Airfilters; a necessity of  modern life?

Jacob Schor, ND, FABNO


September 16, 2015



Clean Air


Those of us who live in urban areas and those of us who live in rural area and can smell the lovely aroma of wood smoke have something in common.  We all should be using air filtration systems in our homes to clean up the air we breathe.


I started paying attention to the research coming out on fine particulat air pollutants last winter after attending a conference in Florida on Environmental Medicine. I reviewed that conference both for the Natural Medicine Journal and the Townsend Letter.  The Natural Medicine Journal  on my urging is preparing a special issue focused on environmental medicine  that will come out soon.


Walter Crinnion, the Florida conference organizer, has written an excellent review for the journal on air pollution and its effects on health and disease.


What I learned in Florida about the effects of fine particulate air pollution has led to my writing or collaborating on several articles for the journal.


In the current issue I review a study by MC Power et al that found a significant association between exposure to fine particulates in the air and anxiety levels in women.  [1]


Julianne Forbes, a colleague who practices in Bridgeton, Maine, and I, (Julianne was my room mate in Florida) worked together on two pieces.  One that reviewed the Italian research by Solimini et al that found a strong link between airborne particulate levels and diabetes, well actually hospitalizations of diabetics.  Bad air days are bad news if you have diabetes.  [2]



Dr. Forbes and I have just finished reviewing a second study, this one on the benefits of using in home air filtration to reduce levels of air pollution and the resulting impact on blood markers used to measure risk of cardiovascular disease.  I’ll sumarize our article below but before I do, I want to mention something I did today.


All this thinking about fine particulates and all the nasty things they apparently do inside of us has made it difficult to breath at the office.  Our office front door at the office is separated from Parker Road by a low brick wall; the intersection of Parker and Mississippi is a stone’s throw away.  If anyone should be worrying about exposure to fine particulates, it is yours truly.


Thus this morning I impulsively purchased an additional air filter for our office.  We’ve been running an old Honeywell unit I purchased from Costco years ago.  With all this focus an my growing paranoia, I decided to step up the game, so to speak.  On the recommendation of the Dr. Tina Kaczor, Senior Medical Editor at the journal, I purchased a filter from a company named E.L. Foust that has apparently been making and selling air filters since 1974.  Dr Kaczor tells me that she has been referring patients to this company for many years.  What intrigues both of us about these filters is they allow a great deal of customization as to what the filter will remove from the air.  One can choose between nine different filtering materials, from your standard coconut shell charcoal to bituminous coal and even order custom mixes of materials.  One can even puchase bulk filter material and refill the filtering cartridge oneself, something that appeals to this do-everything-yourself sort of person.


When I spoke with their sales rep, Sue Reed, on the phone this morning she explained that they have a referral program.  If you tell them that I sent you, that is, you were referred by Dr. Jacob Schor, they will knock 20% off the price of their filters for you.  Funny, now that I think about it, there doesn’t seem to be anything in this deal for me.  Our new filter should arrive next week, so if this interests you, come check it out.  I ordered the model 160 R-2 room air purifier with their ‘standard mix’ of filtration material with an added HEPA filter to remove even the tiniest particulates.




So back to these new studies.  The study that Julianne and I just finished writing up was done by Majid Kajbafzadeh and colleagues at the University of British Columbia and it looked at both traffic related and woodsmoke particulates on measures of cardiovascular health and the effect putting a good HEPA air filter in people’s homes had. [3]  


The researchers enrolled  83 healthy adults  between the ages of 19 and 72 from 44 homes in traffic-impacted or woodsmoke-impacted areas of metro Vancouver, British Columbia. Of those 83 people, 29 were living in areas of high woodsmoke and 54 in areas of high traffic related pollution. High efficiency particulate air (HEPA) filtration systems were put in the homes.  The filters had both a ‘real’ setting and a ‘placebo’ setting.


Concentrations of  PM2.5 (the tiniest and most harmful sized air particles) were measured during two consecutive 7-day periods, one with filtration and the other with 'placebo filtration'.  Endothelial function and biomarkers of systematic inflammation (C reactive protein, interleukin-6 and band cells) were measured at the end of each 7-day period.


Using the HEPA air filters  lowered indoor PM2.5 concentrations by 40%. PM2.5 dropped 36% in traffic related polution area homes and 48% in homes with PM2.5 from wood smoke.


There was no significant relationship between PM2.5 exposure and endothelial function during the short period of the study but among male participants in high traffic related air pollution areas, there was a 20.6% increase in CRP levels per unit median increase in PM2.5 (95% CI 2.62%-41.7%) while in women there was no significant evidence of an association. A ‘unit’ is 10 mcg/ cubic meter of PM2.5/


There was evidence of a significant association between indoor PM2.5 and C-reactive protein among those in traffic-impacted locations (42.1% increase in C reactive protein per IQR increase in indoor PM2.5, 95% CI 1.2% to 99.5%), but not among those in woodsmoke-impacted locations. There were no significant associations with interleukin-6 or band cells.  There were what we would call trends in the data, but some people on this mailing list will point out that data that is ‘statistically non-signicant’ shouldn’t be mentioned.  Until we reach that threshold, what looks like an association between two things could just be a coincidence.




This is important; something as simple as a HEPA air filter in a matter of days can reduce exposure to fine particulates by half and with that reduce systemic inflammation from traffic related air polllution. 


Three other related papers have been published so far this year.  A June 2015 study of Chinese college dormitory students found that air purification resulted in a 57% reduction in PM2.5 concentration, from 96.2 to 41.3 μg/m3, within hours of operation and this was significantly associated with decreases in several circulating inflammatory and thrombogenic biomarkers. [4]   Recall that in Majid’s study a “unit” reduction was associated with about a 20% change in c-reactive protein.  Air filters in these Chinese dorms dropped PM2.5 by over five units!


A March 2015 study in Los Angeles of a HEPA air cleaning system for school buses cabin air for reducing children's exposure inside school buses reported that air filters are effective at reducing exposure. In this study biomarkers were not tested  but in-cabin ultrafine particles and black carbon levels were reduced by 88% and 84% respectively. [5]   A February 2015 study of home air filtration effect on 48 elderly people suggested that outdoor particle concentrations have adverse effects on microvascular function (MVF), and outdoor and indoor PM2.5 and bio-aerosols are associated with markers of inflammation and lung cell integrity. [6] 


A fourth study on air filtration published  in 2014  looked at the effect of indoor home air filtration  in 31 homes in Smithers, BC during the winter of 2009-2010.  Air filtration reduced PM2.5 by 52%. [7]


It is interesting to note that the air in schools and public buildings, because of their commercial HVAC systems is often cleaner than the air found in residential homes. [8] 


Fine particulate air pollution is considered a significant contributor to cardiovascular disease with small particles having a greater effect.  Emergency room hospitalizations have been correlated with fluctuating outdoor levels of PM2.5. [9] 


Our current approach for dealing with the health burdens caused by environmental factors is often to focus on diet and to suggest supplements that reduce inflammatory reactions caused by these exposures.


People rarely think of using air filtration to improve these markers or reduce acute cardiovascular risk in specific situations of ongoing daily or acute exposure where residential woodsmoke and traffic related environments are the norm. In the past we thought air filters were for people with allergies.  Now we need to think about them for people with systemic inflammation, anxiety, cardiovascular disease, and a host of other problems. 


For many people using an air filtration system to reduce exposure to PM2.5 may be the simplest way to make a difference in both overall health outcomes and to reduce risk of acute reactions to higher than normal air pollution days.  An unlike drugs or even nutritional supplements, we are not expecting to see any side effects.







1. Power MC, Kioumourtzoglou MA, Hart JE, Okereke OI, Laden F, Weisskopf MG. The relation between past exposure to fine particulate air pollution and prevalent anxiety: observational cohort study. BMJ. 2015 Mar 24;350:h1111.


2.   Solimini AG, D’Addario M, Villari P. Ecological correlation between diabetes hospitalizations and fine particulate matter in Italian provinces. BMC Public Health. 2015;15(1):708.


3.  Kajbafzadeh M, Brauer M, Karlen B, Carlsten C, van Eeden S, Allen RW. The impacts of traffic-related and woodsmoke particulate matter on measures of cardiovascular health: a HEPA filter intervention study.Occup Environ Med. 2015 Jun;72(6):394-400. doi: 10.1136/oemed-2014-102696. Epub 2015 Apr 20.


4.  Chen R, Zhao A, Chen H, Zhao Z, Cai J, Wang C, Yang C, et al. Cardiopulmonary benefits of reducing indoor particles of outdoor origin: a randomized, double-blind crossover trial of air purifiers. J Am Coll Cardiol. 2015 Jun 2;65(21):2279-87.


5.  Lee ES, Fung CC, Zhu Y. Evaluation of a high efficiency cabin air (HECA) filtration system for reducing particulate pollutants inside school buses. 2015 Mar 2. Environ Sci Technol. 2015 Mar 17;49(6):3358-65.


6.   Karottki DG, Spilak M, Frederiksen M, Jovanovic Andersen Z, Madsen AM, Ketzel M, et al. Indoor and outdoor exposure to ultrafine, fine and microbiologicallyderived particulate matter related to cardiovascular and respiratory effectsin a panel of elderly urban citizens. Int J Environ Res Public Health. 2015 Feb 2;12(2):1667-86.

 Free PMC Article


7.  Wheeler AJ, Gibson MD, MacNeill M, Ward TJ, Wallace LA, Kuchta J, Seaboyer M, et al. Impacts of air cleaners on indoor air quality in residences impacted by wood smoke. Environ Sci Technol. 2014 Oct 21;48(20):12157-63.


8.  Chan WR, Parthasarathy S, Fisk WJ, McKone TE. Estimated effect of ventilation and filtration on chronic health risks in U.S. offices, schools, and retail stores. Indoor Air. 2015 Jan 30.


9.  Franck U, Odeh S, Wiedensohler A, Wehner B, Herbarth O. The effect of particle size on cardiovascular disorders—The smaller the worse. Sci. Total Environ. 2011;409:4217–4221.