hydrogen fuel

This is a chemistry/technology kind of question. What would happen if a fuel cell is supplied with a hydrogen purity below the rated value? Would low purity hydrogen damage some fuel cells or the stack, or accelerate the degradation?

I drive a Honda Clarity fuel cell car and am located in Davis (just west of Sacramento). We have (a) the one original (Linde; now Iwatani-purchased) hydrogen fuel pump in West Sacramento and (b & c) two new 2019 (Shell) pumps in Sacramento. Throughout 2017 and most of 2018 (despite there being...