Is Your House Killing You

Is Your House Killing You?
By Dr. Richard Corsi
Produced by and for the Hot Science - Cool Talks Outreach Lecture Series of the
Environmental Science Institute. We request that the use of any of these materials include an
acknowledgement of Dr. Richard Corsi and the Hot Science - Cool Talks Outreach Lecture
Series of the Environmental Science Institute of the University of Texas at Austin. We hope
you find these materials educational and enjoyable.
1

At a certain point, early humans figured out it was best to build fires in caves below
an opening to the outdoor atmosphere (man’s first vent hood!).
3

Early human conditions still exist for roughly ½ of the world’s population, which uses
unvented indoor cook stoves. This is one of the top causes of death in the world
(4% of global mortality). There are particularly significant effects in women and
young children. My talk today will focus on our society, which is the developed
world. But we should not forget the other half of the world’s population, and I would
be remiss not to mention them today.
4

I mark the beginning of modern indoor problems as starting at the end of World War
II. Ask audience how our society changed immediately after end of WWII. Millions of
GIs came home and wanted to “get on with life,” and owning their own home was an
important part of this. Up sprang suburbs.
More homes on smaller lots = first attached garages (horrible invention from an IAQ
standpoint). Cheaper homes = new materials = material off-gassing, etc.
5

Point out that in 1950s and 60s there was a huge demand for products that made
life easier and more “luxurious.”
Plot = global production of synthetic organic chemicals (SOCs). A large fraction
were produced in US (this made the Houston ship channel!).
Take note of the huge jump after WWII. Most of the chemicals are used in products
we bring into buildings (or store in our new attached garages!). It is difficult to find a
house today that does not have a closet or shelf that looks like the photo in the
slide. This was a big change in housing … suddenly they were full of SOCs.
6

Image Source: Wikimedia
Another big change revolves around air conditioning. Before WWII, AC was mostly
found in movie theaters. In the 1960s and 1970s, we saw a big change in new
homes being built with centralized AC. It was advantageous to keep the outdoors
out (first first time!) because it saved energy and money. Sealing up homes
(weatherizing, etc.) had the effect of ratcheting down outdoor-indoor air exchange.
In the early 1970s, typical air exchange rates = > 1 to 2 per hour (explain). Today,
energy-efficient homes get down to 0.1/hr! So now we are building homes that off-
fgas and bring in huge amounts of new synthetic chemicals. We are also tightening
them up. What is the end result in terms of pollution? Audiences get this.
7

Pause to make point based on basic building blocks. Go through major factors in
picture and read to right. Go through simplest possible model (don’t worry where it
comes from) – simple but power for illustration. Go through terms in simple model
(lower left). Point out that over time E has gone up for many pollutants and as we
tighten buildings Qvent has gone way down. Net result = second term on RHS has
become much more important!
Control – this is an important point for those who want to purchase an air purifier …
i li htl l ti (d i t dj t d t i l d l igive slightly more complex equation (denominator adjusted to include a clean air
delivery rate term). Note that if CADR = Qvent the pollutant levels cut in half.
CADR = fraction of what goes through device that is removed (efficiency) multiplied
by air flow rate through device. Many manufacturers claim to be highly efficient, but
their devices have such low air flow rates that they are completely ineffective!
8

Pictured here are several types of Ion Generators in a testing lab at UT.
9

This is an extension of the last slide – where I speak about control systems (The
types that are heavily advertised on television as air purifiers).
Vertical axis = CADR (remind via equation)
Horizontal axis = particle size - talk about importance of particle sizes and show
here.
Ion generators with high efficiency but low CADR (effectiveness) – low flow!
Ion generators are relatively useless compared to HEPA filters And even emit airIon generators are relatively useless compared to HEPA filters …. And even emit air
pollution … which we will discuss later.
Also gives audience a feeling for CADR they should look for on packaging in stores
(besides telling them not to waste money on ion generators).
10

Slide intended to point out that it is not all about what is in the air, but also what
deposits on the floor.
Study showing ¼ of mid-western homes with DDT in carpet 20 years after it was
banned.
Extremely highly levels of PAHs in carpet of > 50% of homes
So bad that carpet is more contaminated than many federally-classified hazardous
waste sitewaste site.
Read Ott and Roberts quote from Scientific American
Why important … who rolls around on carpet, breaths adjacent to floor,
contaminates hands and sticks them in their mouth?
11

Quick question to audience.
12

Klepeis, N.E., et al., "The National Human Activity Pattern Survey (NHAPS): A
Resource for Assessimg Exposure to Environmental Pollutants," J. of Exposure
Analysis and Environmental Epidemiology, 11, 231-252 (2001).
Go through statistics: We spend 18 hours indoors for every hour we spend outdoors
We spend more time indoors than Scandinavians do!
We are the only people of the world who spend more time in motor vehicles than we
spend outdoors!spend outdoors!
Americans have evolved to being “indoor creatures”
So, we spend essentially all of our time in the environment that is by far the most
polluted environment we could spend time in. And we do nothing about this as a
nation!
13

Quick question to audience.
14

USEPA ranks environmental risks to public, and indoor air is NUMBER 1!
However, this is politically untenable, since the USEPA has no mandate to do
anything about the problem.
So, radon (a major indoor air pollutant that kills over 20,000 Americans/year) is
removed and given its own category.
This makes indoor air number pollution still much more significant than all of the
things we hear about in the media (outdoor air pollution chemicals in drinking waterthings we hear about in the media (outdoor air pollution, chemicals in drinking water,
hazardous waste sites, etc.)
Despite importance … we do nothing as a nation (others do a lot).
15

Dust Mite Image Source: Food and Drug Administration. All other photo credits
b dd d i h tembedded in photos.
Sources refer to emission – E in previous equation
Rest = quick collage … about three seconds per emission source.
I say one major point about each source as it goes by (importance or major pollutants
it emits).
The point here is to let audience know that there is a very diverse and large number of
sources indoors. The situation is complex. We know a lot about some sources
(cigarettes), and hardly anything about others (for example, incense).
I end on dust mites and leave the mite on the slide, as most people find this amusing.
My standard line is that most people in audience will go home and sleep with these
tonight.
Dust mites live on what food? Our skin flecks. We shed our skins about 13 times per
year not all at onceyear – not all at once.
They need to extract water vapor from air … they like where our mouths are … warm
and moist air into pillow or mattress.
Percentage of US population highly allergic to dust mite parts and fecal matter (large
fraction of body weight!)
Head on pillow, puff of these things, inhale …
17

Like to share some examples of sources we have studied at UT
18

Go through results for unscented and scented paraffin wax candles: More VOCs
from scented candles
Much more particulate matter from scented candles (explain why … slow burning
scenting agents in flame zone … millisecond to burn and can not completely ..
Condense and form ultrafine particles that are so small they can deposit in deepest
recesses of lungs … or even penetrate directly to blood).
Make point on human exposure. Candle mass emissions small relative to industrial
sources … but proximity is close and confined indoors. So exposure to particles
emitted from candles is very high.
One candle burning in a house is (in terms of exposure to someone in that house) is
equivalent to every coal-fired power plant and all other major industrial point
sources in Texas combined! (Calculation done in my graduate IAQ class).
Another way of stating this is that if you burn scented candles regularly and you
decide to stop after hearing this talk, you will have reduced your exposure to fine
particulate matter by an amount equivalent to shutting down every coal-fired power
plant and other major industrial point source in the State of Texas!
19

A chemical my students have studied a lot is p-dichlorobenzene.
Show results for emissions from different products (main point is that we have these
emissions and can now use them in calculations).
Note – I usually bring a number of these and other products with me in a sealed
container and pull them out to show the audience as I go through the talk.
20

Put results into a model using the “median US home”. Single products + super use
who uses three products (not unrealistic)
Describe plot and axes; point out median air exchange rate on plot (purple circles).
Discuss concentrations (these are very high!)
Point out what happens as house is tightened up (extremely high).
The risks associated with these concentrations is huge! (lead in to next slide)
21

One of my Ph.D. students is involved with analysis of personal concentration data for white and
Mexican American participantsMexican-American participants.
Discuss what a personal concentration measurement is (wearing a sampling badge throughout day
and analysis for toxic chemicals afterward). I will bring a badge and clip it to me for the audience to
see what one looks like.
We use these data to predict (using federally approved models) lifetime risks of contracting cancer in
number of people per million people.
Describe axes on plot (risk versus toxic pollutant), and point out what bars mean (median, bottom
25%, top 25%, etc.).
Discuss first cumulative cancer risk for each category (white and Mexican-American). Then focus on
p-DCB ---- much higher in Mexican American community, which uses these products more than
White Americans. The median in MA is 10 x that amongst white Americans. The highest quartile is
huge – over 2,000 in a million.
This value dwarfs any other environmental risks that I can think of …. Orders of magnitude more than
we worry about if living near a hazardous waste site and orders of magnitude greater than what we
worry about regarding chemicals in our tap water, etc.
22
IGERT: Indoor Environmental Science &
Engineering

This is a story of my involvement in a study related to toxic and irritating chemical emissions from
personal computerspersonal computers.
Several years ago I was contacted by a large computer manufacturer in Texas. They claimed every
time one of their large corporate clients received new computers the employees claimed they did not
feel good after switching on computers. I was asked to determine what was going on.
Studied several of the new computers and found emissions of volatile organic compounds (as shown
in plot – explain). Over 48 regulated toxic pollutants identified (more chemicals we could not identify).
All in relatively small amounts, but a lot nonetheless.
Rapid decay during first four days of operation (continuous) to leveling off (continued emissions from
h i h i l th t t k l t diff t f t ) I t ti i t thi d theavier chemicals that take longer to diffuse out of system). Interesting point … this company used to
do 4-day electronic burn in tests on all computers in a warehouse. Had to stop practice when got too
big. That’s when problem started. Solution … have company switch on all new computers on Friday
evening, ventilate building well, and let off-gas until following week (simple solution… but quite
effective!).
23

This is added just to show that problem is not limited to Texas companies!
Note suggestion at bottom- same as our suggestion.
24

One way to control indoor pollution is to clean surfaces. A common approach is to
vacuum flooring.
But the action of vacuuming (while generally valuable) can cause short-term re-
suspension of large amounts of particle mass.
Describe study done in 12 apartments in AustinDescribe study done in 12 apartments in Austin.
Show typical result (describe axes, vacuum on, vacuum off, and note elevated PM
for some time)
Highlight points at bottom of slide – very important link to previous slide, andHighlight points at bottom of slide very important link to previous slide, and
another thing that can be done to avoid problems if anyone in home has dust
allergies, etc.
25

Describe large study that my team did for the USEPA several years ago. Examined
chemical emissions from tap water to indoor air in kitchen sinks, showers, bath tubs,
washing machines and dishwashers. Washing machines and dishwashers are
particularly interesting as Americans often add sodium hypochlorite (chlorinated)
bleaches and detergents. We found VERY large amounts of chloroform formed in
each as chlorine reacts with organic soiling on clothes or certain foodstuffs
(particularly meats and tomatoes) on plates.
Di h h ti l l i t t d t t l hi h t t f tDishwashers particularly important due to extremely high temperatures – fast
chemical reactions! That warm burst of air that exits when the door is open is not
just humid air … Dishwashers are also very effective strippers .. Almost all of the
chloroform that is formed exits to kitchen air.
26

Plot shows average transfer efficiencies (describe as fraction of chemical that
comes out of water in device) for a range of surrogate chemicals that we studied. In
terms of transfer efficiencies, chloroform acts similar to toluene.
Approximately 40% emitted from washing machines and 95% from dishwashers.
27

Here I discuss with the audience how much concern there has been about
chlorinated by-products in tap water and the publics desire to avoid these. The
major culprit amongst these chemicals is chloroform (a suspected human
carcinogen – amongst suspicion of other health effects). The point I make on this
slide is that experimental results completed at UT coupled with water usage
patterns show that inhalation of chloroform emitted from water is actually a slightly
more important exposure pathway than actually drinking the water.
If di t th f hl f i i d i fi d h t t fIf we dissect the sources of chloroform in indoor air we find showers to account for
almost 60 and laundry about 30%. These two sources combined add up to about
as much as we are exposed to by drinking tap water, yet we do not use bottled
water to shower or do our laundry!
These results are just for the chloroform that exists in the tap water when it gets to
h If d th l i f hl f th t f i h four homes. If we now re-do the analysis for chloroform that forms in our home from
using chlorine in dishwashers and washing machines, using national average
dishwasher, washing machine, and usage statistics we get a very different story …
(next slide).
28

Now, inhalation is the dominant (by far!) pathway for exposure to chloroform, and
the large amount that actually forms in dishwashers dominates our total exposure.
So, if one wants to reduce their exposure to chloroform, drinking bottled water will
only get the US population about a 20% reduction!
Note to audience --- we are fortunate … Austin tap water is not heavily chlorinated
and so levels of chloroform are negligible in the water. Therefore in Austin our only
real exposure pathway is inhalation if we use chlorinated dishwasher detergent and
l d bl hlaundry bleach.
29

(Micrographs from American Thoracic Society, from American Review of
Respiratory Diseases, Vol. 148, 1993, Robert Aris et al., pp. 1368-1369.)
Here I will tell the audience that most people associate ozone with outdoor smog.
But in fact, our exposure to ozone is dominated by air we breath indoors (about
60% on average – more if we have major indoor sources). The ozone we breathe
indoors comes from: see list.
There is about four decades of great data on the negative health effects of exposure
to ozone.
Go through photo and describe what ozone does to epithelial cells – point out
neutrophils as source of inflammation, distorted cells, and cilia that bend over and
become non-functional. Why is the latter important … this is basically a paralysis of
part of our protective shield from air pollution. Cilia help to move mucous and
associated particles that deposit in lungs out. If they are paralyzed they can not do
thi Bi l i l t th t d it l i t i l d ti l i t tthis. Biological agents that deposit can colonize, toxic laden particles persist, etc.
So, ozone is BAD to have indoors, despite some companies who tell you it will
“clean” your indoor environment.
30

One source of indoor ozone are ion generators – remember these?
At UT we have tested most of the major IG available in market and heavily
marketed to Americans.
This is a photo of one of my colleagues (Jeffrey Siegel) in a chamber used to test
the various IG and other air purification systems.
Note that recent studies show that as much as 10% of the US population has
purchased IG for use in their homespurchased IG for use in their homes.
31

Source: Personal data from Corsi lab, unpublished. Here is an example of emission
rates (E) for several ion generators.
Point out axes and note term in equation that is represented.
You can see some differences, but generally a few milligrams/hr. These are
comparable to emissions from laser printers, but laser printers operate for a much
lower fraction of time . So ion generators are much more important sources.
But how important are these numbers what do they mean with respect to theBut how important are these numbers … what do they mean with respect to the
significance of outdoor ozone that we inhale? (prompt for next slide).
32

What we have done is to use our ozone emission rates from ion generators to
predict how much higher outdoor ozone levels would have to be equal the effects of
a single ion generator. We have used a “median” American home for our analysis.
We varied the air exchange rate from “leaky” houses (right side of horizontal axis) to
more energy efficient “tight” houses (left-hand-side of horizontal axis). Define
vertical axis as equivalent outdoor ozone increase caused by a single generator.
Note that for some generators in newer construction the effect is comparable to
moving from Fredericksburg to Houston.
Important (animation in on Bell’s work) about 10 ppb increase in outdoor ozone
leading to increased mortality (death) rates.
33

Some companies actually make explicit ozone generators that emit much higher
amounts of ozone than ion generators do. These companies often market
aggressively, showing babies in their advertisements, and often referring to ozone
as “activated oxygen” or “tri-atomic oxygen”. It is all ozone. It is bad for occupants!
Note the advertisement for a “Nursery Air Purifier”. Note read text.
The point about removal of particles as small as 100 microns is nonsense. 100
micron particles in the air pollution world are considered beach balls. They do not
t t th i d ll d t t d d l Thget past the nose region and generally do not stay suspended very long. They are
NOT IMPORTANT!
You can see what the US public is up against – there are those who take advantage
of a public uneducated on these issues.
34

Quick segue- transition to next topic. Make point that at UT we have become
leaders in studying chemistry that happens indoors.
Such chemistry has become much more important as we make homes tighter and
tighter to save energy. This gives chemical reactions much longer time to happen.
And boy do they happen!
The primary driver for indoor chemistry is ozone, and I have already described the
major sources.
35

Here I slowly explain how ozone attacks organic chemicals that contain carbon-
carbon double bonds.
The result is an ozonide (crab-like structure) that decomposes at the bonds shown.
The decomposition products are always carbonyls such as formaldehyde and “wild”
chemicals called Criegee bi-radicals that are extremely reactive and lead to the
formation of a wide range of by-products.
These by-products have been shown to be at best irritating and at worst highlyThese by products have been shown to be at best irritating, and at worst highly
toxic. They can also be corrosive in museums, telecommunication centers, etc.
36

So, what are the sources of these organic chemicals with C=C double bonds? They
are in dozens of things that are commonly found in our homes. Mention the huge
move toward “natural” or “green” products, including cleaners and fragrances.
These are composed of chemicals known as terpenes or terpenoids that are
generally very reactive with ozone.
So, tighter homes and more green products have lead to homes our homes
becoming intense chemical reactors!
37

Sarwar et al., Journal of the Air & Waste Management Association, 54: 367-377
(2004)
To illustrate I show here the results from an experiment done by one of my past
doctoral students.
He placed a single solid air freshener that emits terpenes in a stainless steel
chamber and emitted a modest amount of ozone.
The results were shocking Go through plot Define axes Show amount ofThe results were shocking. Go through plot. Define axes. Show amount of
particles in a cm3 of air (about the size of a single dice).
Show baseline before ozone injection. Show incredible increase on log scale. Note
growth wave as small particles are formed and then grow as new reaction product is
deposited on them.
38

If ozone chemistry is fast, and if Americans put on a lot of perfume, hairspray, and
colognes …. Could we be turning our heads into intense chemical reactors?
39

Go through statistics and point out the fact that if we can smell it (perfumes, etc.) it
is usually near our head at levels that are orders of magnitude greater than found in
background air in a house.
40

Evidence of ozone/skin reactions: Wisthaler et al., ES&T, 39: 4823-4832 (2005)
My team introduced the term “personal reactive cloud” to denote these reactions.
Go through sequence and discuss how reactions near head mean a lot of by-
products (like we talked about before) directly in the breathing region.
41

My students and I did some simple experiments. We built what we call a “near head
reactor”. I put on a few common colognes, hair sprays, perfumes, etc. and stuck
my head in the reactor. I was exposed to an amount of ozone that is LESS than
what we would find outdoors in Austin on a really bad day, and FAR LESS than one
would be exposed to outdoors in Houston.
We looked for by-products in my breathing zone.
42

Here is what we found. For four of the five products tested we saw a statistically
significant increase in ultrafine particles from before to after using product. And with
particles comes all of the other bad stuff! Imagine someone who gets all gussied up
in Houston and walks outdoors on a bad ozone action day. Their head region would
be figuratively on fire with chemical reactions.
43

So - there are often two types of responses by audiences who hear about all of this
b d t ff h i h O b l t l id (I d tbad stuff we have in our homes. One group becomes completely paranoid (I do not
want that!). The other groups says … It is all too much – who gives a darn – I can
not do anything to make things better (I do not want that). The right thing to do is to
recognize that this is an important problem. Become more educated, and take
control of your own home. YOU are the best person to help solve your indoor
environmental problems.
Continue list. Note .. There are SO MANY recommendations that I could give on
fhow to make things better that this would take another two hours of discussion. I
will encourage the audience to ask questions, and would also like to bring along a
one page handout to leave outside the room for people to take home with them.
44

To summarize …. Go through list.
45

In background when I answer questions. As needed I will ask people to see the
website for our Ph.D. program on Indoor Environmental Science and Engineering
for more information.
46

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