Total Suspended Particulate (TSP)

Particulate matter (PM) is one of the six criteria air pollutants identified by the US EPA. They define particulate air pollution as an air-suspended mixture of both solid and liquid particles. TSP includes airborne particles > 10µm (micrometers) in diameter.

Particulate matter comes from both human and natural sources. Natural sources include sea salt, wildfire smoke from forest fires, pollen, and mold. Human activities responsible for PM₁₀ entering the atmosphere include:

TSP does not have a specified size limit. Therefore TSP covers the full range of particle sizes, including smaller particulate sizes such as PM₁₀ and PM_2.5.

Particles above 10µm are not usually acknowledged in government health legislation, as our nose and throat filter them out. Instead, TSP is more a nuisance dust than a health risk. However, as TSP includes all particle sizes, the risks associated with PM₁₀ and PM_2.5, such as serious respiratory and cardiovascular problems, also apply.

Aeroqual offers perimeter monitoring options for continuous real-time monitoring of TSP in outdoor areas. TSP is commonly measured alongside PM₁₀ and PM_2.5, particularly at industrial sites requiring nuisance dust assessment and monitoring.

We offer two different technologies for monitoring PM: particle counting and nephelometry.

The PCX PM module comprises an optical particle counter that uses scattered light to size and count particles. The amount of scattered light is converted to a voltage pulse and the amplitude of that voltage pulse is calibrated to a particle diameter. The particles are assigned based on diameter to one of six particle count channels. Using a proprietary algorithm, particle counts for each size fraction are converted into mass measurements, providing continuous and simultaneous measurement of TSP.

The PCX module also includes a controlled heated inlet, and active flow control.

The PCX module performance specifications are given in the table below.

The PCX module features an automatic internal zero calibration. The module uses an internal zero filter and pump to perform a zero calibration. The zero calibration can be triggered on start-up, placed on a continuous schedule, or manually triggered on the Aeroqual Cloud platform. Correct maintenance ensures the auto zero function operates correctly and prevents negative readings. The automatic zero calibration can be verified in the field by using an external filter placed upon the inlet.

The PCX module can be returned to Aeroqual for factory span calibration. This is recommended every 2 years.

The module can be field calibrated by co-locating it alongside another PM instrument of equal or better performance.

Aeroqual can also offer its patented remote calibration procedure, MOMA, for this module, which avoids the need for a site visit while also maintaining traceability to nearby regulatory air monitoring stations. See your Aeroqual representative for more information on this software tool.

High humidity can lead to inaccurate measurement from an optical particle sensor if not mitigated. This is because high humidity (including fog) causes aerosol particle growth through adsorption of water vapor, which can lead to erroneously high measurements by the particle sensor. However, the PCX module contains an inlet heater which reduces the sample air humidity and prevents the particle growth. This maintains the accuracy of the PM measurement even when the water content in the air is very high.

The PCX module contains two pumps, both expected to last between 18 months and 2 years of continuous operation. The module particle filter needs to be replaced every 6-12 months. The module also contains a laser and a photodetector, requiring factory calibration every 2 years.

The PM nephelometer module combines a laser nephelometer with a high-precision sharp cut cyclone to give accurate real-time measurement of ambient particulate matter. By changing the sharp cut cyclone, the particle sensor can be used to measure TSP. The sharp cut cyclone physically selects particles of a target size, ensuring precise measurement of only the size fraction of interest.

Following particle size selection, the sample stream is sent to the nephelometer module. A nephelometer is an optical sensor that uses light scattering to measure particle mass. The light source is a visible laser diode and scattered light is measured in the near forward angle using focusing optics and a photo diode.

The nephelometer has an on-board temperature sensor that corrects for thermal drift, a sheath air filter to keep the optics clean, automatic baseline drift correction, and a fiber optic span system to provide a check of the optical components.

The PM nephelometer module features an automatic internal zero calibration. The module uses an internal zero filter and pump to perform zero calibration every 12 hours. Correct maintenance ensures the auto zero function operates correctly and prevents negative readings. The automatic zero calibration can be verified in the field by using an external filter placed upon the inlet.

The nephelometer optical engine can be returned to Aeroqual for factory span calibration, this is recommended every 2 years.

The module can be field calibrated by co-locating it alongside another PM instrument of equal or better performance.

Aeroqual can also offer its remote calibration procedure, MOMA, for this module which avoids the need for a site visit while also maintaining traceability to nearby regulatory air monitoring stations. See your Aeroqual representative for more information on this software tool.

High humidity can lead to inaccurate measurement from an optical particle sensor if not mitigated. This is because high humidity (including fog) causes aerosol particle growth through adsorption of water vapor which can lead to erroneously high measurements by the particle sensor.

However, the nephelometer module contains an inlet heater which reduces the sample air humidity and prevents the particle growth. This maintains the accuracy of the PM measurement even when the water content in the air is very high.

The Aeroqual manufactured electronics module responsible for data analysis does not contain any consumable parts and does not contain any components which might wear out or expire and should last between 3 to 5 years.

The Aeroqual manufactured pump module contains two pumps, both expected to last between 18 months and 2 years of continuous operation.

The MetOne manufactured nephelometer module contains filters which are changed as required, usually between 1 and 3 months. The module also contains a laser and photodetector, requiring factory calibration every 2 years.

The PMX sensor head comprises an optical particle counter that uses scattered light to size and count particles. The amount of scattered light is converted to a voltage pulse and the amplitude of that voltage pulse is converted to a particle diameter. The particles are assigned based on diameter to one of six particle count channels. Using a proprietary algorithm, particle counts for each size fraction are converted into mass measurements for TSP.

The table below contains the PMX sensor head specifications. It can be used on our Ranger products.

In 2023 we compared the performance of the Ranger | Dust against the EN16450 certified Palas Fidas 200 using ISO 12103 A1 ultrafine test dust. The Ranger | Dust exhibited very similar performance to the certified Palas Fidas 200 reference instrument with ISO12103 A1 Arizona Road Dust . Its linearity was excellent with R² values greater than 0.99. Measurement error was very low - less than 5% - for all size fractions PM₁ to TSP. Read the full report here.