Austin researched this question extensively. They have not found that there is enough value added to the purifier or to the purifier users to justify the cost of adding such an indicator. To summarize our research:
- A simple timer could be used that would track the length of time the unit has been operating. A light would turn on after a given length of time. Some of our competitors provide this type of mechanism in their units. This is the least costly and least complicated indicator method. However, it doesn’t truly measure the life of the filter.
- An indicator which measures the pressure drop of the filter could be added. The higher the pressure drop, it is assumed the dirtier the filter. This indicator type is more costly than the first option. The issue with this type of indicator is that the carbon used in our filters is normally used up long before the pressure-drop level is reached. Thus, our filter would need to be replaced before the indicator light is activated.
- An indicator could be developed which measures the vapor phase pollution level of the air exiting the unit. This indicator type would be very costly to develop and it would unjustifiably burden the user of the unit.