Abstract. Measurement and source apportionment of atmospheric pollutants are crucial
for the assessment of air quality and the implementation of policies for their
improvement. In most cases, such measurements use expensive regulatory-grade
instruments, which makes it difficult to achieve wide spatial coverage.
Low-cost sensors may provide a more affordable alternative, but their
capability and reliability in separating distinct sources of particles have
not been tested extensively yet. The present study examines the ability of a
low-cost optical particle counter (OPC) to identify the sources of particles
and conditions that affect particle concentrations at an urban background
site in Birmingham, UK. To help evaluate the results, the same analysis is
performed on data from a regulatory-grade instrument (SMPS, scanning mobility particle sizer) and compared to
the outcomes from the OPC analysis. The analysis of the low-cost sensor data
manages to separate periods and atmospheric conditions according to the
level of pollution at the site. It also successfully identifies a number of
sources for the observed particles, which were also identified using the
regulatory-grade instruments. The low-cost sensor, due to the particle size
range measured (0.35 to 40 µm), performed rather well in
differentiating sources of particles with sizes greater than 1 µm,
though its ability to distinguish their diurnal variation, as well as to
separate sources of smaller particles, at the site was limited. The current
level of source identification demonstrated makes the technique useful for
background site studies, where larger particles with smaller temporal
variations are of significant importance. This study highlights the current
capability of low-cost sensors in source identification and differentiation
using clustering approaches. Future directions towards particulate matter
source apportionment using low-cost OPCs are highlighted.