The toxic facts are that indoor air can be 2 to 5 times more polluted than outdoor air.(EPA) Cheap, defective and dirty heating and air conditioning system (HVAC) filters are a poor line of defense against harmful airborne pathogens and debris. They are also the perfect breeding grounds for mold.

For example, a cheap or dirty filter acts like a sponge for water and condensation. It takes only 24-48 hours for mold to start growing on it and when you turn on your HVAC system, the spores can then flow all throughout your property contaminating every room and all your furniture. This can create what is called “sick building syndrome,” which can lead to a serious mold illness and or fungal infection for the occupants.

A dirty and clogged filter can also lead to reduced or no air flow at all. The result will be higher energy bills and can lead to your whole HVAC system needing expensive repairs or to be replaced. Hence, the wrong or dirty filter can cost you thousands of dollars and even you and your family’s health. Therefore, it is imperative that you learn how they work, the best ones to buy for your home and how to maintain them properly.

For people who suffer from a mold illness, the goal is to limit the spores in the air, thus limiting your exposure and the ability of the mold to reproduce and contaminate your home. One of your best lines of defense against airborne mold in your home is having the right HVAC filter and changing it often.

If you are looking to improve your overall indoor air quality of your home, most of the standard cheap HVAC filters that you can find at the local Walmart simply won’t do the job. That is why having a highly efficient disposable filter is paramount if you want to reduce your exposure to harmful debris, dust, pollen and microorganisms such as toxic molds.

How filters work is simply by dirty air passing through the filter in order to catch the various debris and microorganisms which then releases the filtered clean air. The key in getting the right filter is to make sure that it will clean most of the air contaminants in your home so you can breathe fresh air.  This is done by making sure that it can capture the tiniest of microbes such as mold spores which are measured at the very smallest, 1-3 microns and can easily be removed by using a good filter.

Minimum efficiency reporting value, commonly known as MERV rating, is a measurement scale designed in 1987 by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of air filters. The higher the MERV rating equates to less airborne contaminants that can pass through the filter and cleaner indoor air.(Wikipedia)

The rule of thumb is the higher you go up the MERV scale, the better.

A really good filter with a MERV rating from 8-13 will capture 30 times or more pet dander, mold, and pollen than a standard filter which makes it much easier for people to breathe, especially those with allergies.

For example, one of the most common indoor molds that we find is aspergillus which has a particle diameter of 3.5 microns. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) says a MERV 6 filter can remove it when matched with a proper number of air changes.

Bacteria, droplet nuclei (sneeze), cooking oil, most smoke and insecticide dust, most face powder, most paint pigments will have a micron size of 1-.3 so you would need a filter with a rating of a MERV 13-16 to properly filter the air against these contaminants.

Here is a list of several different types of molds and their size along with the MERV rating from Camfil, a manufacturer of high efficient filters for commercial HAVC systems.

What type of filter should you buy for your property?

There are many types of filters on the market. Some good, some great and some are just terrible. When you search for good filter, you need to find one that has as a rating per the Occupational Safety and Health Administration (OSHA) minimum requirements with an efficiency of 50 to 60% or a rating of MERV 8, as determined by Test Standard 52.2 of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, may be appropriate.

(OSHA) recommends:

“High-quality filters must be used in a HVAC system during remediation because conventional HVAC filters are typically not effective in filtering particles the size of mold spores. Consult an engineer for the appropriate filter efficiency for your specific HVAC system, and consider upgrading your filters if necessary. A filter with a minimum efficiency of 50 to 60% or a rating of MERV 8, as determined by Test Standard 52.2 of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, may be appropriate.

Remember to change filters as appropriate, especially following any remediation activities. Remove filters in a manner that minimizes the reentry of mold and other toxic substances into the workplace. Under certain circumstances, it may be necessary to wear appropriate PPE while performing this task.”

This is what the Environmental Protection Agency (EPA) says:

“Air filters should have a dust-spot rating between 35% and 80% or a Minimum Efficiency Rating Value (MERV) of between 8 and 13. The higher the rating, the better the protection for the equipment and the occupants. It has been estimated that a 30% increase in static pressure across a coil results in a $200 per 10,000 cfm of air movement (at 7 cents per KWH). This does not include the added cost of cleaning dirty heating or cooling oils, drain pans, or air ducts.

Designers should consider specifying a low efficiency (~10%) pre-filter upstream of the main filters. The pre-filters are generally easy and inexpensive to change and will capture a significant amount of the particulate mass in the air thereby extending the useful life of the more expensive main filters.”

Mold Safe Solutions Conclusion

Please keep in mind that this is not a complete cure to keeping your indoor air clean, but one of the most effective tools for the defense against harmful pathogens and to create clean air in your home. One last note, even though these are great filters, you will still need to change them at minimum 3-4 times a year and if you have severe allergies or a mold problem, I recommend once a month or every other month.

To do so, I recommend that you wear safety equipment such as a HEPA mask and you install a vapor barrier around the area of at the very least, you use a HEPA vacuum and air filter right next to you so it will clean any dust that gets airborne.

You will need to measure the size of your filter and the easiest way to do that is by finding the size of the one that is currently installed and in use. If it is not listed on the current filter, take it out and measure the length, width, and depth and then round the numbers up to the nearest inch. It is better for it to be a little too large than too small so there are no gaps where debris and pathogens such as molds can bypass the system.

When buying a new filter, I recommend that you go as high as possible to a MERV rating of 13.

Here is a list below of some of the best and top rated air filters available that I could find on Amazon. Just make sure you get the right size. They are listed from the largest to the smallest. By shopping through our affiliate links, it costs you nothing extra and you will help to support our work.

For example, this is the AFB Platinum with a MERV 13. The size is 20x25x1 Pleated AC Furnace Air Filter. It comes in a pack of 6 Filters and is made in the USA.

AFB Platinum MERV 13 28x30x2 Pleated AC Furnace Air Filter. Pack of 6 Filters. 100% produced in the USA.

AFB Platinum MERV 13 16x30x1 Pleated AC Furnace Air Filter. Pack of 4 Filters. 100% produced in the USA.

US Home Filter SC80-20X30X2 20x30x2 Merv 13 Pleated Air Filter (6-Pack), 20″ x 30″ x 2″

US Home Filter SC80-20X25X2 20x25x2 Merv 13 Pleated Air Filter (6-Pack), 20″ x 25″ x 2″

AIRx HEALTH 20x20x1 MERV 13 Pleated Air Filter – Made in the USA – Box of 6

Lennox X0585 20x20x5 MERV 13 Comparable Air Filter – 2PK

Nordic Pure 16x20x1M13-6 16x20x1 MERV 13 Pleated AC Furnace Air Filter, Box of 6, 1-Inch

Nordic Pure 14x14x1M13-6 14x14x1 MERV 13 Pleated AC Furnace Air Filter, Box of 6, 1-Inch

Nordic Pure 14x20x1M13-6 14x20x1 MERV 13 Pleated AC Furnace Air Filter, Box of 6, 1-Inch