Why Carpeting is Healthier For Your Home Than Smooth Surfaced Flooring

Enviroclean of Illinois
Jan 26
10 min read

The dynamics of indoor microscopic biological contaminates and their impact as a variable Particulate Matter upon carpeted surfaces and hardwood flooring.

This is the NERD

in me.

There are multiple sources and scientific analyses providing evidence indicating that carpeting and hard surfaced flooring can both improve and harm the air quality of the indoor environments in which they are found. After having read through dozens of research papers, I have found several commonalities which appear to indicate that a vast majority of the research is designed to address the various types of VOC'S, SVOC's, and airborne particulate matter (aka PM), however, nearly all studies exclude the biological contaminates that are also present within indoor environments. Additionally, the majority of the studies indicate that cleaning can potentially improve and exacerbate the indoor air quality. The key is whether the cleaning event has been performed correctly. Below you will find brief excerpts from various studies with citations given when I could find them. I apologize if I've missed any references.

First, it is important to have a basic visualization of the size, composition, and quantity of the issues to be addressed. Generally, the composition of the microscopic contaminates within our enclosed indoor environments (homes, offices) is:

House dust, which is a mix of sloughed-off skin cells, hair, clothing fibers, bacteria, dust mites, bits of dead bugs, soil particles, pollen, mold spores, and microscopic specks of plastic

Other environmental contaminants can be tracked indoors on the soles of our shoes. So in addition to fluffy hair and garden dirt, dust can hold a witch’s brew of persistent organic pollutants, metals, endocrine disruptors, and more.

[People add to the dust’s organic load as their warm bodies volatilize deodorant or fragrance compounds from personal care products. “Our skin cells and clothing fibers may also accumulate chemicals from the air before they are then shed to dust, where they can accumulate yet more chemical]¹

It is understood that (Arizona Test Dust) ATD is not coated with residual oils or the common contaminates as would be found in most house dust, nor does it contain other biological particles and allergens that may affect particle resuspension²

¹ See http://www.nationalacademies.org/hmd/Activities/PublicHealth/Health-Risks-IndoorExposure-ParticulateMatter/2016-FEB-10.aspx (accessed July 28, 2016).

² -Resuspension of Particulate Matter from Carpet Due to Human Activity Jacky A. Rosati , Jonathan Thornburg & Charles Rodes To cite this article: Jacky A. Rosati , Jonathan Thornburg & Charles Rodes (2008) Resuspension of Particulate Matter from Carpet Due to Human Activity, Aerosol Science and Technology, 42:6, 472-482, DOI: 10.1080/02786820802187069 To link to this article: https://doi.org/10.1080/02786820802187069 Published online: 17 Jun 2008.

Chart

Volume 95 Issue 7 | pp. 18-21Issue Date: February 13, 2017 | Web Date: February 7, 2017

Tracing the chemistry of household dust

Researchers are finding an ever-growing list of chemicals in dust and are trying to understand what the compounds mean for our health

By Janet Pelley

Upon reviewing each of the many studies involving re-suspension of particulate matter within an indoor environment, there appears to be one reoccurring theme, that is the majority of the studies employ Arizona Test Dust (ATD) as the dust sample to determine the translocation and resuspension activities of dust within a home. ATD is convenient because it is a consistent mix of many of the impurities found within carpeting with [too many exceptions including: biological contaminates, typical household oils, mold, pollen, fungi spores that are always found within homes in mass volumes]. The studies tend to concentrate on the volume of PM produced from the material composition of the flooring itself, and the re-suspended volumes of ATD in the air and their decay (gravity drop) durations prior to returning to pre-disturbed values. Each of the studies tended to indicate that hard surfaced flooring such as vinyl or wooden flooring did not re-suspend as much volume of PM as readily as carpeting did, however, the experiments did not include the biological impurities within the studies on either the hard surfaced flooring or the test carpeting. Therefore, the results of these tests are inconclusive at best without including the biological composition commonly found within indoor environments.

Potential Benefits of Carpeting on Dust Control - A few research studies have shown that airborne dust levels can actually be lower in carpeted rooms as compared to non-carpeted rooms. This unusual finding has been observed in situations where the carpet has been maintained with an aggressive vacuuming schedule. One such study compared airborne dust levels in classrooms and found lower levels in carpeted rooms even after heavy foot traffic, which would be expected to transfer particulates from carpet into air.16 This reduction may be due to the “sink” capacity of carpets to hold particulates as they settle from the air, and depends on a program of regular carpet maintenance. Other studies show that biological and chemical contaminants in settled dust were lower on carpeted floors than bare floors. A recent pooled analysis found that when bedroom floors were at least 50% carpeted, cockroach allergen concentrations were lower than when floors were less than 50% carpeted.

This study also concluded that solid floors are easier to clean and contain less dust than carpeted flooring.

George's analysis: The failure of this study is:

The lack of definition of what proper cleaning is and the methods and protocols needed.

The lack of acknowledgement and failure to understand that <1.0 um PM includes all viruses which fall in the range of 20 - 400 nanometers, and bacteria which generally range in size from 400 nanometers to 2.5um. and many other biological microscopic matter is disturbed and resuspended by minute airflow patterns due to typical human and mechanical activities. Larger PM > 10um are resuspendable with larger disturbances.

National Center For Healthy Housing Fact Sheet

Authors: Dr. David E. Jacobs, Rebecca Morley, Thomas Neltner, National Center for Healthy Housing; Dr. Joe Ponessa, Rutgers Cooperative Extension Carpets and Healthy Homes

Choosing the appropriate flooring surface for a school environment is a complex issue. To assist school personnel in determining which flooring is best for their school, we studied the bio-contaminant levels associated with carpeted and hard surface flooring. Two schools were selected, one predominantly tiled and one predominantly carpeted, as similar as possible with the exception of their floor coverings. Neither school was a ‘‘problem’’ building. Multiple bio-contaminants were measured. For flooring, there were statistically significant differences for all the tested bio-contaminants except fungi. The carpeted surfaces, being strong sinks, generally had higher surface loadings of the bio-contaminants, while the airborne levels were significantly higher over tiled floors. Significant differences in airborne levels were found for dust mass, spores, fungi, b-1,3 glucans, and endotoxins. The results suggest that carpet flooring was not the major contributor to airborne levels of bio-contaminants in these two non problem schools. Journal of Exposure Analysis and Environmental Epidemiology (2004) 14, S41–S48. doi:10.1038/sj.jea.7500357 Keywords: bio-contaminants, bio-aerosols, schools, flooring, carpet.

Comparison of bio-contaminant levels associated with hard vs. carpet floors in non-problem schools: Results of a yearlong study KARIN FOARDEa AND MICHAEL BERRYb a Microbiology Department, RTI International, Research Triangle Park, NC 27709, USA b Environmental Studies Program, University of North Carolina, Chapel Hill, NC 27599, USA

A comparison of the floor concentrations showed that the carpeted flooring had many times the loading of bio-contaminants than an equal area of tiled flooring. This was not a surprising result, since one of the advantages of carpet is that it acts as a sink and prevents dirt from being tracked around a space. Unfortunately, unless the carpet is well maintained, the loadings of bio-contaminants may build up until the carpet is no longer a sink but becomes a source of contamination. Regular maintenance is critical. It is clear from the data that the airborne bio-contaminants were found at higher concentrations over tiled floors than over carpet, as much as three times higher. There may be reasonable explanations for these differences that involve the HVAC systems and outdoor concentrations; however, it is unlikely that the flooring plays much of a role in the differences based on the aerosol properties of the particles involved. Small aerosol particles, such as those contributing to PM2.5, fungalspores, and biologicalcomponents such as endotoxins and b-1,3 glucans, tend to remain airborne for long periods. These particles do slowly settle to surfaces (hours) through movement in air currents and diffusion in quiet air layers. Once attached to surfaces, these small particles are difficult to dislodge into the air again. Detachment of particles from a surface is difficult to quantitate and poorly understood (Vincent, 1995). In general, adhesive forces are proportional to the particle diameter (d); while removal forces are proportional to particle mass (d3 ) for vibration, and detachment by air currents is proportional to the exposed surface area of the particle (d2 ) (Hinds, 1982). Furthermore, about 10 times as much force is required to remove 98% of the particles as that required to remove 50% (Hinds, 1982). As the size of particles decreases, it becomes increasingly difficult to detach them from surfaces. Therefore, large particles are easier to remove from a surface than small ones. One class of aerosol particles that was not examined in this study was the coarse particles, those with sizes larger than PM2.5 but smaller than PM10, or between 2.5 and 10 mm by aerodynamic diameter. These size particles settle rather quickly to the floor (minutes). From there, such particles may be stirred up again by people walking across the floor, by machines vibrating the floor, or by strong air currents. The coarse particles can serve as carriers for the biocontaminants that settled on them or mixed with them on the floor surfaces. In such cases, the higher airborne concentrations in the tiled-floor schools may provide a steady source of fresh biocontaminants onto coarse particles that are rather easily reintrained or detached from the floor. On the other hand, the much larger loadings of biocontaminants in carpeted floor materials may represent a larger reservoir of older, coarse particles that can be stirred up, although perhaps not as effectively as on the tiled floors. Table 6. Summary of statisticalanalysis of airborne data. SAMPLE LOCATION Indoor

Cited:

Air Concentration Outdoor Air Concentration CONTAMINANTS Source of Variation Source of Variation Schools Times Times* school Outdoor Air Schools Times Times* school PM2.5 Dust mass Mite antigen Cat antigen Cockroach antigen Fungi Total spores -1,3 Glucan Endotoxin Black box indicates statistically significant difference (Po0.05). Comparison of biocontaminant levels in hard vs. carpet floors ~ Foarde and Berry Journal of Exposure Analysis and Environmental

My analysis:

There are too many unresolved issues within these studies. Primarily, these studies continue to use Arizona Test Dust when actual dust which is found in homes is available inside of most home's vacuum cleaner filter bags. Using standardized dust because it provides similarly sized compositions of matter does not equate to the type and potential of actual dust, and, therefore, the most basic information necessary to form a conclusion about the inherent health potential and condition of the flooring surface. To be fair, several studies did make reference that ATD does not contain the biological soils found within common house dust, and that it is an important distinction for consideration

Additionally, they also fail to consider the importance that the particulate's ionic charge plays in the release and attraction of soils. ATD cannot simulate the enormous variables contained within actual house dust, it can only emulate the size of the particulate matter found within the home's environment. Ionic charge is significant and must not be overlooked. I.e. To explain it as simply as possible, particulate matter is either positively charged (cationic) or negatively charged (anionic). The greater the charge, the greater it's ability to hold onto a surface, such as dirt holding onto carpeting. If soil did not have a charge, practically, all soil could easily be removed with a vacuum cleaner, but as most of us have learned, that is not the case. Therefore, the ionic charge of the particulate matter plays a huge role in determining whether the particulate matter is re-suspended into the indoor environment or trapped and held by the flooring material.

That's where we find the benefits of carpeting as it simulates the role of a passive filtration system. The carpeting traps and holds the charged and uncharged particulate matter, whereas smooth surfaced flooring such as wood or tile does not contain fibrous material to trap and hold, thus allowing the particulates to be re-suspended into the air with much less effort as compared to the fibrous material construction found in carpeting.

Finally, the papers refer to maintenance and cleaning as a consistent variable without variations. As a professional in the carpet cleaning industry for the past 40+ years, I can assure you there is nothing more variable than the skill set and application of the carpet cleaning technician. I would venture to conclude that less than 1% of carpet cleaning technicians understand and apply the proper corrective cleaning measures necessary to provide an improved and healthier indoor living environment. The studies do suggest aggressive vacuuming, however, then they report that the airborne contaminates increase when exposed to disturbances such as vacuuming. The conclusion then should be that vacuuming contributes to re-suspension of contaminates back into the air. Or, should we conclude that vacuuming using the conventional method may be the problem? There are several other methods to dry extract soils from carpeting without excessively disturbing the trapped contaminates, which would mean less re-suspension of PM into the indoor air, however, those were not mentioned in any of the studies. Additionally, the fine PM which has landed upon the smooth surfaced flooring is more easily re-suspended back into the air. The greater the volume of suspended PM, the greater the exposure to potentially unhealthy issues and as a result the larger load ingested by the inhabitants. Properly performed carpet cleaning will reduce the disturbance levels and the suspended PM. I.e. a negative pressure extraction system, or non-vibrating vacuum cleaner interface will substantially reduce disturbance and lead to less PM re-suspension. When carpeting is cleaned correctly, the extraction step is emphasized as the most important step, however, as the studies have indicated, conventional vacuuming procedures are counterproductive. Most carpet cleaning technicians apply substantial volumes of water, but fail to remove enough to reduce drying times. They also apply detergent chemistry which contains optical brightening agents added to the rinse water. This leaves a residue that contains detergents and optical brighteners. The detergents dry eventually and attach to the carpet's fibers which in turn attract and hold greater volumes of PM.

The optical brightening agents are used to make the carpeting appear optically more appealing than it actually is.

[Optical brighteners (OBAs) work by absorbing invisible ultraviolet (UV) light and re-emitting it as visible blue light, creating a "whitening" effect that makes fabrics and paper appear brighter and whiter by canceling out yellowish tones. They are fluorescent chemicals that bind to materials and trick the eye into perceiving more light is reflected, enhancing vibrancy and masking dullness. ] ~ As provided by AI .

This topic is a whole discussion in itself for another report to come soon.

Citations:

See http://www.nationalacademies.org/hmd/Activities/PublicHealth/Health-Risks-IndoorExposure-ParticulateMatter/2016-FEB-10.aspx (accessed July 28, 2016).

-Resuspension of Particulate Matter from Carpet Due to Human Activity Jacky A. Rosati , Jonathan Thornburg & Charles Rodes To cite this article: Jacky A. Rosati , Jonathan Thornburg & Charles Rodes (2008) Resuspension of Particulate Matter from Carpet Due to Human Activity, Aerosol Science and Technology, 42:6, 472-482, DOI: 10.1080/02786820802187069 https://doi.org/10.1080/02786820802187069 Published online: 17 Jun 2008.