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CU Boulder study: routine household activities generate air quality on par with major polluted city

Cooking, cleaning and other routine household activities generate significant levels of volatile and particulate chemicals inside the average home, leading to indoor air quality levels on par with a polluted major city, according to a study by researchers at the University of Colorado Boulder.

Furthermore, airborne chemicals that originate inside a house don’t stay there: Volatile organic compounds (VOCs) from products such as shampoo, perfume and cleaning solutions eventually escape outside and contribute to ozone and fine particle formation, making up an even greater source of global atmospheric air pollution than cars and trucks do.

Researchers from CU Boulder’s Cooperative Institute for Research in Environmental Sciences (CIRES) and the university’s Department of Mechanical Engineering presented their recent findings during a panel discussion at the 2019 AAAS Annual Meeting in Washington, D.C.

Homes have never been considered an important source of outdoor air pollution and the moment is right to start exploring that. We wanted to know: How do basic activities like cooking and cleaning change the chemistry of a house?

—Marina Vance, an assistant professor of mechanical engineering at CU Boulder

In 2018, Vance co-led the collaborative HOMEChem field campaign, which used advanced sensors and cameras to monitor the indoor air quality of a 1,200-square-foot manufactured home on the University of Texas Austin campus.

Over the course of a month, Vance and her colleagues conducted a variety of daily household activities, including cooking a full Thanksgiving dinner in the middle of the Texas summer.

While the HOMEChem experiment’s results are still pending, Vance said that it’s apparent that homes need to be well ventilated while cooking and cleaning, because even basic tasks like boiling water over a stovetop flame can contribute to high levels of gaseous air pollutants and suspended particulates, with negative health impacts.

To her team’s surprise, the measured indoor concentrations were high enough that that their sensitive instruments needed to be recalibrated almost immediately.

Even the simple act of making toast raised particle levels far higher than expected. We had to go adjust many of the instruments.

—Marina Vance

Indoor and outdoor experts are collaborating to paint a more complete picture of air quality, said Joost de Gouw, a CIRES Visiting Professor. Last year, de Gouw and his colleagues published results in the journal Science showing that regulations on automobiles had pushed transportation-derived emissions down in recent decades while the relative importance of household chemical pollutants had only gone up. (Earlier post.)

Many traditional sources like fossil fuel-burning vehicles have become much cleaner than they used to be. Ozone and fine particulates are monitored by the EPA, but data for airborne toxins like formaldehyde and benzene and compounds like alcohols and ketones that originate from the home are very sparse.

—Joost de Gouw

While de Gouw says that it is too early on in the research to make recommendations on policy or consumer behavior, he said that it’s encouraging that the scientific community is now thinking about the “esosphere,” derived from the Greek word ‘eso,’ which translates to ‘inner.’

There was originally skepticism about whether or not these products actually contributed to air pollution in a meaningful way, but no longer. Moving forward, we need to re-focus research efforts on these sources and give them the same attention we have given to fossil fuels. The picture that we have in our heads about the atmosphere should now include a house.

—Joost de Gouw



Good piece of work there.
Lots of work for Procter and Gambol etc. to do.
It will be interesting to see how they approach it.
They can either try to bury it, or accept the findings and work out how to minimise the harm being done (by devising and selling new products).
Big market opportunity here.

Interesting also that it runs contrary to the very high draft proofing of the zero emissions house. They'll have to add more powerful ventilation and heat recovery units.
There is not much point in low CO2 if you are poisoning your family with cleaning products.


Cleaning products are one thing, but cooking vapors?  They may be fine particulates but a great many of those are probably harmless as they're made of something you're going to eat anyway.

Jason Burr

I have seen studies that compare grilling steaks and burgers to running a dirty diesel. And I have smelled plenty of strong cleaning chemicals over the years. I have to agree that there is a lot of VOC and vapors given off from both sources.

BTW - I think this is one of the reasons wood burning fireplaces are being regulated out of homes. At least in certain areas.


CPPs/NGPPs, ICEVs, wood/gas fire places, 1001 cleaning materials, nail polish, cheap paints, deodorants, shampoos, glyphosates, and some 4000 other industrial products/processes are progressively poisoning the food, water and air that we (and all living creatures) use.

The long term results may be disastrous unless we (or our children and grandchildren) better regulate responsible industries. EU countries (and California-Japan) may be moving in the right direction?

I have seen studies that compare grilling steaks and burgers to running a dirty diesel.

Perhaps in mass and number of particulates, but there's a huge difference in how they affect us.  Humans have been cooking meat over fire for more than half a million years.  We are adapted to the things that come off cooking meat; out of diesels, not so much.

I think this is one of the reasons wood burning fireplaces are being regulated out of homes. At least in certain areas.

The dose does make the poison.  We also have a certain amount of adaptation to wood smoke but adaptive mechanisms can be overwhelmed.


I think the point is to be aware of internal air pollution and take action.
Mostly, this is enforced by smoke detectors - ours go crazy if we cook steaks or chops on a very hot pan and we have to run around opening doors.

The cleaning fluid vapours are a more subtle thing as they do not set off smoke alarms.
So we will need better ventilation with heat exchangers to get rid of the air and hold onto the heat.
As @EP says, the dose makes the poison, so if we get the pollution out of the house and dilute it into eternal air, we are better off.
It would also be interesting to make a Pareto of the most harmful substances in typical homes. (Would be different from country to country).


This follows similar research showing that volatile aromatics or aerosols from perfume soaps paints cleaning products etc were (I recall) approaching 20% of such city air emissions and rising while those from autos were falling.
Intolerance to smoke from cooking and heating was thought a possible contribution to the demise of early hominoids. H. sapiens having a high tolerance to particulate compared to most other animal species.
When we hear of two pack cigarette equivalent cities being common, then that needs to be added to the background number and we know the consensus is that there is really no 'safe level ' above the W.H.O. internationally recognised limit.
I guess the take away message here is that we aren't likely to escape the outdoor pollution levels by staying indoor on an average day. Days of extreme will of course be a different story.

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