When should respirator filters be changed?

Respirator filters should be changed based on the manufacturer's guidelines because these guidelines are specifically designed to ensure the filters are effective and safe for use. The manufacturer tests the filters under various conditions and provides recommendations on when to replace them based on factors like the type of contaminant, its concentration, and the duration of use. Adhering to these guidelines helps maintain the efficiency of the respiratory protection system, ensuring that the user is adequately protected from harmful airborne substances. Proper timeliness in changing filters is essential, as filters that are not changed according to the manufacturer's instructions could either compromise safety or lead to unnecessary costs.

The other options suggest criteria for replacement that may not align with the established safety standards. For instance, changing filters only when they are visibly dirty may not be sufficient, as contamination isn’t always visible. Changing filters at the end of every use or on a monthly basis might be excessive, especially if the filters are still effective, leading to increased costs and waste. Therefore, following the manufacturer's recommendations is the most appropriate and safe approach.