Making sense of low cost sensors. Air quality monitoring in Gothenburg Sweden
Typ
Examensarbete för masterexamen
Program
Industrial ecology (MPTSE), MSc
Publicerad
2020
Författare
Ghalebani, Mehdi
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Over the recent decade, Emergence and commercialization of the new, low-cost, sensor
technologies have created the possibility of major paradigm shifts in air quality
monitoring. Their price of three orders of magnitude lower than standard/reference
instruments provides the opportunity for new applications such as higher geographical
and temporal resolutions of the measurements. There have been studies on the
performance of a network of these sensors, however, their individual reliability is
still questionable. This study aimed to evaluate the performance of one of the most
common low-end sensors available on the market, SDS011, as well as a middle-end
sensor, SDS019 under different circumstances such as temperature and humidity.
The main research questions were: how reliable are these sensors and what are the
causes of errors for these sensors and is it possible to find correction factors based on
meteorological data? To address the research questions, a range of experiments in
different environments, including field and laboratory, have been conducted under
several humidity and temperatures. The results of the experiments illustrated a
high linear correlation between the SDS011 and SDS019 sensors with the reference
sensor(Optical Particle Sizer) at laboratory experiments. The data were fitted to the
reference sensor using a linear regression model. additionally, a multiple linear regression
was applied to include the temperature and relative humidity as additional
input parameters to the regression model. The results of the multiple and normal
regression were compared and discussed under different circumstances for both
SDS011 and SDS019 sensors. The field experiments showed significant differences
between the SDS011 and reference instruments and these could not be explained
by humidity alone. They were not significantly reduced when applying laboratory
correction factors either. A three week comparison of the SDS011 against the golden
standard for PM in air quality monitoring (TEOM) showed periods with both decent
and poor agreement, illustrating that the SDS011 sensors respond to PM but
that they are rather unreliable when used as single devices. Further research work
is needed to understand this. Nevertheless the sensors are suitable for operation in
a network to obtain spatial air quality information , both as stationary and mobile.
Beskrivning
Ämne/nyckelord
air quality monitoring, low-cost sensors , multiple linear regression, signal processing, aerosols , particulate matter , PM2.5, particles , dust, human health.