The government cannot achieve the air quality improvements advised by medical experts, so has set its targets lower for the next 10 years, the environment secretary has admitted as she unveiled a new environmental plan. Thérèse Coffey said on Tuesday: “We have cleaner air. I want it to be even cleaner. Now, I would have loved to have made our target to achieve 10 micrograms [of fine particulate matter, known as PM2.5, per cubic metre of air] by 2030, not 2040. Many parts of the country already enjoy this, but the evidence shows us that with the best will in the world we cannot achieve that everywhere by the end of the decade, particularly in London.” But air pollution experts pointed to research by King’s College London and Imperial College London that has shown the government could achieve the more stringent targets, which are supported by the public in polls, if it took stronger action on the sources of pollution, which include diesel cars and wood-burning. Sarah Woolnough, chief executive of charity Asthma + Lung UK, said: “Air pollution is a public health emergency which causes 36,000 premature deaths in the UK every year. The government has ignored our calls to bring forward its compliance date, and instead said it will make our air cleaner by 2040. This falls far short of what’s needed – it means that for another 17 years, children will be forced to live, learn and play in toxic levels of air pollution, and a new generation will be condemned to breathe air so dirty it can stunt their lung growth, cause lung conditions like cancer, and trigger existing conditions including asthma.” Coffey also ruled out a ban on wood-burning stoves, opting instead for “educating” people on their use. There will be tighter regulation of new wood burners, which in designated “smoke control areas” will be allowed to pour out no more than 3g of smoke per hour, instead of 5g at present, but Coffey said she wanted to “avoid fingerpointing” by cracking down on existing stove users. Andrea Lee, campaigns and policy manager for clean air at Client Earth, said most people in urban areas had access to alternative ways of heating their homes, and should be encouraged to use them instead. She said: “There should be a phasing out of wood burning in urban areas.” Wood-burning stoves, which are usually expensive to install, are increasingly being used in urban areas for aesthetic reasons, and are now the main source of air pollution in many areas. Coffey also confirmed that there would be no major new funding for achieving the targets in the 262-page Environmental Improvement Plan, published on Tuesday, beyond a multimillion-pound new fund to protect some species including hedgehogs and red squirrels. Some farming leaders have said new sources of funds would be needed to encourage farmers to take up greener methods. But Mark Spencer, the farming minister, told the Guardian that farmers were already receiving £2.4bn of public payments a year, and this should be enough. “People in agriculture want to have a really positive impact on the environment, and we need to get them on the ladder of aspiration,” he said. “We are pushing on an open door with lots of farmers in the UK, they think all the time of the environment. It’s a privilege to be farming and working in the UK’s beautiful landscape.” Campaigners also called for the government to make it mandatory to build green space into new developments. Ministers have pledged to ensure that every home has access to a green space or water within a 15-minute walk, and to that end Natural England is drawing up a comprehensive map of green spaces. Tony Juniper, chairman of Natural England, said: “What we have discovered by undertaking this map is that some of the most deprived communities have least access to green space. Environmental improvement is also a levelling out of some of the inequalities in this country.” Richard Benwell, chief executive of the conservation group Wildlife and Countryside Link, said that local authority planners should be obliged to include access to nature and green spaces in new planned developments. “Too many people live in polluted, nature-deprived neighbourhoods, at great cost to mental and physical health,” he said. “Billions of pounds could be saved for the NHS if everyone lived in a healthy environment, and millions of lives could be brightened.” The EIP set out on Tuesday includes targets and measures to remedy a wide variety of environmental problems, from species loss and air and water pollution to waste and recycling. It is a requirement under the Environment Act, and is meant to set out an achievable blueprint. It followed criticism last week from the statutory watchdog, the Office for Environmental Protection, that the UK was failing or showing little progress on nearly every environmental measure. Dame Glenys Stacey, chair of the OEP, told the Guardian on Tuesday she welcomed the EIP. But she added: “It’s all about delivery now. The targets are good, but we need to see delivery.” Many green activists were concerned at gaps in the plan, pointing out for instance that although it contains stipulations for fitting dual flush toilets, it does little to force water companies to stop pouring sewage into rivers. Doug Parr, UK policy director at Greenpeace UK, said: “If this is a roadmap, it’s a roadmap to the cliff edge. This Conservative government promised the most ambitious environmental plan of any country on earth. Instead, here’s yet more paperwork containing a threadbare patchwork of policies that fail to tackle many of the real threats to our natural world. This won’t do.” Jim McMahon, Labour’s shadow environment secretary, said: “Since [Coffey] has been in post, the Conservatives have breached a statutory deadline for publishing environmental targets, shown a lack of interest in the sewage scandal by refusing to meet water bosses, and announced measures that inflict more sewage dumping and toxic air on our country for longer.”