PM2.5 sensor gives erratic result in the office

[engineheat]

Hi,

I used a consumer grade air quality sensor to monitor the air quality at my office. This is the result at my cubicle:



As you can, the AQI is 240 and the PM2.5 is 190 ug/m^3.

But just a few steps away, at the hall way, here's the result:



The AQI in the hallway is 28 and PM2.5 is 6.8 ug/m^3.

I walked back and forth between the 2 areas and got similar result, so I'm really curious why. This is making me concerned.

This was done after most people have left, so no one is cooking or doing activities that might cause the discrepancy, and there isn't a printer or anything that can cause pollution nearby (that i know of)

I can only think of 3 reasons:

1. Some kind of electrical interference at my cubicle (there is a lab next to it, but I don't know what is in the lab).

2. They didn't change the filters in the HVAC and dirty air is being delivered to my cubicle (and my neighbors) because I got high reading at their desk too. But this isn't likely because just steps away in the open hall way the sensor reading is very low. You'd think with diffusion there shouldn't be that big of a difference.

3. The sensor uses a laser. Perhaps the florescent light that is over our cubicles is causing interference with the laser? Whereas in the hallway, the lights are much higher (further away) and I didn't notice whether it's florescent or not in the hallway...

This is a bit mysterious to me. Let me know what kind of tests I can do to figure out the cause.

I did use a different (more expensive) sensor and it gave similiar result at all locations (5 microgram/m^3) so I'm really hoping the high reading is a false alarm.

Thanks

[thm_w]

Take it apart and see what actual sensor is inside.
The cheap $5 sensors are garbage, they just have a IR LED or similar. The good ones will use a laser (see below).
It should not be possible for light to leak inside based on their design, black plastic with a maze to get in.

If you think its interference, plug the air inlet of the sensor to prevent air from entering, and the reading should drop to 0ug.

[coppercone2]

AH cubicals

it can be because they have a electrostatic charge from that fuzzy bullshit concentrating dust around you, like a force field. And your idea about HVAC being bad, well.. its true. Companies have to pay an arm and a leg for a 'commercial' service to work on HVAC. Its easily the most unmaintained thing in a building, because water, lighting and electricity gets complaints. HVAC only get complaint if it smells.


Basically i see a company doing absolutely 0 about air quality in an office and having their main thug fight you tooth and nail about any evidence you propose. You know the one with the creative analogies like "its not a _______ (hospital, nasa or other extreme example of supposed quality)".


it makes me laugh because the golden age of america (as often stated) seemed to have offices for everyone. They made it 'better' and now its dirty, noisy, and the economy aint doing shit for most people.

[coppercone2]

What I wanna see is a work place push on HVAC and facilities transparency.


 You know they want you to come in for no reason, but you never know if they changed the water filters, air filters, cleaned the ducts or did anything that you can't see from your chair. You have to trust one of their cronies to likely 'fudge' facts for you, 6 month becomes a year, 1 year becomes 36 months, 50% humidity turns into 65%, and so forth. Vacuuming, and sterilizing too. Its all cloak and dagger it happens 20% of the time the say it happens.

How about some charts about temperature too, so its actually workable when you come in, not "well we keep it at blah but on the weekend it was turned off so it will take till Tuesday to get it air conditioned again". Well shit, maybe have me come in on tuesday instead of Monday? Or if its fucking frigid.


facilities is the biggest fraud area for everyday work stuff. With HVAC questions or concerns your almost guaranteed to end up with a snake  . If you come across someone that actually checks out your HVAC concerns, value them.

your not even allowed to look. why the FUCK am I supposed to trust those people? Their reputation is mostly SHIT.

Its basically the field of skimming. They love skimming facilities. its like the god damn mafia

[SiliconWizard]

Could be the sensor, could be reality.
The particles may come from AC/ventilation indeed. Could come from the materials on walls, floors, or the cubicles themselves. Or, could come from some of your coworkers that are turning into dust, who knows.

I've never looked at PM in offices, but at CO2 and you'd be shocked. Air quality inside many offices is really poor.

[coppercone2]

maybe your co worker is decomposing because its loading access to a corporate server (since 1980)

[engineheat]

It's actually due to the fluorescent light at the cubicle area. I confirmed this and also talked to the manufacturer.

[coppercone2]

lol wtf.

what does it read if you put a light blocking object near it

I hate being near carpeted walls. Its like being in some kind of dried out moss cave.

[SiliconWizard]

You're already in some kind of cage in a cubicle.
Yes, the cage is open, but you just stay in.

[vicenzo]

As a new practitioner, I learned about this problem through this post. I don’t know if these products have built-in detection devices.