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Millipore filters were among the first to be used for ambient air monitoring, as early as the 1970s. Particulates and contaminants in the air affect human capital, the most precious natural resource our planet supports. Recognizing the need to protect this resource, industries, governments, and associated regulatory agencies around the world monitor ambient air. Air monitoring methods have been developed to detect and quantify diverse contaminants and particulates, including PM2.5, PM10, sulfur dioxide, fluorides, heavy metals, and radioactive particles. Many of these methods involve gravimetric analysis and monitoring systems that use membrane filter discs and filter holders.
Millipore filters, now supplied by Merck, are used in regulated ambient air monitoring methods. Use the selector wizard below to determine the correct filter to use for your air monitoring needs, or follow these links to the application of your choice:
Nuclear power is relatively clean and renewable, and through radiation monitoring, can be a safe source of energy for the planet. Although there are many naturally occurring radioisotopes that make up water, air, soil and organisms, the challenge in radiation monitoring is to detect the “non-natural” radiation signal above the naturally occurring background radiation levels. To support efficient, convenient radiation monitoring, Merck has developed a special Fluoropore™ membrane filter designed for alpha particle collection in continuous air monitors.
The Fluoropore™ filter for alpha particle monitoring provides:
Improved data collection: Unlike fibrous filter media that trap particles in their matrix, Fluoropore™ (hydrophobic PTFE) membranes collect particles on their surface. This surface collection provides better detection efficiencies and improved resolution.
Choice of pore sizes: Fluoropore™ membranes are available in 3 and 5 μm pore sizes. The smaller pore size provides high resolution. The larger pore size has very low pressure drop and greater throughput capacity, which minimizes the number of filter changeouts.
Contrasting backing material: The 5 μm Fluoropore™ membrane is bonded to a contrasting backing made from high density polyethylene fiber. The contrast between the top and bottom of the filter prevents incorrect installation in sampling devices. The backing also reduces the electrostatic charge of the filters and makes them easier to handle.
Recently, the focus has been on PM2.5 levels, which have been linked to respiratory problems, cancer, and aging-related disorders such as Alzheimer’s disease and bone damage. Major regulatory agencies have now issued guidance and methods for monitoring PM2.5, as outlined in the table below:
Merck Catalog No.
US, Japan US EPA 40 CFR part 50
46.2 mm ±0.25 mm
PTFE with a ring (For reference / manual method)
Glass fiber roll for automated / equivalent methods
Merck Ensures That Membrane Discs Match Regulatory Specifications.
Certification documents for each product will be shipped in each box. Detailed test results can be obtained by contacting Merck Technical Support.
AP20 Glass Fiber
AQFA Quartz Fiber
PTFE Filter with Ring
≤20 µg/filter disc
Loose Particle Test
≤20 µg/filter disc
≤3 kPa @ 0.45 m/s air flow rate
Additional tests performed for certified PTFE filters as per U.S. EPA guidelines**
≤25 µeq/g filter
Low background signal
*(As Per Chinese PM2.5 Sampling Standard) **Certification documents for each product, stating that all tests were carried out according to United States Environmental Protection Agency (EPA) requirements, will be shipped in each box.
PM 2.5 Membrane Characteristics and Detailed Test Specifications
Airborne particles in the range of 10 µm in size have also been linked to negative effects on our breathing and respiratory systems. Merck provides filter media designed for PM10 testing that complies with government-established standards.