430 mg/m^3 is an extremely high concentration. That's almost half a gram in a box 3.3 feet on a side. I doubt there's even 1/10-gram in a 4 x 4 inch piece of galvanized screen. Add that to dilution in the great outdoors and you *might* get a concentration of 5 mg/m^3 directly in the exhaust plume of the stove when the screen is brand new. The only problem might be if you are using the stove inside the tent.
Of course, all this is coming from a guy who gave himself mild lead poisoning because he was using tin/lead solder in a tiny windowless room with inadequate ventilation (read: none) for 2 months. If it hadn't been for the headaches, I would still be clueless!