Exposure to air pollution kills seven million people worldwide every year and costs an estimated $5.11trn in welfare losses globally, a report launched last week revealed.

It highlighted that in the 15 countries that emit the most greenhouse gas emissions – and have the worst air pollution – health impacts are estimated to cost more than 4% of GDP.

In comparison, actions necessary to meet the goals set out in the Paris Agreement would cost around 1% of global GDP.

“The true cost of climate change is felt in our hospitals and in our lungs,” said Maria Neira, WHO director of public health, environmental and social determinants of health.

“The health burden of polluting energy sources is now so high that moving to cleaner and more sustainable choices for energy supply, transport and food systems effectively pays for itself.

“When health is taken into account, climate change mitigation is an opportunity, not a cost.”

The WHO report highlighted that not enough investment focused on protecting people’s health from the impacts of climate change.

Global action to protect health from the impacts of climate change was “woefully inadequate”, particularly for small-island developing states and the least developed countries.

Just 0.5% of multilateral funds for climate change adaptation have been allocated to health projects, the WHO found.

Pacific island countries contributed 0.03% of gas emissions but are “among the most profoundly affected by its impacts”, the WHO said.

Joy St John, assistant director-general for climate and other determinants of health, said: “We now have a clear understanding of what needs to be done to protect health from climate change – from more resilient and sustainable healthcare facilities, to improved warning systems for extreme weather and infectious disease outbreaks.

“But the lack of investment is leaving the most vulnerable behind.”

The report called for countries to account for health in all cost-benefit analyses of climate change mitigation and to use fiscal incentives, such as carbon pricing and energy subsidies, to incentivise sectors to reduce their emissions of greenhouse gases and air pollutants.

The report added that the “main driver of climate change” is fossil fuels, which are also a major contributor to air pollution.

It called on countries to switch to low-carbon energy sources, which will improve air quality as well as offer “immediate health benefits”.