The significantly cleaner air being breathed in the UK in recent months is likely to deteriorate over the coming week as the lockdown eases on Monday, triggering a surge in road traffic.
Many other countries which have eased restrictions enforced at the height of the coronavirus pandemic have since seen numbers of vehicles on the roads soar to record levels.
As many shops and workplaces open for the first time since 23 March on Monday, pollution levels are expected to climb and the number of road accidents is likely to rise.
In China, as restrictions have eased and travel and industry resumed, air pollution is now overtaking the levels prior to the pandemic.
In Wuhan, where the outbreak began, car use is now hit levels higher than before the pandemic, and the same is true of Stockholm in Sweden.
As lockdown measures have eased, authorities in cities around the world