Tackling climate change would save at least a million lives a year, the World Health Organization has told the UN climate summit in Poland, making it a moral imperative.

Cutting fossil fuel burning not only slows global warming but slashes air pollution, which causes millions of early deaths a year, the WHO says. In a report requested by UN climate summit leaders, the WHO says the economic benefits of improved health are more than double the costs of cutting emissions, and even higher in India and China, which are plagued by toxic air.

“The global public health community is getting very impatient,” said María Neira, WHO director of public and environmental health. “If you don’t think you need to take action for the sake of climate change, make sure when you think about the planet you incorporate a couple of lungs, a brain and a heart. It is not just about saving the planet in the future, it is about protecting the health of the people right now.”

The damage caused by coal, oil and gas pollution is “outrageous”, she said. “There are words not included in the documents at [the climate summit]: asthma, lung cancer, stroke, heart disease – they need to be incorporated in all the decision-making processes.”

“Morally, delaying the clean energy transition is being responsible for millions of deaths every year,” Neira said. “Leaders need to ask themselves how many deaths are they willing to accept. When health is taken into account, climate action is an opportunity, not a cost.”

Air pollution is the best known impact of fossil fuel use, and climate change damages health through heatwaves, storms, floods and droughts, increased spread of infectious disease and the destruction of health facilities. Global warming is also damaging crops and reducing their nutritional value, with the UN Food and Agriculture Organization now reporting a rise in the number of hungry people going up after decades of decline.

“We now have scientific evidence that people are suffering and dying from climate change,” said Prof Kristie Ebi, at the University of Washington and lead author on the recent intergovernmental panel on climate change (IPCC) report, that warned that the global temperature rise must be kept to 1.5C to protect hundreds of millions of people from harm. Another major recent report concluded that climate change is already a health emergency.

Diarmid Campbell-Lendrum, at the World Health Organization and also an IPCC report author, said doctors needed to press hard for climate action: “The health profession is the single most trusted profession in the world.” Just 0.5% of multilateral climate finance is currently going to healthcare, he said. Organizations representing more than five million doctors, nurses and public health professionals from 120 countries have issued a call to action to the climate summit in Poland.

“We should no longer be talking about the cost of cutting emissions, we should talk about the benefits to people’s health of investing in what needs to be done,” Campbell-Lendrum said.

“At the moment we pretend that polluting fossil fuels are cheap fuels, only because we don’t include the cost of them to our health and economy.” The IMF estimates these subsidies to the fossil fuel industry to be $5tn a year, more than all governments currently spend on healthcare.

Almost 200 nations are meeting in Katowice, Poland, for two weeks, aiming to turn the carbon-cutting vision set in Paris in 2015 into a reality, as well as increasing the ambition and speed of action and the funding needed. Current pledges leaving the world on track for a disastrous 3C of warming.