Allergy Environmental Control

by Dr. Christopher Chang, last modified on 5/21/21.

Introduction:

When a patient has bad allergies, not only are medications like nasal sprays and pills important, but also environmental control (where feasible) to minimize being exposed to things that cause allergy symptoms in the first place. Such environmental controls to improve air quality would also minimize the need for medications and make them work even better. Outside of a school or work environment, the home is where a patient may spend a great deal of time. The home is where one can easily take steps to improve the air quality and therefore reduce allergy symptoms.

The suggestions below are "general" steps to be taken for anyone with bad allergies. Steps that are specific for certain allergens are clarified.

Window Drapery and Carpets are a No-No

Window blinds are better than cloth drapes. Hardwood floors (or equivalent) are better than carpet. Drapery and carpets tend to attract and retain allergens. Routinely vacuum and clean all such surfaces.

HVAC Filters

Install good filters at ALL air intake ventilator grills. These air intake grills are typically found in a wall or ceiling and is where air goes IN. A good air filter would remove all particulates in the air over time that may cause allergy symptoms (ie, pollen, mold, dust, etc). Installing a good filter in this location (rather than at the air handler itself) also prevent the ducts and HVAC system itself from becoming dirty with dust and allergens over time.

Air filters are rated in how efficiently they perform this task using the MERV scale. MERV stands for Minimum Efficiency Reporting Value. MERV scales range from 1 to 16 with "1" being the least efficient and "16" describing the highest efficiency.

Obviously, avoid MERV 1 - 4 which does a poor job of removing allergen particulates.

MERV 5 - 13 is reasonably efficient in removing airborne allergen particulates.

As such, for patients with bad allergies, one should purchase air filters classified between MERV 13 - 16. These filters are expected to remove all allergen particulates at about 75% efficiency after a single pass. Before a patient gets all worried about 75% not being as good as 99%, keep in mind that in a home, air would pass through this filter multiple times. Such air recirculation would result in 75% of the particulates being removed from the air with each pass. After several hours, this would result in 99% particulate removal from the air. For those curious, HEPA filters have MERV ratings 17 - 20 which exceed 99% efficiency on a single pass, but honestly is probably not necessary for entire home use and can even potentially damage the air handler due to excessive strain (a lot more power is required to push air through). HEPA filters make more sense used in a portable unit for a single room (ie, bedroom).

3M uses a different rating system for some of their filters called MPR (Microparticle Performance Rating). MPR and MERV are basically the same thing. MPR 300 is equivalent to MERV 6; MPR 1000 = MERV 11; MPR 1500 - 2200 = MERV 12.

These filters can all be found and purchased on Amazon.

Change all air filters quarterly ideally and semi-annually at the very least. The filters WILL become dirty over time and not perform as well.

The key concept for clean air in the home using high MERV (or MPR) filters is "air recirculation". If you have a home's door or window constantly open, you are constantly bringing in NEW air along with allergens floating within. Close them!

For those paranoid about air quality, one can install multiple filters to the home's HVAC system. This basically means to install an air filter at the air intake grill, at the air handler unit, and where air comes out into a room. With such cascaded systems, you may need to hire a company to help in the install. However, a "simple" multi-filter system which I use in my home is to use a MERV 8 at the air intake grill and another MERV 8 in the air handler unit. Lower rated MERV filters can be used in such multi-filter systems and work as well as a single high MERV filter.

In a work situation, one can (try) and install a high MERV filter where air comes out into the room where you work. You may not have any power to change filters at the intake or air handler locations, but you might where air comes out. Obviously, you can keep windows/doors closed and purchase a portable HEPA unit for your own personal use.

Doors and Windows Closed!

Especially during bad allergy seasons, keep all windows and doors to the outside closed as much as possible to prevent allergens from the outside from coming in constantly. Otherwise, your HVAC filters are cleaning not just your home's air, but the air of the entire world coming in through your open windows and doors. (Your filters will lose.) Doing otherwise is defeating the purpose of the HVAC air filter which cleans the home air by air re-circulation.

With air re-circulation, one can achieve good air quality even with MERV 5 - 13.

This also means to keep the HVAC fan turned ON at ALL times (do not set to auto).

HEPA Air Filtration

Although HEPA filters can be added to the HVAC system, it requires professional installation given it would put too much electrical and mechanical strain on the fans. What would make more sense is to add a portable HEPA filter unit to a single room, typically the bedroom, to further ensure clean air beyond that provided by the home's HVAC system with high MERV filters.

Good portable HEPA units include those made by Dyson and Alen.

Personal Respirator Masks

If going outside during bad allergy seasons, consider wearing a personal respirator face mask. For example, if cutting the grass and you have severe grass allergies. Such masks can be purchased on Amazon and should be N95 or higher grade. Read more about allergy face masks here.

Mattress and Pillow Encasement (Dust and Dust Mite Allergies)

For allergies to dust and dust mite, completely enclose the mattress and pillow with an encasement. These critters LOVE hanging out and reproducing within the fabric eating human skin that has flaked off. Encasements suffocate dust mites and prevent them from populating where you sleep.

You can purchase such mattress and pillow encasements on Amazon.

For Those With Pet Allergies

If you own any pets, do not allow the pet in the bedroom ever. Regularly wash or vacuum the pelt, especially if the pet goes outside or under/around furniture since pollen and dust may accumulate on the fur.

Links

Allergy Environmental Control

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