Air Justice Lab

Air Justice Lab is a community air monitoring and educational initiative based at NATURE Lab and serving the greater Capital Region.

This repository archives historical air quality data (stored in the data directory) and scripts for archiving via the PurpleAir API (stored in the scripts directory.

Each day a GitHub Actions workflow runs node scripts/load.js to incrementally load historical sensor data and new data. And then the same workflow runs node scripts/index.js and node scripts/analyze.js to produce data/time-series.csv, visualized below.

Dependencies

• node.js v18
• PurpleAir API key

Developer Setup

1. Run npm install
2. Copy .env.example to .env and replace PURPLEAIR_API_KEY
3. Run npm start

Sensor list

The file data/sensors.csv has a list of Air Justice Lab affiliated PurpleAir sensors.

sensors.csv columns

1. id - PurpleAir sensor ID
2. name - the public sensor name
3. start - date/time of earliest records
4. end - date/time of most recent records

Records

Each sensor's historical records are stored in data/sensor-[id] folders. Batches of records are stored in files named sensor-[id]-[start timestamp]-[end timestamp].csv.

records columns

1. id - PurpleAir sensor ID
2. time_stamp - Unix epoch timestamp
3. pm2.5_alt_a - PM 2.5 ALT cf=3 channel A
4. pm2.5_alt_b - PM 2.5 ALT cf=3 channel B
5. pm2.5_atm_a - PM 2.5 ATM channel A
6. pm2.5_atm_b - PM 2.5 ATM channel B
7. pm2.5_cf_1_a - PM 2.5 CF1 channel A
8. pm2.5_cf_1_b - PM 2.5 CF1 channel B
9. temperature - degrees Fahrenheit
10. humidity - relative percentage humidity
11. pressure - pressure in Millibars

Time Series

Combined readings from all sensors over the last 7 days is available in data/time-series.csv.

time-series.csv columns

Sensor columns are sorted numerically by ID.

1. Time - date/time in ISO 8601 format (UTC timezone)
2. North Central Troy #1 (87173) - 10 minute averaged AQI readings
3. South Troy #2 (149970) - 10 minute averaged AQI readings
4. Rensselaer #6 (151502) - 10 minute averaged AQI readings
5. Cohoes (156051) - 10 minute averaged AQI readings
6. Cohoes #17 (156171) - 10 minute averaged AQI readings
7. Cohoes (164327) - 10 minute averaged AQI readings
8. Cohoes #15 (164351) - 10 minute averaged AQI readings
9. Rensselaer #10 (166327) - 10 minute averaged AQI readings
10. Lansingburgh #8 (166331) - 10 minute averaged AQI readings
11. Cohoes #14 (166371) - 10 minute averaged AQI readings
12. Stephentown #22 (166653) - 10 minute averaged AQI readings

Data Attribution

Source: PurpleAir

References

• Sensor map
• Sensors - Get Sensor History
• What is the Difference Between CF=1, ATM, and ALT?

Data Attribution

Source: PurpleAir