Draught from double glazing

[Roger465]

I've just noticed a tiny draught when I put the back of my hand down to the corner of the sill and, as you can see, a small amount of dust blows through. when there's a strong wind.

It doesn't really annoy me - can't feel it in the room - but I've had problems with other windows fitted by this firm, so I'm wondering if this is something normal (maybe coming through from the little drain on the outside that all these windows have), or is there's likely to be a problem?

I examined the external seal all around the frame, and it looks OK, but I'm no expert

PS there isn't a big crack in the corner - just my bad painting

 

[Wayners]

Air blowing in from cavity

 

[diy_fun_uk]

Run a small bead of sealant along the bottom edge.

 

[Roger465]

Air blowing in from cavity

So... that doesn't mean there's a problem with the external seal...?

 

[Wayners]

Sorry. I ment maybe not. Just air blowing in cavity as normal. No cavity closer fitted @Roger465

That could be coming through window gap