enhance levels of panic when other reports remind us that anxieties and mental health problems have increased?

Finally those who look at BBC weather forecast reports might have noticed that every day there is a small green symbol at the foot – and that seems to mean that pollution is either already low, or expected to be low.

If that is what the BBC (from the Met office) is telling us, how does that information square with what the volunteer projects reveal? I have asked the BBC what this symbol refers to but have not had any reply.

There is more for us to be told about all this!

MALLORY WOBER, NW3