I'm out of filters and keep choking to death

I'm at the part of the game where you're on the surface fighting Nazis, specifically in the big area with all the old cars and the spotlight.

I ran out of air filters in the previous area and now I just choke to death and respawn at the checkpoint, is there a hidden air filter somewhere or should I just keep going?

Also, advice for preventing this in the future would be much appreciated!

Im fairly certain the game is designed to not allow this to happen. If it keep happening and you reset at the checkpoint enough it just adds minutes onto your filter time to enable you to get through the section.

If this doesnt work then a workaround it you can take the mask off and put it back on which gives you around 8 seconds of air each time. Simply repeat this until you find more air filters.