Calibration and initial measurements with a low-cost and moderate-precision CO2 sensor

To better understand the variation of greenhouse gas levels, particularly in urban environments near areas of high fossil fuel emissions, more observations of these gases, such as carbon dioxide are required. Most scientific-grade trace gas analyzers cost thousands of dollars each, allowing for high accuracy (±0.1 ppm) but because of the price, limit the applications and locations of these instruments. With Senseair's K-30 platform, a NDIR CO2 measuring module, a small trade-off in accuracy is made for a device that is orders of magnitude less expensive. Running one of these K-30 sensors, alongside a Picarro cavity ringdown spectrometer, and later a Los Gatos Research GHG analyzer, the K-30 was found to be within ±5 ppm of the research grade instruments without any correction for temperature, pressure or relative humidity. Using a few of these instruments running in parallel, observations of the diurnal CO2 cycle were observed in suburban Washington, D.C. for a period of over six months. Additionally, the instruments were attached to cars as part of a three-day study of the CO2 dome over the Washington metro area.