Thanks. I don’t see the NOx that any of us might produce as intrinsically harmful. The NOx that a power plant might produce burning a fossil fuel may be of concern. It is emitted through a high stack and then can react with water high up in the atmosphere to produce nitric acid, which along with sulfuric acid can adulterate rainwater to produce acid rain*. I’m not sure that would apply near the ground, where our chimneys and roof vents are, and is a moot point, according to what you said.
*There is even some question as to whether acid rain was as harmful as it was said to be, as far as I know.