Which factor does NOT determine the life of an air filter?

The life of an air filter is influenced by several important factors that dictate how long a filter will effectively perform its task. Among these factors, outdoor air quality is not a determining element of the filter’s lifespan when considering how the specific filter itself is designed to operate within a controlled environment.

The type of media used in the filter significantly impacts its efficiency, dirt-holding capacity, and overall durability. Different media types can affect how many particles are captured and how quickly the filter becomes clogged.

Filter size and surface area also play critical roles; larger filters or those with greater surface area can capture more contaminants before needing replacement, thereby extending their life.

Additionally, the frequency of maintenance relates to how often filters are checked, cleaned, or replaced, which directly affects their functionality and lifespan.

Outdoor air quality can have a direct effect on the amount of pollutants that enter a building, hence influencing when maintenance might be necessary, but it does not affect the inherent capabilities or life expectancy of the filter itself under normal conditions. Therefore, among the options presented, outdoor air quality is the factor that does not determine the life of an air filter directly.