Real-time monitoring of cleanroom laboratories using low cost sensors

An air filtration system (AFS) is necessary for laboratories that analyze trace components in natural or artificial samples liable to be contaminated by airborne particulates. In general, an AFS employs multi-stage air filters with a HEPA (high efficiency particulate air) or an ULPA (ultra-low penetration air) filter as the final filter to supply particle-free air to a laboratory. However, using these filters does not guarantee the desired cleanliness of air, and routine assessment of the particle levels in laboratory air is required especially given the potential increase in atmospheric fine particles in Korea. In this context, we have developed a real-time particle monitor (PaMo) using a low cost sensor module and a web based data logger. A temperature and humidity sensor was also included in the PaMo. Two PaMo units have been installed in two cleanroom laboratories for ice core research at the Korea Polar Research Institute. The number of particles larger than 0.3 mu m, temperature and relative humidity were monitored from 29th March to 24th June 2018. This real-time monitoring proved that, although the particle concentrations in the room air increased with that in the outdoor air, the AFSs were able to achieve and maintain the cleanliness required for each laboratory. The PaMo will be able to identify particle sources other than the outdoor air, provide a guideline for when to replace filters and notify unexpected AFS failure. We suggest that the PaMo is an easy and effective alternative to expensive particle counters for laboratories that operate AFS.