The sampling method of indoor inhalable particulate matter (PM) sampler is used to monitor fine particulate matter (PM2.5, PM10, etc.) in the air, especially those particles that can enter the human respiratory system and pose potential health hazards. The following are common indoor particulate matter sampling methods:
1. Selection of Sampler
According to the particle size range, different types of particle samplers can be selected:
PM10 sampler: used to collect particles with a diameter less than 10 microns.
PM2.5 sampler: used to collect particles with a diameter less than 2.5 microns, commonly used for indoor air quality monitoring.
Total suspended particulate matter (TSP) sampler: used to collect all particulate matter in the air.
2. Sampling method
a. Gravity settling method (commonly used for TSP sampling)
This method allows particulate matter in the air to deposit on the filter membrane for sampling.
Install a specialized sampler indoors to collect particulate matter by settling it onto filter paper through gravity.
b. Inertial grading method
By using air velocity control and particle size classification technology, larger particles are blocked by inertial forces when passing through the sampler, while smaller particles can pass through specific classifiers.
According to the different particle sizes, the sampler has different filter membranes to capture particles of specific sizes.
c. Thermodynamic method (commonly used for PM2.5 sampling)
Using a suction device with a specific wind speed, particulate matter in the air is filtered and collected in stages according to particle size.
This method is suitable for more precise PM2.5 monitoring.
3. Sampling process
a. Install sampler
Choose a suitable sampling location, usually located far from the pollution source, but ensure that it can represent indoor air quality.
The sampler should be securely fixed to ensure stability during the sampling process, free from interference from external wind speed and temperature changes.
b. Set traffic and sampling time
Determine sampling flow rate: The flow rate is usually set between 10-30L/min, depending on the design of the sampler and sampling standards.
Set sampling time: usually 24-hour continuous sampling, or set different time periods according to standard requirements.
c. Air flow regulation
Adjust the air flow rate of the sampler to ensure compliance with standard methods and instrument instructions.
d. Sampling begins
Start the sampler and ensure stable air flow during the sampling process.
Regularly check the working status of the sampler to avoid malfunctions.
e. End sampling
After the sampling is completed, turn off the sampler and take out the filtered sample.
Pay attention to the preservation of samples and avoid external influences on particulate matter.
4. Data analysis
After the sampling is completed, the mass of particulate matter collected on the filter membrane is analyzed through weighing, chemical analysis, and other methods.
Calculate particle concentration: Particle concentration=mass of particles on the filter membrane/volume of sampled air.
5. Maintenance and calibration of samplers
Regularly maintain and calibrate the sampler to ensure the accuracy of the sampled data.
Check the replacement of filter membranes, calibration of flow meters, and cleanliness of equipment to avoid errors.
6. Precautions
Sampling environment: Ensure that there are no severe temperature fluctuations or airflow interference in the sampling environment to avoid affecting the sampling results.
Selection of filter membrane: The filter membrane should have good particle capture efficiency, and commonly used materials include glass fiber filter membrane, polyester membrane, etc.
Data comparison and analysis: Comparing and analyzing with outdoor environmental data can better understand indoor particulate matter pollution sources.
7. Common standards and specifications
China: Indoor Air Quality Standards (GB/T18883-2002), Environmental Air Quality Standards (GB3095-2012), etc.
International: WHO Indoor Air Quality Guidelines, EPA standards, etc.
The sampling method for indoor particulate matter needs to be determined based on actual detection requirements and standards to ensure that monitoring data accurately reflects indoor air quality. If you have specific instrument or method requirements, I can provide further relevant information.