"Blue smoke" sounds like the spell cleansing aura.
Check your mages to see if any of them have it active.
As mentioned in another answer, they likely cast the spell because someone in the party was injured.
However, my experience is that only the initial casting of the spell removes injuries, not the persistent "aura" effect which heals hit points.
So if you see the aura and are still injured, you need to turn off the aura, wait for the cooldown, then cast it again with your injured party member in range in order for it to remove the injury.
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Blue smoke as in you have a spell active?
Can you post a screen shot?
If you're coughing blood use a injury kit to heal yourself and see if the smoke goes away.
IIRC
when you have certain spells active they aren't listed as under the modifiers as that's only for something that is physically affecting you i.e ice enabled, that should list there, but other spells, say spell might iirc won't.
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Coughing blood is a modifier caused by an injury so it should not be related to the blue smoke.
Apply a heal kit to your party member who has the coughing blood modifier and that should cure it.
It sounds like a Spirit Healer (mage) who is casting cleansing aura , however be aware that Cleansing Aura will not remove an injury on the Spirit Healer themself While this mode is active, waves of healing and cleansing energy emanate from the caster, restoring health to all nearby allies every few seconds and curing the injuries of allies very close to the caster.
For more information on injuries such as coughing blood, click here
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Note that if you use a lesser injury kit instead of a normal one it will get rid of other injuries so you might want to use more than one or use a greater injury kit unless he/she only has one injury.
And it might take a while before you have cleanse aura.
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it is a bug that happens when a specific sustained talent(I don't remember the name of the sustained talent) remains active after a cut scene occurs at the end of the battle.
Just save , exit game and load, that solved my problem
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You have two different problems: The blue smoke: fix using a templar's ability to Cleanse Area to make the smoke disappear (this will also cancel any other sustained mage abilities)
Coughing blood: use an injury kit.
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I just successfully defended Redcliffe in Dragon Age Origins as a Mage.  I noticed that there is some blue smoke surrounding me, but looking at my 'modifiers' the only thing I can see is 'coughing blood'.  Is the blue smoke a glitch or is there something which might cause it?
Blue smoke surrounding me in Dragon Age: Origins
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The Blue smoke is the spall cleansing aura. It is a bug that happens when a sustained talent remains active. For coughing blood, use an injury kit. While the issue could be  that it is a cleaning aura that can be fixed using the cleanse area ability, you could try using the Cleanse Area abiliy to fix. It could also be a bug you can fix be exiting and rejoining. As for the coughing blood, use an injury kit.
Users think it has to do with a spell cleansing aura and suggest using the cleanse area ability User thinks it is a bug that can be fixed by exiting and rejoining Coughing blood can be fixed by using an injury kit