WASHINGTON—Citing the hazardous levels of carbon dioxide and other pollutants accumulating in the atmosphere, officials from the Environmental Protection Agency urged the nation this week to develop a new air source. “To ensure the continued health of our planet and our population, it is imperative that we come up with alternative sources of air before it’s too late,” said agency administrator Gina McCarthy, stressing the urgency of generating several trillion kilograms of fresh nitrogen and oxygen that the country could breathe.