'Low-cost' pollution sensors - understanding the uncertainties
Low-cost sensors typically result in a trade off being made between the price,size and power consumption of the device and the accuracy and precision of the measurement being made. Sometimes the trade-off occurs because of issues associated with low-cost manufacturing, or it may be because the analytical chemistry method itself is more uncertain than reference methods. For example, many sensors are sensitive to changes in atmospheric humidity and temperature, or can give false signals if other air pollutants are present in high concentrations. This means that, at least for now, low-cost sensors cannot be used as direct replacements for the reference monitors used by Defra in the AURN. Additionally, most low-cost sensors have no form of on-going quality control or calibration applied to them once in the field, unlike reference measurements. However as the technology evolves applications will arise where they do bring new insight to air pollution issues.
It is essential that before any user decides to apply low-cost sensors to study air pollution that they consider in detail how accurate and stable those sensors are likely to be and whether this will be sufficient for the task at hand. The sections on ‘How do sensors perform compared to reference instruments?’ and ‘When could I use a low cost sensor?’ provide some useful information to help in this decision making.
A review article in the journal Nature from 2016 summarises the importance of understanding how sensors perform before they are put into practical use. The article is available for download here:
Validate personal air-pollution sensors AC Lewis and P Edwards, Nature, 535, 29-31, 2016.
Recent academic reviews on the potential use of sensors from a user perspective can be found in the articles:
End-User Perspective of Low-Cost Sensors for Outdoor Air Pollution Monitoring AC Rai et al. Science of the Total Environment, 607-608, 691-705. 2017.
Can Commercial Low-Cost Sensor Platforms Contribute to Air Quality Monitoring and Exposure Estimates? N Castell et al. Environment International. 99, 293-302. 2016.