Particle Measuring Systems (PMS), founded in 1972, supplies contamination monitoring solutions for water, chemical, airborne and molecular applications within the microelectronics industry. The company has over 35 distributors, and local sales and services in more than 50 countries, making it the largest speciality particle counter manufacturer in the world. It supplies continuous particle monitoring, providing detection of particles >20nm in ultrapure water or chemicals, and >100nm particles in air and gas. PMS also provides services including monitoring systems software, training, data management and calibration.

PMS is part of Spectris, experts in precision measurement techniques for materials analysis. In 2023 Particle Measuring Systems announced the acquisition of EMS, the parent company of Environmental Monitoring Services Irl. Limited and EMS Particle Solutions Ltd. EMS provides complete cleanroom monitoring and control solutions and services.