High-purity quartz (SiO2
) microfiber filters are used for air sampling in acidic gases, stacks, flues and aerosols, particularly at high temperatures up to 500 °C and in PM-10 testing
Technical Note PM10 Filters . Because of the low level of alkaline earth metals, ‘artifact’ products of sulfates and nitrates (from SO2
) are virtually eliminated. QM-A, sequentially numbered according to EPA standards, is suitable for most applications.