Most news outlets ran coverage, suggesting that people shouldn't exercise outdoors too much
Of course, London wasn't alone in this. But it didn't stop some schools taking, erm, extra care...
Dear Boris remained completely unphased, we can assume he isn't one of the millions of asthma sufferers then
But pollution did hit max levels on government scales
Maps like this prove useful for people wanting to avoid those carcinogens, although poor air quality could be a form of altitude training, joked runners
The Evening Standard said it was a threat to people's London Marathon training plans. Officials refused to go down the route taken in Paris and limit the number of cars which could be driven each day.
The best part, at least for instagramers, was without doubt the photo ops. And there were a lot: