Poor air quality and climate change pose a bigger threat to people's health and the economy than coronavirus, NHS staff have warned.
BBC Wales has seen a letter sent on behalf of hundreds of healthcare workers to the Welsh Government.
It calls for environmental issues to be prioritised as part of a "healthy recovery" following the pandemic.
The Welsh Government said it was "committed" to a green recovery.
The letter calls for scientific advisors to be involved in developing economic policy in the aftermath of the pandemic.
Efforts to pedestrianise cities, encourage walking and cycling, and increasing how much energy is supplied by renewable sources should be sped up, it says, as well as businesses getting money to help cut energy consumption and waste.
Anaesthetic registrar at University Hospital of Wales in Cardiff, Dr Farzad Saadat, said: "What we're asking is that the government put clean air, clean energy and a cleaner environment at the centre of their policies for the future."
The Welsh Environmental Anaesthesia Network (WEAN), one of the organisations behind the letter, has worked with hospitals across Wales for the past 18 months to cut back on emissions of potent, planet-warming gases involved in treatment.
This has resulted in a cut of 130,000kg of CO2 per month "the same as flying to New York 130 times," said Dr Saadat, a WEAN member.
He added: "There's growing evidence, for instance, that air pollution makes us more susceptible to the disease and makes us more likely to have a bad outcome should we get it.
"There's convincing evidence too that diseases like Covid-19 are more likely to emerge as we destroy the natural world."
Ysbyty Gwynedd Green Group has also signed the letter.
Member Yasmina Hamdaoui, a pharmacist, said pollution could lead to - and exacerbate - cardiovascular and respiratory diseases, with possible links also to dementia and diabetes, as well as weight gain in babies and lung development in children.
"We've seen during this period that we have the ability to make drastic changes to our way of life when we need to. We want to learn from these changes and not just return to old habits."
She said the letter was inspired by another sent to leaders of the G20 countries by more than 350 groups representing 40 million healthcare workers.
"This is our attempt to do something at a more local level, join forces as Welsh organisations and call on the Welsh Government to make a commitment too," she added.
Air quality in parts of Cardiff ranks among the worst in the UK when population is taken into account, and government data shows Wales has the highest levels of CO2 per capita emissions in the UK.
"Our record to date hasn't always been the best," Dr Saadat said.
"While I do think the Welsh Government have been active, the reality is we have to do better - we don't have a choice."
Mathew Norman, of Asthma UK and the British Lung Foundation in Wales, backs the plan: "The cost of air pollution to our NHS is £1bn pounds a year - that's just in Wales.
"If we improve air quality, we're not just improving the nation's health and our environment we'll also be helping the NHS."
The circumstances surrounding coronavirus could provide an opportunity to "fast-forward" some of the changes required, he suggested.
"More of us are working from home, we've seen in Cardiff and elsewhere measures to transform the city centre, bringing in cycling infrastructure and pedestrianising whole streets. All of this will limit the amount of pollution we emit."
Tracy Cross, of Llanishen, Cardiff, has chronic obstructive pulmonary disease and asthma and said every breath was like "breathing through straws".
She has noticed a "huge change" in air quality during lockdown.
"It used to make my chest feel really tight and restricted and I had to risk assess every time I wanted to go out. But during lockdown it's been fantastic - I've been able to get out a lot more into the garden with my children."
Ms Cross said it was important things did not revert to "normal" as there would be many people with lung conditions who have lost fitness while shielding at home and deteriorating air quality would lead to "a lot more people suffering".
A Welsh Government spokesperson said it was "committed to a green and socially just recovery, leading to a cleaner, healthier and more equal nation".
"This recovery will require working with partners across Wales," they said.
"Our Team Wales approach already includes work with Natural Resources Wales who have created a panel to advise on this recovery work, and through the Partnership Council for Wales we have jointly set an ambitious target to achieve a net-zero carbon public sector in Wales by 2030.
"Air pollution is the largest environmental threat to public health.
"We will be publishing our Clean Air Plan for Wales this August, which reflects how we will deliver our commitment to reducing emissions and delivering vital improvements for health and well-being, natural environment, ecosystems and biodiversity."