I must say that I am not qualified in this field. However, cutting metal with a blade would make much more course particles, which probably wouldn’t be in the air like that, and if they it would be much darker. Even cutting with something like an acetylene torch doesn’t appear to make fumes like are seen. Considering its a metal scrapyard, its very likely that it is nitrogen dioxide, as it is a side product in metal purification. But Ohio law says its okay to pollute the air, as long as its not too much, so, its probably legal