Introduction Exposure to organic dust is a well-known risk in the agro food sector. A transition from gravimetric analyses of dust to real-time direct reading equipment is taking place. The goal of this study is to explore the validity of using a low cost sensor, the Optical Particle Counter (OPC), for assessing occupational exposure to organic dust in the agrofood industry.

Methods In two onion processing companies particle number concentration (PNC) was continuously monitored for 7 days with 2 OPC devices, a TSI 3321 Aerodynamic particle sizer (APS), and a 3081 scanning mobility particle sizer (SMPS). Correlations between PNC as obtained by the different types of direct reading equipment were investigated for OPC versus OPC and for a combination of APS and SMPS vs OPC.

Results A high correlation between total PNC obtained by two OPC devices in both companies (r = 0.99 and r = 0.70) was observed. The observed correlation between total PNC obtained by combining the APS and SMPS and the two OPC devices was moderate (r = 0.58–0.62 and r = 0.35–0.48). A large variability in hourly correlations between APS/SMPS and OPC is observed. It is currently being explored if the correlation is affected by (variability in) the size distribution or total particle count.

Conclusions The preliminary results give some indication that low cost real-time sensors, like the OPC, may be used to monitor occupational exposure to particulate matter, providing the opportunity to obtain real time exposure data. Since endotoxin as components of organic dust is a major concern in the agrofood industry, the feasibility of using the OPC as the basis for an ‘online’ screening method for endotoxin is currently being explored in an experimental setup.