What I want to do
Scan dust & look for potential Asbestos Fibers.
Asbestos fibers are needle-like when viewed close up.
The image below shows what they are like in comparison to other types of mineral fibers.
From: https://www.osha.gov/OshStd_gif/zkf1.gif
They tend to be around 0.9µm - 10µm (micrometers) in size.
From: http://en.wikipedia.org/wiki/Asbestos
My attempt and results
This piece of sticky tape is 15cm*5cm.
This is what it looks like when scanned at 600dpi.
Fibers become more visible after applying the inverse color filter.
If you zoom in on the main article image, I have added a little ruler indicating that approximately 1mm = 15px on that image. It was scanned at 150dpi, thus accordingly, 300pid: 1mm = 30px & 600dpi 1mm = 60px.
At 600dpi:
1mm = 1000 micrometers. 1µm = 0.001mm.
60 px = 1000 micrometers. 1µm = 0.06px.
1µm (small asbestos fibers) - wouldn't render properly at this resolution.
10µm (large asbestos fibers) - could potentially show as 1px (as it is 0.6px- more than half a pixel) at this resolution.
With this kept in mind, anything with a resolution of 1000dpi+ is going to start capturing larger asbestos fibers.
There is already consumer access to flatbed scanners with this kind of resolution (&higher).
Questions and next steps
How can resolution be refined further? How can samples be taken in a way that produces a 'clean' image?
Update: I am working with the idea of having a piece of cardboard act as a window frame.
It isn't perfect, but the idea is:
- Unroll sticky tape & attach part you have touched to the bottom of the frame.
- Unroll carefully, trying not to touch the sticky tape, against the surface you wish to study.
- Carefully rub the back of the sticky tape against the surface.
- Unpeel the sticky tape from the surface and then continue rolling the tape to seal up the other side.
- Label the frame with the location, date & time.
- Scan & analyse.
Here is an example:
Why I'm interested
I want to know if this will be fruitful in serving as a basic indicator of the presence of asbestos fibers in the home.
If there are fibers present that even slightly resemble asbestos, then a concerned citizen could use this as a form of preliminary observation as justification to get further, more detailed testing done by an environmental hygienist.
12 Comments
The inverse helps make particles stand out. Another filter you might try is a threshold. If you're using GIMP (free and open source software for image manipulation), here's the menu option for threshold: http://docs.gimp.org/en/gimp-tool-threshold.html
In normal color mode, the histogram should show a sharp band on the right, representing the white background. You'll want to leave that marker. On the left side of the histogram, you might see a wider, shorter peak representing the different darkened objects. If you drag the black arrow to the right past that wide peak, everything that is sort of black should become jet black, highlighting it a little better. You can always invert after the threshold to help it stand out.
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@btbonval
Did you mean like this?
I used Paint.net > Adjustments > Levels and made it so that the Input histogram was between 255-240.
(*That is mostly cat hair, for those of you going "ewww gross" in reaction to that image)
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