Washington: US President Donald Trump has accused China, India and Russia of not taking care of their "filthy air" as he justified America's withdrawal from the "unfair" Paris climate agreement.

Trump, a known climate change sceptic, wants to expand non-renewable energy. He aims to increase drilling for oil and gas, and roll back further environmental protections in America.

"Look at China, how filthy it is. Look at Russia. Look at India, it's filthy. The air is filthy," Trump said during the final presidential debate with his Democratic challenger Joe Biden in Nashville, Tennessee on Thursday night.

"We have the best emission numbers that we've had in 35 years under this administration. We are working so well with the industry, he said responding to a question on climate change during the debate that lasted just over 90 minutes.

Trump has repeatedly blamed countries like India and China for not doing enough on climate change, labelling them as regions with air that is impossible to breathe.

Reiterating that he loves the environment, Trump said he wants cleanest, crystal-clear water, the cleanest air. "We have the best, lowest number in carbon emissions, which is a big standard that I notice (Barack) Obama goes with all the time, not Joe. I haven't heard Joe use the term because I'm not sure he knows what it represents or means, but I have heard Obama use it," he said.

"The Paris Accord, I took us out because we were going to have to spend trillions of dollars and we were treated very unfairly. When they put us in there, they did is a great disservice. They were going to take away our businesses," he asserted.

In 2017, Trump pulled the US out of the 2015 Paris climate agreement, saying the international deal to keep global temperatures rises below 2 degree Celsius was disadvantageous to US workers.

Biden, on the other hand, said that if voted to power in November, he would rejoin the historic Paris agreement on climate change and hold countries like China accountable for pollution.

Trump has continuously argued that countries like China and India are benefiting the most from the Paris agreement.

Speaking to his cheering supporters at an election rally in the key battleground State of North Carolina last week, Trump had blamed countries like China, Russia and India for adding to the global air pollution.

"We have the best environmental numbers, ozone numbers, and so many other numbers. In the meantime, China, Russia, India all these countries they're spewing stuff into the air, he alleged.

China is the world's biggest carbon emitter followed by the US, India and the EU.

Trump's latest comments come at a time when pollution levels in New Delhi dropped to the 'very poor' category and are likely to worsen in the coming days. Delhi's Air Quality Index (AQI) has been recorded at 302, which is in the 'very poor' category.

Trump asserted that he will not sacrifice tens of millions of jobs, thousands and thousands of companies, because of the Paris Accord.

"It was so unfair. China doesn't kick in until 2030. Russia goes back to a low standard. And we kicked in right away. It would have destroyed our businesses, he said.

"We have done an incredible job environmentally. We have the cleanest air, the cleanest water, and the best carbon emission standards that we've seen in many, many years, Trump claimed.

Biden, in response to the same question on climate change, said global warming is an existential threat to humanity.

"We have a moral obligation to deal with it. We are told by all the leading scientists of the world we don't have much time. We're going to pass the point of no return within the next eight to 10 years," he said.

"Four more years of this man eliminating all the regulations that were put in by us to clean up a climate, to limit emissions will put us in a position where we're going to be in real trouble. Here's where we have a great opportunity. I was able to get all the environmental organisations as well as labor, the people worried about jobs, to support my climate plan, because what it does, it will create millions of new good paying jobs," he said.

Biden said that his administration is going to invest in 50,000 charging stations on our highways so that they can own the electric car market of the future. In the meantime, China is doing that, he said.

"I'll create USD 1 trillion more in economic growth than his proposal does, not on climate, just on the economy," he said.

"I'm gonna rejoin Paris Accord and make China abide by what they agreed to (On Paris climate accord), Biden said as he changed his known position on fracking and said that he would transition from the oil industry pollution because it pollutes significantly.

"I would transition from the oil industry," Biden said.

Describing it as "a big statement", Trump urged people of oil-economy States like Texas to take note of it.

"It has to be replaced by renewable energy over time. And I'd stop giving to the oil industry; I'd stop giving them federal subsidies, Biden responded.

The former vice president alleged that Trump takes everything out of context. "But the point is look, we have to move toward net-zero emissions. The first place to do that by the year 2035 is in energy production. By 2050 totally, he said.