|“||Should last around 20 minutes... but if more than 4 hours call your doctor.||„|
All filters are universal and fit any gas masks found in the metro, and they're widely traded throughout the settlements. Anyone regularly traveling between Metro stations or the surface should carry these.
These filters are likely charcoal filters as charcoal is a natural poison adsorbent, and can be found and made just about anywhere. This may also be the reason why they don't last very long, since the technology to make more advanced filters was likely lost after the disaster or it is prohibitively difficult and expensive to mass produce better filters due to the scarcity of the resources and expertise that are required to make them.
Filters can be found just about everywhere in the Metro:
- They're traded in a few settlements (Riga and Market).
- They can be found on corpses.
- Given to Artyom by some other NPCs
- Can be found as individual filters in various locations in the Metro and surface.
- Can be found in wooden supply crates/boxes throughout the game.
- Will come attached to recently swapped Gas Masks.
The player must use the filters in compliance with the gas mask, they must be swapped out regularly with a fresh filter every few minutes of continued use. A clean filter lasts almost exactly one minute regardless of difficulty played on or the activities being performed by Artyom (such as constant sprinting).
Artyom keeps a wrist watch on at all times to keep track of how much time his filters have left before they've become too used to entirely filter the toxic air. However, there are other signs that the filter may need to be swapped, if for example: Artyom's breathing becomes very heavy, the player can hear a wheezing that Artyom is struggling for air, Artyom's vision starts to tunnel or blur, then the filter may need to be changed, or another urgently looked for. When a filter runs dry, Artyom will automatically swap in a fresh one (though this event seems to be erratic in frequency). If the filters are not swapped out when needed, Artyom will slowly suffocate and ultimately die.
- In the game, if the gas mask becomes cracked, it reduces the air filters duration. In real life, a crack in the mask would not affect the filter at all; it would simply leak in poisonous air, in many cases making the gas mask useless. If the filter is damaged there is a chance that it has less usage time, but it will most likely be useless.
- Most filters you find can't be picked up because they have been used or the filter is expired.
- The filters are shown in a very weird way. The units showed are not filters, but rather minutes of time. But still when buying a filter, one does not get 20 of these units.
- The filters last for a very short period of time (about 5 minutes), even though the air is still relatively clean, as the player can survive there for a brief-period of time.
- It's common that players run out of filters, so use your filters wisely and don't waste them or take too long in areas where you need to use the gas mask. In the level you must use the filters, pass them quickly to conserve filter. Also, you may want to spend MGRs for more filters in level like Market in Metro 2033 as in some part of the game that you will spend a long period of time on the surface.
- In Metro 2033, filters can only be bought in early parts of the game, at Riga Station and Market Station, so buying as much as you can is wise.
- Strangely, Rangers don't use filters on their gas masks.
- In Last Light and Redux version the gas mask used by Rangers has filters on it.
- The player can exploit the duration of the air filters by constantly putting on and taking off the gas mask. Since the player has a short period of time (up to 30 seconds) that he can go without a mask on, this time elapsed with the gas mask off can be valuable if the player is nearly out of time on his filter.
- The gas mask filters the player uses are very large (bigger than Artyom's hand), but the filters appear very small before being picked up. They are likely 60mm filters. In Last Light and Redux version the filters are larger, fixing this developer oversight.
- The Nazi gas mask and the Ranger gas masks are the same, but the Nazi masks have filters and a helmet over them, while the Rangers' masks are attached to their helmets.
- In Metro: Last Light the maximum amount of filters you can carry at one time is 59:59. (59 minutes, 59 seconds.) However, Artyom will refuse to pick up any filters that would put the total number higher than his limit. E.g. When carrying a total of 56:56, Artyom will not pick up any filters with over 3 minutes 3 seconds left on them.
- Each filter in Redux version lasts 5 minutes, like the Last Light version.