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6. Data Quality and Completeness

When assembling multi-year datasets from batch downloads, researchers should apply the following quality control practices recommended by AirQo:

6.1 Data Completeness Threshold​

AirQo recommends using only data from monitors that provide ≥50% of expected measurements for any given analysis period.

  • Hourly analysis — A monitor providing fewer than 12 readings in a 24-hour period should be flagged for that day.
  • Daily averages — Fewer than 72 measurements out of 144 expected means the daily average may not be representative.

6.2 Missing Data​

  • AirQo does not interpolate or backfill missing values. Missing readings remain null/empty.
  • This is intentional — air quality can change rapidly, making interpolated values unreliable for exposure assessment.
  • When combining quarterly files, verify that your analysis software handles null values correctly and does not silently treat them as zeroes.

6.3 Coordinate Approximation​

  • Monitor coordinates are offset by approximately 0.5 km from actual physical locations for privacy reasons.
  • This applies across all data access methods.
  • For research requiring exact coordinates, contact support@airqo.net.