[aprssig] APRS Air Quality Monitoring

[Ron VE8RT]

Living in an area that annually has forest fire smoke in the area I was
interested in this thread.  But I understand that burning forests in
this area release an arsenic compound in the smoke (decades of gold
refining here).  Are there affordable sensors that could detect this? 

  Ron VE8RT  Yellowknife, NT, Canada

On Sun, 11 Nov 2018 20:20:48 -0800
Scott Miller <scott at opentrac.org> wrote:

> 
> > My guess is this sensor works differently than the others you have worked with. I believe it is a laser that measures the light scattered at different angles. The bigger the particle the more light will be scattered at larger angles. It has quite a large chamber (3 inches on a side) and uses a small fan to exhaust the chamber.
> 
> I haven't seen one with multiple detectors, but that sounds like a 
> nephelometer - they measured reflected off-axis light.  Apparently you 
> calibrate them with Arizona road dust...
> 
> > I'm curious about the sensors you are talking about. While I could understand methods that depend on a calibrated flow, e.g you could get particle concentration by counting particles passing a point, I would expect that increasing the flow would increase the count, raising the sensitivity of the sensor rather than decreasing it. I don't see how increasing the flow could decrease the sensitivity. What am I misconceptualizing?
> 
> The moving air isn't what's measured - it's just a laminar flow over the 
> optics to keep the dust off.  That seems to be the tricky part.
> 
> Scott
> N1VG
> 
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-- 
Ron VE8RT <ve8rt at yknwt.ca>