The British public’s support for fracking has fallen sharply in the last year and is now at the lowest level ever, according to a long-running poll published as the industry gears up to begin drilling.

New polling by YouGov for the University of Nottingham, which has been tracking attitudes towards shale gas extraction for more than four years, shows support for fracking in the UK is now at 37.3%, down from 46.5% a year ago and 58% in the summer of 2013.

Opposition has hardened too, up at 41% from 36.1% one year ago, meaning more people oppose than support the controversial technology for the first time.

The survey of 4,500 people took place just before the decision last week by communities secretary, Sajid Javid, to allow fracking in Lancashire by overturning the county council’s rejection of Cuadrilla’s fracking application. Rival company iGas is awaiting a decision next month on its bid to drill shale gas wells near Doncaster.

“The sharp downturn in support for the extraction and use of shale gas in the UK over the last 12 months is hugely significant, as is the fact that for the first time since we began running the survey in March 2012 more people are against shale gas extraction than in favour,” said Prof Sarah O’Hara at the university’s school of geography.

The detail in the latest round of polling does not make for encouraging reading for the industry, which has tried to position shale gas as a way to secure energy supplies and create economic growth.

The survey found the number of people who believe shale gas is a clean energy source at its lowest level in the poll’s history, and those associating it with higher greenhouse gas emissions at their highest level yet. The proportion of people who associate fracking with water contamination has also reached new highs.

While most respondents still felt exploiting the gas would bring economic benefits to the UK, those people are declining in number. The poll was conducted a month after Theresa May promised cash payments to households near shale sites.

“It is clear that people are not only concerned about possible impact on their immediate environment, something that dominated early debates around shale gas but importantly are beginning to think more broadly about the implications for greenhouse gas emissions and future climate change,” said O’Hara.

She found that shale gas was the least acceptable energy source in the UK from a range of renewable, fossil and nuclear fuels. The decline in public support for fracking since July 2013 appears to be linked to the protests in August 2013 against shale company Cuadrilla’s plans to drill a well at Balcombe, in West Sussex.

The poll’s findings are similar to the government’s own public attitudes tracker, last updated in July, which found 31% of people opposed to fracking compared to 21% supporting it.

Ken Cronin, chief executive of Ukoog, the trade body that represents the shale industry, said: “We have long believed that once people get to see how little impact shale gas exploration has on the environment and communities then attitudes will swing strongly in favour.”

Josh Fox, an anti-fracking campaigner and film-maker, told the Guardian that despite expert bodies such as Public Health England saying shale gas could be extracted safely in the UK, he believed fracking would cause a “health crisis” if it took off in the UK because of water contamination and local air pollution issues.

“If the UK decides to go down the road America has gone down, it will mean we’re starting the fracking wars all over again,” said Fox, speaking from London during a tour of the UK to promote his new climate change documentary.