Your HEPA air cleaner is only as good as the HEPA replacement filter

Reluctant to buy that expensive replacement HEPA filter?
Very understandable, but because filters slowly get clogged with the very stuff that they are filtering, they become less efficient over time.
And that means that the fan will have to work harder, adding to the energy bill, and that the filter might start to re-emit trapped pollutants!

Good reasons for us to stick to the manufacturer’s guidelines and to purchase a HEPA replacement filter in time, even if they are not a cheap item.
However, not only HEPA replacement filters have to be exchanged from time to time. Here is a quick rundown of the type of filters that are around.

Types of air filter:

1. Prefilters are the least expensive, and they have been designed to absorb particles that are larger than 1 micron, thereby delaying the purchase of a far more expensive replacement HEPA filter.

2. HEPA filters are widely used, and are made of submicronic glass fibers in a thickness and texture very similar to blotter paper. They are expensive and quite fragile, so be careful when putting in a HEPA replacement filter. Unfortunately a replacement HEPA filter will not eliminate any odors, viruses and most bacteria, because these are smaller than 0.3 micron. That’s why a HEPA air purifier may also have:

3. An activated carbon filter, which has submicroscopic pores that allow it to filter odors, viruses and smaller bacteria. Similar filters can be made from an alumino-silicate crystal structure known as “zeolite", which has uniformly sized pores throughout its crystal structure. This material is more resistant to humidity than activated carbon, and lasts longer, but is not as effective. Often the two materials are combined. As it’s impossible to see whether the filter is due for replacement, it’s important to stick to the manufacturer’s schedule, and get a replacement filter in time.

4. The final type, the electrostatic filter, has a positively charged filter that collects the particles. It is quite effective on it's own, but can also act as a prefilter. No replacement filter is necessary, but it has to be cleaned regularly otherwise it looses it's effectiveness.