The graph above also helps us to determine where are possible origins of suspended particulates in the ambient airs (PM2.5, PM10 or even PM100).
Uncoverred construction with a strong wind can sweep up fine sand and dust from construction sites. While heavy use of fertilizers nearby could provide nitrate and ammoniuum salts to the atmosphere. More abundantly, combusions espcially diesel engine emits carbon soots that contributes to the formation of fine (PM2.5) or untrafine particles.
This method simply means to measure the weight of a filter before and after a period of sampling, in which ambient air is drawn in by a pump with a pre-filtering apparatus to only select the target size of particulate matter.
The best resource I found is Notice 32/2013/TT-BTNMT by Vietnam MONRE on Issuance National Standards on Environment. The document constains 4 National Standards (QCVN). For PMs sampling method, look for QCVN O5:2013/BTNMT.
For PMs, here is a list of methods for sampling amd measuring:
For the US, the concentration of PM2.5 is mandated by the Code of Federal Regulations by CFR § 50.7 which also provides a reference and a equipvalent methods.
The mass of particles collected into a filterr results in change of oscillating mass and hence, the oscillating frequency. If we know the frequency and mass at time zero and the time t, using gravimetric method to calibrate the TOEM method.
Pure materials such quart have a defined mechanical resonances, and the resonance frequency is a function of mass. Therefore, we can compare the resonance frequency with dust deposited on a crystal with a control crystal and determine the mass of deposited dust.
BAM technology accounted the loss of electrons as they penetrated through a filter. By comparing a blank filter (or the filter at time zero), we can determine the mass of dust that results in the loss of electrons from the source.
Dust deposited into a filter results in increment of headloss or a drop of pressure head.
By illuminating particles by a light source, light scattering in accordance to Mie Scattering effects. The mass of particles can be correlated by using a fitering method or by electromagnetic theory.
Nephelometers quantify particle light scatting over all directions.
Similar to Visible Light Scattering method, this method quantifies of particles in an air stream by counting number of particles and the sizes with an assumed mass density.
This method is applied for untrafine particles by growing their sizes to the level can be detected by light scattering.
This method measures both light scattering and time-of-flight of particles.
LIDAR measures light scattering in the the direction of the light source. First, a pulsed laser sends to the atmosphere and the receiver, located closed to the emitter, the scattered light back by the suspended particles.
Diurnal variations: such as mixing close the ground level as the result of solar heatting/cooling.
Wind Speed: Wind speed is the indicator of the convective transportation.
Source Directionality: in combination with speed and direction.