Sources of error and variability in particulate matter sensor network measurements

Area of Science:

• Environmental Science
• Industrial Hygiene
• Sensor Technology

Background:

• Low-cost particulate matter sensors are increasingly used for air quality monitoring.
• Accurate conversion of sensor output to mass concentration requires robust calibration.
• Existing calibration methods may not fully account for real-world environmental factors.

Purpose of the Study:

• To evaluate temporal changes in sensor calibration.
• To assess spatial and temporal variability in gravimetric correction factors.
• To improve the accuracy of mass concentration estimates from sensor networks.

Main Methods:

• Deployed a 40-node sensor network in a manufacturing facility for 8 months.
• Conducted continuous monitoring with sensors and a photometer for calibration.
• Performed intensive sampling campaigns using gravimetric samplers and photometers for correction factors.

Main Results:

• Field-determined sensor calibration slopes and intercepts differed significantly from laboratory values.
• Sensor calibration slopes decreased and intercepts increased over time, indicating deterioration.
• Correction factors varied significantly between different occupational process areas.

Conclusions:

• Field calibration is vital for accurate conversion of sensor voltage to mass concentration.
• Sensor calibration requires periodic re-evaluation due to temporal drift.
• Location-specific gravimetric correction factors are necessary for precise industrial air quality assessments.