The claim: Air pollution in London last week was worse than it was in Beijing.
Reality Check verdict: Some one-off readings were higher in London last week, but this was an unrepresentative snapshot and Beijing is generally far worse.
Ruth Cadbury is the Labour MP for Brentford and Isleworth, a part of London that has seen unusually high levels of air pollution recently.
Last week saw the highest level recorded in the capital since April 2011.
The spike was attributed to cold, calm and settled weather, meaning winds were not dispersing local pollutants.
Different countries measure air pollution in different ways.
The UK government uses a one (lowest) to 10 (highest) scale.
Last week's levels in London were a 10.
Another measure is the Air Quality Index (AQI).
Last Monday, according to this measure, some parts of London showed particulate levels a bit higher than in Beijing.
But this was just a snapshot and not the case for most of the week.
On Wednesday afternoon, the overall AQI level in Beijing was about three times higher than in London, and recordings were even higher on the Chinese city's industrial outskirts.
The World Health Organization gathers average particulate levels from cities around the world.
They suggest that Beijing's levels are about five times worse than London's.
The cities with the dirtiest air are Zabol in Iran and Onitsha in Nigeria.
In the UK, overall emissions of all types of air pollution have fallen dramatically since 1970.
Pollution in Beijing is much worse than in London - or in Stockholm, where the same claim was made this week.
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DreamHost had argued the DoJ's warrant would have revealed 1.3 million IP addresses.
The DoJ has now narrowed the scope of its demand.
Disruptj20.org was set up to help arrange a protest at President Trump's inauguration.
"The government has no interest in records relating to the 1.3 million IP addresses that are mentioned in DreamHost's numerous press releases and opposition briefs," prosecutors said in the new request.
They were focused on the use of the website to plan and carry out a criminal act - a "riot" - not the "lawful activities of peaceful protesters", they said.
The warrant does not now require certain access and error logs, which, DreamHost says, means visitors' IP addresses are "largely safe".
"We see this as a huge win for internet privacy, and we absolutely appreciate the DoJ's willingness to look at and reconsider both the scope and the depth of their original request for records," DreamHost said in a blog post.
However, it still plans to challenge the DoJ on other aspects of its request.
Prosecutors signed the original warrant to DreamHost in July, arguing that disruptj20.org had been used to organise "violent" protests in Washington DC.
DreamHost and privacy advocates argued that amounted to a "digital dragnet".
In its updated warrant, the DoJ said that the full scope of the original request - criticised by DreamHost in its public statements - had been "unknown to the government and the court at the time that the warrant was issued".
Data still required by the amended warrant includes files and databases stored by DreamHost.
More than 200 people have been charged in relation to rioting at the inauguration.
On 22 January, recordings of particulate air pollution were higher in London than in Beijing.
[NEXT_CONCEPT]
Visitors to an anti-Trump website will probably not have their internet protocol addresses turned over to the Department of Justice, after a legal standoff with a US web company.