Source code and documentation for an embedded air quality sensor node based on
Raspberry Pi Zero and low-cost retail sensors. Measurements are made every 10
seconds and recorded to the SD card in tab-separated (TSV) files. Data are also
exported to temporary files for integration with RPi Monitor
and scp-based scraping tools (e.g. the Itron Cloud service agent).
- Environmental measurements
- Carbon dioxide (CO2) concentration (Senseair K30 Engine, sold by CO2meter.com)
- Particulate (aerosol) concentration (Alphasense OPC-N2)
- Ambient temperature & relative humidity (Adafruit HTU21DF breakout)
- Barometric pressure & ambient temperature (Adafruit BMP280 breakout)
- Supporting hardware
- Single-board computer (Raspberry Pi Zero)
- Real-time clock (Adafruit DS3231 breakout)
Also, a relevant excerpt from optical particle counter user manual:
"The accepted international standard definitions of particle mass loadings in the air are PM1, PM2.5 and PM10. These definitions relate to the mass and size of particles that would be inhaled by a typical adult. So, for example, PM2.5 is defined as ‘particles which pass through a size-selective inlet with a 50% efficiency cut-off at 2.5 μm aerodynamic diameter’. The 50% cut-off indicates that a proportion of particles of larger than 2.5 μm will be included in PM2.5, the proportion decreasing withincreasing particle size, in this case out to approximately 10 μm particles."
A few test data sets are available here. You can view example code in the Jupyter notebook "Validation Testing" directly in Github, or to see/interact with the Bokeh plots too, open locally with Jupyter or render it using nbviewer.jupyter.org.
- Bench test (Dec 4-5, 2016)
- Roof test #1 (Dec 5-6, 2016)
- Roof test #2 (Dec 14, 2016 - Jan 9, 2017)
This work licensed under The MIT License.
- Alphasense. Alphasense User Manual OPC-N2 Optical Particle Counter. Revision Apr 2015. Online: http://web.archive.org/web/20161203001923/http://staging1.unep.org/uneplive/media/docs/air_quality/aqm_document_v1/Blue%20Print/Components/Microcomputer%20and%20sensors/B.%20Dust%20Sensor%20Specifications/B.1%20Alphasense%20OPC%20N1/072-0300%20OPC-N2%20manual%20issue%203.pdf