Criticism in the US of the oil industry’s obfuscation over the climate crisis is intensifying after internal documents showed companies attempted to distance themselves from agreed climate goals.

Where did this come from?

Dyson said it started having internal conversations in 2016 about developing some kind of “purification on the move” technology, based on its existing air purification technology.

During initial trials in the smoggy city of Beijing the company struck upon the idea of integrating noise-canceling headphones.

Doing this also meant the company was able to design the headset so the air filters could be placed in the earcups, minimising some of the unusual bulkiness in previous prototypes.

In its final form the Zone uses a visor to channel “a continuous stream of purified air to your nose and mouth, without touching your face” according to Dyson, which will help address stuffiness.

A separate attachment is also going to be offered that could allow people to turn the headphones into a sealed, full-contact mask.

The two-stage purification system is “capable of filtering city fumes and pollutants” and uses a miniaturised version of Dyson’s existing air purification technology.

Each filter would need to be replaced after about a year and are capable of filtering out 99% of particle pollution, according to the company – depending on how much use the headphones get.

It follows Public Health England warning that air pollution is the single biggest environmental threat to health in the UK, “with between 28,000 and 36,000 deaths a year attributed to long-term exposure”.

Some reviewers have said despite the music and the noise-cancelling technology, the whirring of the air purification units is still audible. Dyson says more information will be forthcoming nearer to launch.

But with the period of national mourning ending after the funeral, when Truss will fly to New York to attend the UN general assembly, and with MPs returning to Westminster on Wednesday or Thursday, the transition back to normal politics will be sudden and potentially bruising for a prime minister who had only been in office for two days before the Queen’s death.

On Saturday night, leading UK business organisations were renewing pressure on ministers for “absolute clarity” on what help government would offer them with their energy bills and warning of dire consequences if they continued to be left in limbo over the level of support in the medium term.