This makes very little sense. Air pollution is too local to be meaningful at a country level. Is air quality in London the same as it would be in Cornwall a few hours drive away?

Air quality has increased greatly over time in developed countries so labelling present situation a "catastrophe" seems rather too late. London has been continuously improving in terms of just particulates for over a century, and hugely so:

https://ourworldindata.org/grapher/air-pollution-london-vs-d...

The UK on other measures:

https://ourworldindata.org/grapher/air-pollutant-emissions

and that still does not take into account lots of other improvements, including things that have been banned altogether (leaded petrol).