HOW DO WE DETECT THEM INVISIBLE STUFF?

First, we collect them!
How?
Use: pre-weighed 47 mm Teflon Filter
1. Filter sample air at a constant through the Teflon Filter for 24 hours
2. Label the sample
* Make sure the used filter, now the sample, do not get contaminated by taking all neccesary precaution and following all proper handling of the sample. Disposable, powder-free gloves should be worn while handling filters both in the laboratory and in the field. Inspection of the individual filters should be conducted prior to use to ensure integrity of the filters.

3. Use a BAM (Beta Attenuation Monitor) or TEOM (Tapered Element Oscillating Microbalance)

BAM (Beta Attenuation Monitor)         TEOM (Tapered Element Oscillating Microbalance)        



     

1. The BAM or TEOM should be placed on a flat surface beneath the opening in the roof, and a sampling line should be installed based on the manufacturer's recommendations. Typically, sampling kits are available from the vendors to assist in the proper installation of these monitors. A PM2.5 cyclone should be installed on the end of the sampling line to provide appropriate size selectivity.
2. Set recording interval. After installation the BAMs or TEOMs should be configured to operate according to the manufacturer's recommendations and should be set to record data at least hourly. The sampling flow rates should be verified and other manufacturer's recommended diagnostics should be checked to ensure proper operation.

4. Gravimetric Analysis

1. Filters should be equilibrated in a temperature and humidity controlled laboratory, as specified in the Reference Method, for at least 24 hours prior to both pre-sample and post-sample weighing. 

Mean RH must be held between 30 and 40 percent, with a variability of not more than ±5 percent over 24 hours. Conditioning is permissible at a mean RH within ±5 percent RH of the mean ambient RH, but in no case less than 20 percent RH. Mean temperature should be held between 20 and 23o C, with a variability of not more than ±2o C over 24 hours. 

2. RH and temperature should be measured and recorded on a continuous basis during filter conditioning (either by a recording hygrothermograph or by electronic instruments).

An appropriate analytical balance is required for the measurement of filter weights. The balance should be calibrated prior to each weighing session, and a variety of calibration and QC checks should be conducted during each weighing session to assure the quality of the gravimetric measurements.

Picture References:
http://www.ohio.edu/airquality/capabilities/ambient.cfm
http://www.analysersindia.com/Beta-Ray-Attenuation-Air-Particulate-Concentration.html