Impact of carpet on asthma and allergies: new studies indicate carpet can outperform hard surfaces to reduce dust and airborne allergens
By Darius Helm
After years of efforts to dispel negative perceptions, the carpet industry finally scored a victory after the National Institutes of Health’s National Heart, Lung and Blood Institute (NHLBI) recently announced that it was rescinding previous recommendations according to which the mat should be replaced with a hard surface. flooring to protect those with asthma and allergies. In fact, according to the Carpet and Rug Institute (CRI), a series of studies over the past few years show that carpets, when properly maintained, are actually better than hard floors at keeping dust and allergens out. in the air.
The question of whether carpet has a positive or negative impact on people with asthma and allergies has been one of the most important debates in the flooring industry over the past half century. It started in Sweden in the early 1970s with the determination by various associations and advocacy groups that carpet was harmful to the health of people with asthma and allergies, although there have been no studies. medical to confirm it. Nonetheless, this has led to a wave of carpet deselection in Sweden and neighboring countries and to some extent around the world.
At first glance, the performance of the carpet as a particle collector seemed logical. First, the carpet per square foot has an infinitely larger area that particles can land on compared to hard surface flooring. Second, particles can settle on the carpet, protected from any air movement, while the slightest breeze will sweep them across a hard floor covering. On this subject, there is no debate. Carpets are, in fact, a sink for dust and allergens, and hard flooring is not. Case closed, right?
Apparently, the logic was so unassailable that no one felt the need to validate through the scientific process. In 2007, the disbeliefs culminated here in the United States in an NHLBI report that said symptoms “happen or get worse” in the presence of carpets. The report also called the carpet a “precipitating and / or aggravating factor” and recommended replacing the carpet with vinyl flooring. And remember, that was in 2007, before vinyl producers moved en masse to replace phthalates – a class of chemicals involved in endocrine disruption – in their products with less dangerous chemicals, suggesting that the NHLBI may have drawn conclusions with insufficient understanding of the issues involved.
The new report, “2020 Focused Updates to the Asthma Management Guidelines,” released on December 3, 2020, states that when it comes to the certainty of the evidence on allergen mitigation interventions, in terms of carpet removal, “[i]the intervention makes no difference ”, reflecting the low certainty of the evidence.
This change in NHLBI guidelines is in part the result of a concerted effort by the IRC over the past eight years to revise its recommendations, including bringing industry experts to testify before the National Institutes of Health and by presenting studies that show how the carpet can play a positive role. in terms of indoor air quality.
According to Joe Yarbrough, president of CRI, in a well-maintained room, carpet will minimize particles in the air, improve indoor air quality and reduce impacts on people with asthma and allergies. Yarbrough says, “When properly maintained, [carpet] serves as a filter to retain [the particulates], so when properly aspirated or cleaned as recommended, these items are removed in a way that does not impact the person with asthma.
Perhaps the best way to understand how an allergen sink is positive and not negative is to consider filtration systems. Take a look at your car’s air filter, vacuum cleaner, or heating system. They all rely on the passage of air through membranes and materials – usually fiber-based or open-cell foam constructions – that have as much surface area as possible in order to capture small particles so that the air passing is effectively cleaned. Over time, they fill up with dust and allergens, so in order to function properly, they need to be cleaned or replaced on a regular basis.
In the case of hard surface flooring, dust settles on the surface but is not trapped like in carpet fibers, so drafts easily lift dust from the floor and circulate it through. the breathing zone before it settles on the floor again.
So, the case presented by CRI is basically that in two rooms identical in all respects except one is installed with carpet and the other with hard floor, more dust and allergens will circulate in the air. of the room with a hard floor. And over time, without additional particles being added to the space, the carpet will gradually pick up dust and allergens and reduce their presence in the breathing zone of the room, while the room with a hard floor will not will see no reduction at all.
However, all of this hinges on one essential condition, good maintenance. In order for the carpet to behave like an air filter, it needs to be kept clean, which means vacuuming regularly – a HEPA filter system is the best way to capture all of those particles – and occasional deep cleaning, like hot water extraction, to ensure that whatever is trapped deep in the fibers is released.
According to Yarbrough, to get the word out, CRI is working through a range of media formats “to ensure that the message of this recommendation change is clearly communicated among healthcare communities, especially those specializing in health care. respiratory diseases, asthma and allergies. areas of treatment.
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