Well, naturally, in the sense that naturally occurring chromium was converted to its very dangerous hexavalent state by the intense heat of the fire(s).
The that this hexavalent chromium is ultimately of natural origin and not man made does not make this any less of a concern.
If you're going to wear N95, you might as well wear a P95 instead which is better, with an optional activated carbon layer in it too. Remember to replace it from time to time.
The only difference between N95 and P95 (and R95) certification is the resistance to oil. There is no difference in particulate filtration. There will be a difference in cost though.
3M 8577 is a disposable P95 that is not bad. Obviously it's effective only if it's worn sufficiently tightly around the face. I wear it for a few weeks before it gets dirty and then I replace it.
For professional work, there are half-face ones that may be more comfortable to wear for long periods, but don't expect to wear this among people. You can even use it with a P100.
