During wildfire events, building managers often need to quickly adapt their air filtration systems to handle both smoke particles and odors. While standard air filters help with particulates, the unique challenges of wildfire smoke may require additional measures, particularly carbon filtration. These FAQs address the most common questions about modifying HVAC systems to better protect occupants during wildfire events.
Q. Can I install a carbon filter in my air handler temporarily until fires are contained?
A. Yes, depending upon your air filtration system, you may substitute or add a carbon filter on a temporary basis while air quality suffers due to wildfires. If you add a carbon filter, make sure that your system can accommodate the reduced airflow stemming from an additional filter.
Q. Should I remove my current prefilter and install a carbon pleated filter to reduce the smokefrom wildfires in my facility?
A. Yes, if your air filtration system permits, you can substitute a carbon filter for your prefilter to reduce odors caused by wildfires. When possible, use a carbon filter with a MERV rating, so you don’t sacrifice particle filtration.
Q. If I have a two-stage air filtration system with MERV 8 prefilters and MERV 14 final filters,where do I install a carbon filter?
A. Ideally, carbon filters would be added as an additional stage of filtration between two particulate filters. If you add a carbon filter, make sure that your system can accommodate the reduced airflow stemming from an additional filter. If that is not possible, then we recommend substituting a filter with carbon media for your current prefilter, leaving the higher-efficiency filter in place to reduce levels of fine particulate. If you are not able to substitute a carbon filter for your prefilter, then you can substitute a box-style carbon filter for your final filter.
Q. What MERV rating are carbon filters?
A. Because carbon filters are designed to reduce odors rather than particulates, they may not have a MERV rating. Generally, however, these filters are rated MERV 6-8.
Q. Are there different blends of carbon for specific odor removal?
A. Yes, there are many different blends of carbon. For wildfires, we recommend filters with carbon media, which help to control smoke odors and ozone, as well as pet smells, tobacco smoke, food odors, and mustiness.
Q. What else can I do to reduce risks to my health in the event a wildfire occurs nearby?
A. Along with installing filters rated MERV 13 or higher, the EPA also recommends closing fresh air intakes and recirculating indoor air where possible to reduce smoke entering the building. Other suggestions include keeping all windows and doors closed and scheduling a review of your HVAC system by a trained professional to ensure there are no gaps or leaks. If you must be outdoors, wear an N95 mask if possible.
Q. How often should I replace carbon filters?
A. The answer depends on many factors, including the concentration levels of contaminants and volume of airflow. Inodor control applications, you should change the filter when the odor becomes noticeable again, taking note of the length of time that the carbon filter was in place. Also, monitor the pressure drop from upstream of the combination of filters to downstream: if odors do not return, change the carbon filter when differential pressure reaches 2-3X theinitial/clean pressure drop.
Q. What is the difference between activated carbon and impregnated carbon?
A. Activated carbon, also known as virgin activated carbon, is the most common type of carbon used in gas-phase filtration. It removes volatile organic compounds (VOCs), ozone, hydrocarbons, and nuisance odors via physical adsorption.
Impregnated carbon is a chemically treated virgin activated carbon that also removes acid gases such as formaldehyde and ammonia, via chemisorption. Without this chemical treatment, virgin activated carbon cannot remove these additional contaminants.
As a global leader in air filtration solutions, American Air Filter has the expertise and products to help protect your facility during wildfire events. Contact an AAF representative to discuss the best filtration strategy for your facility needs.
