Warning: you will see Mestel Safety masks & filters on eBay marked as 'CBRN' - these filters do not have radiological protection according to European 'CE' Standards (similar to NIOSH standards in the USA).
This standard NATO-threaded filter made by Mestel Safety features a broad spectrum of protection against common organic and inorganic gas/vapors, Sulphur Dioxide, Ammonia and its derivatives. This filter is used for countless applications but is specifically designed for law enforcement/EMS applications.
'P3' particulate filter
In addition to the chemical protections, it features a P3-rated particulate filter that filters 99.95% of airborne particles such as:
'P3' only being achieved with full-face respirators like this one, it makes the Mestel family of products a fantastic choice to prepare for a large majority of scenarios the average civilian may face (civil unrest, natural disasters, industrial accidents, forest fires)
For specific information about chemical exposure times and gasses, we'll leave the details to Mestel. You can view the full technical sheet here.
In short, this multi-purpose filter is going to do pretty much everything you'd want when it comes to protecting your raspatory system & eyes from dangerous chemicals and inhalants — once again, contrary to some shady eBay listings, these are not specialty radiological filters (which in CE standards would have a magenta-colored stripe).
Re-usability & How to recognize end of service life
The end of this filter's service life is generally recognizable by a noticeable taste or smell of the contaminant, an increased breathing resistance and combination of the two - a variety of factors can change how long this filter lasts, including breathing rate of the user, temperature, air humidity, and contaminant concentration.
The user should replace the filter when they begin to perceive the smell or taste of the dangerous substance or in case of irritation, or when respiratory resistance becomes too high.
These filters are marked 'R' for reusable, meaning they can continue to be used at their rating until the end of their service life (as noted above).
CE Rating Notes:
You may notice the lack of "CBRN Approved" or "NIOSH Approved" because Mestel is out of Italy. The CE standards are slightly different in that products can be CE rated on their own (i.e., the respirator and filters separately) to speed up the process of being approved. This means if you combine a CE rated respirator (while keeping in mind the class of protection it provides) with a CE rated filter, you have a CE-rated system to the combined specs of the respirator and filter.
European Bureaucracy, right?
The letter system is easier to understand as far as filters go by consulting the below chart, and the numbers after each letter simply inform the level of 'capacity' to handle different concentrations of chemicals:
Specs