Nitric Oxide was discovered in 1772 by a British man named Joseph Priestly, who referred to it as “nitrous air.” When he discovered this, it was a colorless and gas and a toxic gas. Nitric Oxide continued to recieve the label of being a toxic gas and an air pollutant until over two hundred years later, in 1987, when it was proven to be naturally produced by the body of mammals, including humans.