A shale gas company's lorries, police vehicles and protesters' wood fire has been reported to drive up air pollution levels near a gas well in the north of England.
Operations at the Kirby Misperton Well in North Yorkshire have been delayed after the operator, Third Energy ran into financial problems, but the project's local pollution impact is revealed by government-backed research.
Alastair Lewis, a professor of atmospheric chemistry at the University of York, said his air quality monitoring project found a group of pollutants had increased in the vicinity of the site to levels rather than a rural area rather than seen in a city.
The cause was lorries supplying the well, opposition by campaigners and the resulting police operation.
"The biggest, most visible detectable impacts on the surface are on the nitrogen oxides (NOx), from the use of compressors, generators and truck movements," Lewis said.
"And, strangely, in the case of Kirby Misperton, from policing, from [police] vehicles and protest camps It's a slightly unusual situation in that activity of protesting itself is a large source of pollution. "
He said protesters such as slow walking in front of lorries supplying the site would have driven up NOx levels, and police vehicles had been pollutants of a "significant" source.
North Yorkshire police spent more than £ 600m on policing protests at the site of the fall and the winter of 2017-18.
Lewis said monitoring had also been detected particulate pollution.
He said the overall air quality impact of the site was a single supermarket.
"It kind of shifted to a semi-rural location in a chemical environment, which has seen more similar to a city suburban environment for NOx," Lewis said, but he added that the levels did not break the regulatory limits. The full research will be published later.
According to an earlier government report, according to the shale gas industry scales up to a national level with 400 wells, NOx levels will increase by up to 4%.