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Metro 2033 > General Discussions > Topic Details
Proph Mar 6, 2013 @ 12:52pm
FAQ: How gas mask filters work, finally understood.
I have posted this as a guide. Here is the link. is

Since google searches for how the filters actually work in the game have come up with many varied responses, some of them contradictory, I thought I'd share the known facts here.

How much time is on a filter?

It varies, a random filter found in the game world will usually have about one minute of air time, whereas a filter bought from a merchant will have 10 minutes of air time. The time you have remaining on a filter is unaffected by your actions (running or jumping), but it is theorized that if Artyom is at "rest" (not breathing heavily, or even better standing near a fire to "calm" him) you will get more time on the filter when you swap one in. That is unconfirmed though, and doesn't seem to affect your total time available. It is important to note though that if your gas mask becomes cracked, your filter will get used up faster (unconfirmed).

How do I know how many filters I have remaining?

This information is not shown to you, and it seems to be irrelevant because you don't actually run out of filters, you run out of breathing time.

How do I read Artyom's watch?

The red hand which moves counter-clockwise will be either in the green, yellow, or red areas of the watch. It is a countdown timer that shows how many minutes of air time you have remaining on the filter that you are wearing (e.g. if it's in the yellow you have less than 10 minutes, red less than 5, and when it reaches zero Artyom automatically changes his filter).

Help! My watch is broken, it always says I only have one minute left on my filter!

Some people say that their watch is "broken" and never moves out of the red, this is probably because you're out of "good" filters and have to keep using filters that only have one or two minutes of air. If you buy a filter you'll see that the watch works, but since you can only buy filters at Riga or Market you're probably going to be stuck with bum filters for the rest of the game.

What is the number next to the gas mask icon? I've been told it's how much air is left on the filter.

Not quite. Artyom's watch is the only measure of how much time is on a filter, what the number below the gas mask icon shows is how much TOTAL filter time you have among all your filters. If it says 10 you have 10 minutes of air, and it can be with 10 filters that have only one minute left, or 1 filter with 10 minutes.

Is there a maximum amount of filtered breathing time you can have?

Yes, no matter how many filters you buy you can't get the amount of time you have remaining over the ~40 minute range. The reason it is not a set number is because if you buy a filter that puts you over 40 minutes you then can't buy another one, e.g. if you were at 31 minutes and bought a filter it would put you at 41, but buying another wouldn't put you at a max it just would expend the money and you would not get a filter. I theorize that the max possible you can get is 49, but I haven't been able to test this.

Why can I pick up filters some times but not all the time?

This is not something that is entirely clear. It is possible that there is a maximum amount of filters you can carry, but there is no way to know. What it seems though is that if you have a certain amount of time left total on your filters, then it won't let you pick up new filters (I usually need to have under 25 minutes of time left before it will let me pick up filters found outside).

Why do the filters I find only last one minute, but the ones I buy last 10?

It's either for gameplay challenge reasons, or realism. At the time the game takes place all the filters should be expired. It's possible that the crappy filters you find are meant to be used or expired, whereas the ones you buy are recently made. Gas mask filters are somtimes made with charcoal, so it's not unrealistic to assume that it is within the Metro citizen's capabilities to create new gas mask filters.

Where can I buy filters? None of the merchants sell them!

Only the merchants at Riga station and Market station sell filters. It's not known why, but it is certainly a frustration as you can't get new filters later in the game. Stock up early if you can. Note though that even the merchants who don't sell filters will still hawk, "Medkits! Filters! Knives!" since the sound file is not specific to the merchants.

Hope this helps some people.
Last edited by Proph; Jul 15, 2013 @ 8:45pm
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Showing 1-15 of 37 comments
The main thing is just KEEP MOVING. As long as you do not spend too much time in any one spot you will be fine. Also the game DOES give you filters when you need them, adds in that sense of urgency while not just punishing the player for not knowing they need to buy filters at market, even tho Burbon tells you to do specifically that. Can't wait for last light!!
Basim_90 Mar 11, 2013 @ 5:43am 
Good guide.Thx man
Cobaltleo Mar 19, 2013 @ 3:06am 
good guide, i'm new to the game, originally didnt think i would like it till my bro showed it to me.
B.I.T.C.H. Apr 23, 2013 @ 7:48am 
Nice guide. Helps with the confusion regarding found filters and why I'm able to replace filters every couple minutes (sometimes faster than 1 per minute) in Dead City.
mychaelo Apr 24, 2013 @ 3:35am 
Post this in guides section.

Another interesting question is your stealth indicator. Most people see the green light and they're like "Ha, so they can't see me now!" - No, they still can see you. When you're completely invisible, your watch doesn't show any lights at all (so called "black light"). To achieve the black light more often you should buy a stealth suit. BTW clock shows the real time of your PC, not the ingame time.
Proph Apr 24, 2013 @ 12:54pm 
Hmm, good idea. I'll post it in the guides.

And yeah the watch is pretty awesome in game. It's too bad it's not a real watch, and only EU collectors editions owners have a replica. :(
Proph Apr 24, 2013 @ 1:12pm 
Posted, it's under the Basic Gameplay section. Also added in that filters bought from Riga don't provide as much breathing time as the ones from Market.
Last edited by Proph; Apr 24, 2013 @ 1:12pm
howard.parker73 May 1, 2013 @ 10:59am 
my gas mask won'tcome off
Proph May 1, 2013 @ 3:29pm 
Yes, I've had that glitch before as well. Restart the level and you'll be able to remove it.
The Fat Man May 28, 2013 @ 11:41am 
When you buy the heay armor that has the helmet with it's own mask, how do I use the mask?
Last edited by The Fat Man; May 28, 2013 @ 1:39pm
AB_Attack May 28, 2013 @ 12:05pm 
Originally posted by howard.parker73:
my gas mask won'tcome off

Happened to me as well, when I ran out of filters it stuck to my face. So I had to play 1/3 of the game watching through a cracked mask. It was really difficult and frustrating. It came off after I had the next opportunity to buy a filter.
Last edited by AB_Attack; May 28, 2013 @ 12:06pm
Proph May 28, 2013 @ 11:34pm 
Originally posted by Hellfire554:
When you buy the heay armor that has the helmet with it's own mask, how do I use the mask?

The mask is not a gas mask, it's simply an aesthetic part of the armor.
Last edited by Proph; May 28, 2013 @ 11:34pm
michael-np May 29, 2013 @ 7:59am 
Just to mention, it IS possible to go through the entire game without ever buying filters at merchants. I just completed the game in ranger easy and did not buy a filter at all. Of course you will need to look around for them, but the game gives you what is needed. The only place I had troubles was in level outpost where I had only 1 min. left before I found some filters in some dead nazis cache. Before Dead city, when Bourbon ask you to get filters, one just needs to enter the shop and exit again, then Bourbon will give you his sparefilter, and there is plenty of filters to be found in Dead City level. I ended up with 15 min. air when I reached Dry Station. Ended the game with around 20 min. of air. So you don't need to stock up on filters.
SnappyVandal May 29, 2013 @ 7:36pm 
I´m trappped in the level where you finally return to the intro scene of the game, the Nosalis brke my gas mask and it did a checkpoint, now i can´t go further more, cause i die of the brken mask. Any ideas?
michael-np May 30, 2013 @ 3:09am 
Reload the level. Or you can grab another mask from a corpse beside a bus on the way to the tower
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Metro 2033 > General Discussions > Topic Details
Date Posted: Mar 6, 2013 @ 12:52pm
Posts: 37