Formula & Calculator
Particulate Matter Mass Concentration
Calculates the mass concentration of airborne particulate matter (e.g. PM2.5, PM10) from a filter sample's collected mass and sampled air volume.
Interpretation
C = m / V. The mass of particulate matter per unit volume of air. Used in air quality monitoring and occupational hygiene.
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| C | Particulate mass concentration | µg/m3 |
| m | Mass of particulates collected on filter | µg |
| V | Volume of air sampled | m3 |
What it means
Particulate matter (PM) concentration is the mass of particles per unit volume of air, typically expressed in µg/m³ or mg/m³. It is measured by collecting particles on a filter and weighing the mass (m), then dividing by the volume of air sampled (V). This is the fundamental measurement for PM10, PM2.5, and total suspended particles (TSP). It is used to assess compliance with air quality standards, to evaluate health risks, and to design control measures. Example: A sampler draws 24 m³ of air through a filter over 24 hours. The filter gains 0.00012 g (120 µg) of particles. Concentration = 120 µg / 24 m³ = 5 µg/m³. This is well below typical standards and indicates good air quality.
Worked example
PM Mass Concentration – Two Examples
Real‑World| Parameter | Value |
|---|---|
| Mass | 150 µg |
| Volume | 10 m³ |
| Parameter | Value |
|---|---|
| Mass | 300 µg |
| Volume | 15 m³ |
Common mistakes
- Mass m: The mass of particulate matter collected – in µg or mg.
- Volume V: The volume of air sampled – in m³ (or L – convert to m³).
- Units: C = m/V – e.g., µg/m³.
- Sampling conditions: Volume must be corrected to standard conditions (e.g., 25°C, 1 atm) for comparability.
- Filter handling: Weigh filters before and after sampling under controlled humidity and temperature.
Applications
Particulate matter mass concentration is the mass of particles per unit volume of air, typically expressed as µg/m³. It is obtained by dividing the collected mass (m) by the volume of air sampled (V). This is the fundamental metric for air quality monitoring of PM₁₀, PM₂.₅, and total suspended particulates. Environmental and occupational hygienists use gravimetric sampling to assess exposure, to evaluate the effectiveness of dust control measures, and to ensure compliance with air quality standards. The formula also supports the calibration of continuous particulate monitors. Accurate concentration measurement is critical for protecting public health and for informing regulatory decisions on emission controls.
- Ambient air quality monitoring for PM₁₀ and PM₂.₅
- Occupational exposure assessment in mining, construction, and manufacturing
- Evaluation of dust control measures in industrial operations
- Calibration and validation of continuous particulate monitors
- Epidemiological studies linking particulate exposure to health effects
Frequently Asked Questions
The mass concentration (C) is calculated as C = m / V, where m is the mass of particulate matter collected on the filter (mg) and V is the volume of air sampled (m³). The result is in mg/m³.
Forgetting to subtract the pre‑weighed (blank/tare) filter mass. The mass m is the difference between the final and initial filter weights. Using the final weight alone inflates the apparent particulate mass.
Weigh the clean, conditioned filter before sampling (tare weight). After sampling, dry and condition the filter, then weigh it again. The mass is the difference: m = final weight – initial weight.
Common units:
- µg/m³ (micrograms per cubic metre).
- mg/m³ (milligrams per cubic metre).
- For PM2.5 and PM10, values are often reported in µg/m³.
Using a flow meter (e.g., rotameter, mass flow meter) calibrated to the sampler. The volume is the product of flow rate and sampling time. Volume is typically corrected to standard temperature and pressure (STP) for comparability.
PM2.5 refers to particles with aerodynamic diameter ≤ 2.5 µm (fine particles). PM10 refers to particles ≤ 10 µm (coarse and fine). They are sampled using different inlet designs (impactors) and have different health effects.
1 mg/m³ = 1000 µg/m³. To convert µg/m³ to mg/m³, divide by 1000.
The flow rate must be accurate and constant to ensure a representative sample. The sampler is calibrated to a specified flow rate (e.g., 16.7 L/min for PM2.5). Variations affect the volume and thus the concentration.
- Federal Reference Method (FRM) for PM2.5 using a filter and impactor.
- TEOM (tapered element oscillating microbalance) for continuous measurement.
- Beta attenuation monitors (BAM).
- Optical particle counters.
- Use certified reference filters.
- Conduct flow audits and calibrations.
- Check for leaks in the sampling system.
- Follow standard operating procedures (EPA methods).