Implementing Environmental Corrections to Increase the Accuracy of a Low-Cost 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) observations but because of the price, limit the applications and locations of these instruments. The Senseair K-30 is a small, low-cost NDIR CO2 sensor designed for industrial applications due to its manufacturer's provided accuracy of +- 30 parts per million (ppm). However, initial results running parallel with a research-grade greenhouse gas analyzer have shown that the absolute accuracy of the sensor is within +-5ppm, suggesting their utility for sensing ambient air variations in carbon dioxide. Through a multivariate analysis, we have determined a correction procedure that when accounting for environmental temperature, humidity, pressure, and the device's span and offset, we can increase the short-term accuracy of the K-30 to a value in the low single-digit ppm range.