The declaration vows to prevent, mitigate and manage various forms of pollution. It begins by warning citizens across the world: "Every day, 9 out of 10 of us breathe air that exceeds WHO guidelines for air quality and more than 17,000 people will die prematurely because of it."
At a time when many Indian cities have hazardous levels of air pollution, India remained one of the focus countries at the UN Environment Assembly held in Kenya's Nairobi.
"UN can only inspire and motivate nations. Final decision on action has to come from the respective government. A lot of focus has been on air pollution in India off late," UNEP Executive Director Eric Solheim told reporters.
"Agricultural waste is being burned instead of treating it in the proper manner in Punjab, Haryana. But Harsh Vardhan (Union Environment Minister) has shown a keen interest in the declaration proceedings," Mr Solheim said.
India has also signed a resolution against air pollution, which kills one in nine people globally, and has committed to taking stringent action against the killer air.
"Just a few days back a cricket match had to be stopped in India. What can possibly signify worse levels of pollution, that you can't even play a sport?" said Rob De Jong, Air Quality Coordinator at UNEP.
"The pollution levels in several cities in India and China are several levels higher than the permissible levels," Mr Jong said.
Dia Mirza, the newly appointed United Nation's Goodwill Ambassador for India, hit out strongly at India's alleged inaction in dealing with air pollution.
"Since the time air indices were showing the air quality levels crossing 300, I have been saying that we must curtail exposure. Holding rallies, marathons and public meetings only compound the situation," she said.
"Why are we refusing to acknowledge this as a real issue? It's unfortunate. But right now we should not be entertaining large gatherings, exposing them to this bad air," Ms Mirza said.