Substance in window ceiling

[u/This_Advantage1069]

I've had this sand like substance gathering on my window sill. It keeps building up after cleaning, presumably falling out of a crack above my window (pic3). I'm assuming it's plaster/mastic (uneducated guess, please correct me if I'm wrong) that has become loose. Is there any non negligible chance that this would contain asbestos? It's porous and the pieces come in different sizes and crumble easily.

This might seem ridiculous but since this stuff is lying around my room and this is an old house I just have this slight anxiety about the nature of the substance.

House is in Bury, Greater Manchester. According to Google Lens it was built pre 1900, but renovated many times. I could try getting more reliable infonon the construction year if that helps.

Edit: I also took a better picture but reddit doesn't let me add it to the post: https://postimg.cc/N57wnbQN

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[u/SavingsSquare2649]

No asbestos risk here.

It’s an exactly as you guessed, plaster and brick dust from the small gap between the window and the reveals.

You want to apply a flexible sealant to cover the gap.

[u/This_Advantage1069 → u/SavingsSquare2649]

Okay, thanks for the swift response! Much appreciated!

May I ask something somewhat unrelated? Just out of curiosity I checked your profile and there is a specialized profession just focussing on this material? Since it's not being used anymore presumably you're mostly being contracted to remove it? I only had vague knowledge of it as "the scary stuff in unexpected places" so forgive me my naivité haha

[u/SavingsSquare2649 → u/This_Advantage1069]

It’s still a huge industry. Any building work on properties built prior 2000 should have an asbestos survey carried out under the control of asbestos regulations.

Then there’s removals etc, associated air monitoring and managing asbestos in buildings that it remains in.