ADVERTISEMENT

The Dust That We Breathe Inside Our Homes

Published by Pat Rasmussen

Exposure and Biomonitoring Division, Environmental Health Science and Research Bureau, HECSB, Health Canada, Ottawa, and the Department of Earth and Environmental Sciences, University of Ottawa

These findings are described in the article entitled Contribution of metals in resuspended dust to indoor and personal inhalation exposures: Relationships between PM10 and settled dust, recently published in the journal Building and Environment (Building and Environment 143 (2018) 513-522). This work was conducted by Pat E. Rasmussen and H. David Gardner from Health Canada and the University of Ottawa, and Christine Levesque and Marc Chénier from Health Canada.

George Carlin: Dusting is a good example of the futility of trying to put things right. As soon as you dust, the fact of your next dusting has already been established.

ADVERTISEMENT

Have you ever created a dust cloud by plopping down on a couch, or gazed at dust particles floating in a shaft of sunlight from the window? Dust particles are constantly settling onto surfaces in our homes, only to become resuspended again every time we sit down or walk around, and whenever we vacuum carpets, sweep the floors, or make the bed. These are just a few of many everyday activities that cause the redistribution of dust particles into the air that we breathe. 

The chemical composition of dust particles in typical urban homes has been the focus of a nationally representative study conducted by Health Canada researchers, entitled “The Canadian House Dust Study.” The study’s first priority was to quantify lead contamination in dust, which can be a significant source of exposure for toddlers and pre-schoolers who accidentally ingest dust through normal hand-to-mouth activities. Later the Canadian House Dust Study examined a host of other inorganic and organic chemical compounds that accumulate in dust after being released from consumer products, furniture, building materials, coatings, combustion products, tracked-in soil and infiltrated ambient particles. Results for hundreds of compounds have been reported in a series of publications which collectively show that the ability of settled house dust to accumulate chemical compounds makes it an excellent indicator of residential contamination.

While accidental ingestion of lead and other chemicals in settled house dust can be a significant exposure pathway, researchers are starting to recognize the importance of inhalation exposures caused by breathing resuspended house dust. Most of what we know about indoor dust resuspension processes comes from studies of human exposures to allergens such as dust mites and pet dander.

Recently, Health Canada researchers questioned how the chemical composition of indoor air particulate matter (PM) is related to the composition of settled house dust. They first conducted lab experiments using archived Canadian House Dust Study samples, which showed that resuspended dust particles in the <10 ”m size range (known as PM10 or the “inhalable fraction”) tend to have higher trace element concentrations than the bulk dust samples (<80 ”m size range) from which the PM10 was derived. Then they compared the elemental composition of samples of dust collected from living room floors in Windsor, Ontario with samples of airborne particles collected in the same rooms.

ADVERTISEMENT

The results from the Windsor study confirmed that many trace elements are found in higher concentrations in airborne PM10 than in settled floor dust from the same room. Most importantly, the study showed significant correlations between elemental concentrations in the matched PM10 and settled house dust samples. Those correlations between elements in PM10 and settled dust provided new evidence that we do indeed inhale resuspended house dust in our homes. The researchers concluded that house dust makes a very useful sampling medium for investigating inhalation exposures in indoor residential environments – not just exposures to metal compounds but also to the myriad of synthetic organic chemicals such as plasticizers, flame retardants, and pesticides that are found in house dust. 

Additionally, the study showed that concentrations of many elements are elevated in the inhalable fraction (<10 ”m) of settled dust from heavily carpeted homes compared to homes with little or no carpeting. This observation is particularly relevant for understanding inhalation exposures because higher rates of resuspension are associated with carpets than with bare floors.

Another factor is the location of the home: previously the Canadian House Dust Study had demonstrated that indoor dust deposition rates are significantly higher in homes located near urban industrial zones than in homes in residential neighbourhoods located more than 2 km away from industry. In other words, that annoying film of dust on our bookshelves and coffee tables collects a lot faster depending on where we live. This observation about the influence of home location is also relevant to understanding inhalation exposures, because dust resuspension rates are higher in homes with greater amounts of settled dust. 

Comments

READ THIS NEXT

The 5th Dimension

The 5th dimension remains in debate, but many believe it could represent an undefined or unknown dimension in space that […]

More Than A Shade Of Difference: Photovoltaic Diffusion In Germany And Spain

While both Germany and Spain were among the first countries to promote the diffusion of solar photovoltaics (PV), both countries […]

First Image Of A Newborn Planet Captured

In the many years that astronomers have been watching the skies, they’ve hoped to get a glimpse of the moment […]

Militarization Of Police Doesn’t Reduce Crime, It Increases Public Distrust Of Police

The increasing militarization of police departments and police officers across the United States has been an intensely debated topic over […]

Eavesdropping Bats Make Frogs Pay A Price For Recycling Air When Calling

Many species of animals have elaborate sexual performances to attract mates. These complicated mating displays are often observable in multiple […]

Enhanced Expectancies In Golf Putting

Enhanced expectancies, or one’s expectations of being successful in a certain task, can lead to better performance and the acquisition […]

Towards A Feasible Deployment Of Solar Energy Technologies

The use of fossil fuels is being questioned for future energy requirements because of its environmentally hazardous substance emissions, price […]

Science Trends is a popular source of science news and education around the world. We cover everything from solar power cell technology to climate change to cancer research. We help hundreds of thousands of people every month learn about the world we live in and the latest scientific breakthroughs. Want to know more?