How do you know if you are exposed to cancer-causing substances, and when or where this happens? New, low-cost sensors can help answer these questions. Researchers at TNO in the Netherlands are studying the use of sensors for different harmful substances, such as welding fumes, hardwood dust, and silica. They recently published a guideline called “Particulate Matter Sensors in the Workplace.”
Sander Ruiter, one of the researchers at TNO, explains why sensors are such a great tool to measure exposure to substances: “Traditional measurement systems use filters that collect dust or particles for a few hours or a whole working day. The samples are then sent to a laboratory for analysis, and you will receive the results a few weeks later. Sensors are easier to use and cheaper, since you do not need a laboratory. They can also measure in real time. For example, you can see if there was a peak in exposure at 11 o’clock for five minutes. With filters, you would only know the average exposure levels over the whole measurement period. With sensors, you get results immediately and can more easily trace back what a worker was doing at that moment.”
Sensors will definitely improve the options we have, for example allowing for implementing control measures the very moment exposures occur (called real-time risk-management). However, there are also some improvements possible. TNO’s research shows that sensors give consistent and correct results for measurements over time, but – like all measuring systems – they have some uncertainty (see figure below). This uncertainty is different for each substance. Sander explains: “At the moment, we are doing research on welding fumes. We want to know the exact uncertainty and calibrate the sensors for this substance, with the hope that the calibrated sensors can be used for compliance testing. Right now, one sensor cannot yet be used for many different substances.”
If you want to measure a specific substance accurately, the sensor can be calibrated for that substance. “This gives you a personal tool you can use whenever you want, in different areas of a company. This is a big advantage compared to the filter-based system, which is typically only used for about five measurements per year for the whole company, due to the large analysis costs. That is supposed to represent all workers, but it often does not.”
Guideline for Particulate Matter Sensors in the Workplace
TNO has published a guideline, available in English and Dutch, to help occupational hygienists use low-cost particulate matter (PM) sensors correctly. The guideline explains what PM sensors can and cannot do, how to choose a sensor, how to interpret the data, and how to implement the measurements.
