A few decades ago an ISO standard emerged for airborne particulate counters used in the clean manufacturing industry. ISO 21501-4 was created in direct response to industry complaints regarding the lack of accuracy or repeatability that existed with the instruments available at that time. And, though this industry had managed with existing instruments for several decades, this standard was a watershed event that changed the particle counting for the industry. Within a short time of its adoption virtually every instrument sold to this industry was required to meet this standard. The greater indoor and outdoor air quality industries have been and continue to be without any real calibration standard for airborne particle counters. Some of the instrument vendors offer ISO 21501-4 compliant instruments to this industry, which is really the only viable solution at present, but it was never really designed for this industry and has some short-comings and weaknesses in addressing the specific requirements of indoor/outdoor air quality. Recently, Particles Plus has come up with a proposed standard for airborne particulate counters vis-a-vis the indoor/outdoor air quality industries. We started with ISO 21501-4 and adjusted and extended it to suit it more specifically to this industry. The intent being to create a standard that would ensure that instruments that comply with this standard would provide a common level of accuracy and repeatability. This presentation goes through this proposed standard outlining the similarities and variances to the ISO 21501-4 standard and detailing the expected benefits and showing the process on some real instruments that meet the standard and characterizing their performance.
