Toxins in the Home: Indoor Air Can Be Polluted Too The Environmental Protection Agency says that the air inside your house could be more polluted — especially with lead, radon, and tobacco smoke — than the air outdoors. Guests talk about toxic dangers in common household products and in the very materials that make up your house.
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Toxins in the Home: Indoor Air Can Be Polluted Too

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Toxins in the Home: Indoor Air Can Be Polluted Too

Toxins in the Home: Indoor Air Can Be Polluted Too

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  • <iframe src="" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
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Up next: air quality.

Next week, CDC officials will begin testing air quality in trailers and mobile homes in Louisiana and Mississippi. The trailers are temporary homes for Gulf Coast residents displaced by Hurricane Katrina. Many of whom have experienced health problems that may be linked to exposure to formaldehyde, that's a chemical used in many construction materials in the trailers.

And if you're feeling safe and lucky about not having to live in a toxic mobile home, well, for the rest of the hour, we want you to think again, because one study done by the EPA concluded that for some pollutants, the air inside our homes may be worse than the fresh air outside. And research about toxins inside your home is baring that out.

Some homes, if they were regulated as a work environment, would not be fit according to government standards for you to be living there. You wouldn't be allowed to live in it. If it were a factory or facility that you are working in. But since we don't have any regulations for safe levels of toxins in the home, you can and you probably do still live there. So for the rest of the hour, we're going to look at household toxins, including some hidden in everyday products; when they react with materials in your home create a brew of bad air.

We'll talk about the connection between bad indoor air and health problems and find out steps that we can take to clean up the air inside our homes. So as winter comes and where everybody is spending more time locked up in our homes that we've sealed up because we want them to be as energy efficient as possible, you'd want to talk about this. Our number: 1-800-989-8255, 1-800-989-TALK. And as always, you could surf over to our Web site at

Let me introduce my guests, Richard Corsi, is the Bantel professor, of civil, architectural, and environmental engineering in the Cockrell School of Engineering in the University of Texas at Austin. He joins me from KUTI in campus. Welcome to the program Dr. Corsi.

Dr. RICHARD CORSI (Bantel Professor, Civil, Architectural and Environmental Engineering, Cockrell School of Engineering, University Of Texas): Thanks for the invitation, Ira.

FLATOW: You're welcome.

Paul Blanc M.D. is the author of "How Everyday Products Make People Sick: Toxins at Home and in the Workplace," published this year by the University of California press. He is professor of medicine and endowed chair of occupational and environmental medicine at the University of California, San Francisco. He joins us today from Stony Brook New York. Welcome to the program, Dr. Blanc.

Dr. PAUL BLANC (Author, "How Everyday Products Make People Sick: Toxins at Home and in the Workplace;" Professor of Medicine and Endowed Chair of Occupational and Environmental Medicine, University of California, San Francisco): Thank you for having me.

FLATOW: Richard Corsi, I quoted an EPA study that found that the air quality inside our homes is often worst, sometimes much worse. Can you tell us a bit about that study?

Dr. CORSI: Sure. That's actually an agglomeration of information that's been collected by a number of researchers over the last 20 years, and it's generally true for a very broad class of air pollutants and certainly true for those air pollutants we classify as toxic air pollutants or toxic air contaminants.

The number two to five is sort of a generalization. Sometimes, the amount of indoor air pollution is even more than five times what it is outdoors, if we're engaged and certain activities indoors, or if we purchase a new home that's off casting a lot of these chemicals. And that number is not true for a smaller mist of pollutants like ozone, which generally exists in much lower levels indoors because when it comes indoors from outdoors, it's reduced by a chemical reacting with surfaces indoors.

FLATOW: What are these leading toxins that we're talking about?

Dr. CORSI: Well, you know, things that are heavily regulated outdoors that we see it in higher levels indoors, things like benzene and toluene and styrene, formaldehyde, which you mentioned in your setup to this interview. It's just some examples, but there are literally hundreds of different chemicals that I could list here, and you probably don't want to go through the whole list.

FLATOW: Well, I…

Dr. CORSI: But those are some of the biggest.

FLATOW: Well I guess the big - the take-home message that we talked before about is that if this was a public place or a place regulated - a workplace, there would be rules against you working in such conditions, but there are none in your home. Is that correct?

Dr. CORSI: That's true in some situations and for certain pollutants, that's correct, yeah.

Dr. BLANC: And of course, that would seem that somebody would actually enforce the workplace rules.

FLATOW: Dr. Blanc?

Dr. BLANC: And, you know, the number of inspectors we have, it would take another hundred years for them to get to every person's workplace. So sometimes, these things are put into those terms, but it shouldn't be taken to belittle the true and real hazards that exists and still exists in the workplace. And in fact, many of the problems that we see in the home, we only know about them because the canaries in the cave where the people are exposed on the job.

FLATOW: Tell us what you see in the home that are particularly troubling to you.

Dr. BLANC: Well, you know, one of the most common household chemical toxic problems reported to poison centers around the country, for example, are misadventures with regular household bleach. Right now, we have lots of products on the market that people use to clean their tiles and other cleaners that are acid-based. And when those are mixed with regular old hypochlorite bleach, it releases a chlorine gas cloud in the house.

FLATOW: You mean, it's a - it's putting together chemicals from different sources that normally stay apart, but when you mix them together, something else happens.

Dr. BLANC: That's right. And people may not know they're mixing because you can use them sequentially. First, you use one thing; it doesn't get you the effect you want so you use something else.

FLATOW: So you put the chlorine bleach on top of which you add before and, poof, something else comes out of it.

Dr. BLANC: Right, and a lot of people think that the only problem is when you mix ammonia with chlorine, and that's a problem too. But this other problem is just as big - bigger.

Dr. CORSI: We've actually seen quite a bit of chloroform formed when you use sodium hypochlorite-, chlorine-containing dishwasher detergents and laundry detergents in washing machines and dishwashers. It's a major source of chloroform in residential buildings.

FLATOW: You mean, there's chloroform coming out of your dishwasher.

Dr. CORSI: Absolutely. And…

FLATOW: How does that happen?

Dr. CORSI: Basically, there is sodium hypochlorite chlorine in about half of all dishwasher detergents that are sold and it reacts with the food stuffs, particularly proteins and meat products as well as some of the chemicals that are in tomato paste and tomato sauce. And it - it's very effective at forming chloroform and we've seen enormous amounts of chloroform formed in dishwashers and released from dishwashers during the dishwashing and when the dishwasher door is open.

FLATOW: So you open that door and beside the steam coming out, you have a face full of chlorine.

Dr. BLANC: But, you know, there are also problems when people don't mix products, but simply generate a fine spray of an irritant. And that can occur with some of these bleached products that you sprits on surfaces, as well as, I think, mostly what we experience to when they've used these aerosol plastic cleaners for their roasting pans or whatever.

FLATOW: Well, if these are so dangerous, why are they not regulated? And don't we have labels and skulls and crossbones and people complaining about it?

Dr. BLANC: Well, you know, the main government agency which is responsible for many of these consumer products is something called the Consumer Product Safety Commission, which is really the poorest stepchild of all of the regulatory agencies. It's got a history of bringing ineffectiveness to a new level with each succeeding year it seems. They are the ones who brought us the Chinese-tainted toys saga.

FLATOW: Richard Corsi, do you agree?

Dr. CORSI: I agree. My experience recently has been related to products that release ozone in the indoor environment. I was fairly disappointed in the Consumer Product Safety Commission's report and decision on that product. I had actually written a 55-page report in response to that and sent it to them, and apparently fell on deaf ears, so.

FLATOW: Well, we'll get back to that. I want to talk about that because a lot of air purifiers out now that release ozone into the atmosphere and other - we'll talk about these and other devices.

We're going to take a short break and come back and talk lots more with Richard Corsi, University of Texas at Austin, and Paul Blanc, who was at the University of California, San Francisco.

Your questions about indoor air. We'll talk about what you can do about it and some of the more hazardous chemicals that are around us. So stay with us, we'll be right back after the short break.

(Soundbite of music)

You're listening to TALK OF THE NATION: SCIENCE FRIDAY. I'm Ira Flatow.

We're talking about toxic substances in your home with our guest today. Author Paul Blanc who is author of "How Everyday Products Make People Sick: Toxins at Home and in the Workplace." Richard Corsi, professor of civil architectural and environmental engineering at the University of Texas at Austin. Our number: 1-800-989-8255.

Let's go the phones because a lot of people, as you can imagine, are interested. Let's go to Mason(ph) in Phoenix.


MASON (Caller): Hi. Thank you for taking my call.

FLATOW: Mm-hmm.

MASON: I just have a quick question, a lot of air-conditioning companies sell, I guess, machines or attachments you can connect to your central AC system, some of them to swiftly help purify the air in your house using like, ultraviolet lights and things like that. And others have of which say they'll bring outdoor into your house so that the air in your house isn't stagnant. Are those worth getting - I guess that's my basic question, how effective are they?

Dr. BLANC: Good question.

Dr. CORSI: I'll attempt to answer that.

Dr. BLANC: Yeah.

Dr. CORSI: There are a lot of different products on the market that you can use in your HPAC systems. Some are very effective, some are not. Most people buy HPAC filters that are fairly worthless with respect to protecting public health. They are believed removing cat hair in that type of thing. The more outdoor air you can bring in in general, the higher the ventilation rate, the better the quality of indoor air is going to be in general.

And if you can control where the outdoor air comes in, and some higher-end homes are now doing that in the United States, it allows you to actually remove outdoor air pollution on its way into the house. And that's not the way most houses are designed. So for those types of systems, if you can control the outdoor air, where it comes in and treat it immediately for any outdoor air pollution in the air, that's generally a good thing to do.

FLATOW: What about these air purifiers that people are buying that use ions to purify the air. I noticed consumer reports in the last issue, they said they had recommended these in the past, but they're no longer recommending them because of the ozone that they put out.

Dr. CORSI: Right. There's actually two problems with ion generators and we've been doing a lot of research on that topic here at University of Texas. And one of my colleagues is, Dr. Jeffrey Siegel, he's really led those projects. One is that when you compare them with comparably priced other devices, portable air purifiers, they are largely ineffective. I mean, they don't remove a lot of particular matter from the air.

The second problem is that they do emit ozone, they don't emit as much ozone as an explicit ozone generator, but they do - most of these devices do emit enough ozone that it can raise levels of ozone in indoor air to levels that are of some concern, but also the ozone engages in chemistry indoors, which leads to a lot of other byproducts like formaldehyde and other what we call secondary products from these chemical reactions. So they are largely ineffective and also emit ozone, which is never a good thing.

FLATOW: Paul Blanc?

Dr. BLANC: Well there's also, I think, a larger societal issue, which is, do we want a system where each person is on their own where they have to somehow purify their indoor air and purify the water that comes with the faucet or would we rather have public health protective standards that make sure you're not bringing in products into the home, which can muddy the air that you breath. Or, that you have, for some reason, not the ability to open the window and get the air that's around you because of hazards. And I think that's the principal that shouldn't be forgotten.

FLATOW: How much should you rely on your nose for things that might be hazardous? I mean, you bring in new carpeting, there's glue, there's you know, plastics that come in. We know that these things are out-gassing some sorts of chemicals. Should we be wary of these things?

Dr. BLANC: Well, you know, one of the problems with odors as a warning is that with time - with certain chemicals, there's a mechanism by which you lose the ability to smell them at those levels. That's the one issue.

Another issue is that just a simple matter of fact that smells aren't always the best warning. There are things, which are quite toxic, which you're just not capable of smelling or don't have a strong odor.

There's another way in which though the nose could be a warning and that is in terms of a runny nose. Because a lot of times, allergies that are manifested by runny nose in response to various exposures are the harbinger of what will go on potentially to become an asthma-type response if exposure keeps going.

One good example of type of household product in which that can occur - all the modern two-part glues that people love to use - super glues and related things. Most of those types of chemicals have the capability of inducing sensitization on people who use them. The more you use them, the more the problem is so that's why in the workplace, it's more of a problem, but it can be a problem at home too.

FLATOW: Rich Corsi?

Dr. CORSI: Yeah, I agree with Professor Blanc on that issue. I would point out that there are certain products where if you can smell them, then it's telling you something important. And I'll give you one example. Moth crystals, moth cakes, moth balls are made out of paradichlorobenzene. They are pure paradichlorobenzene, and there's a lot of concern about the toxicity of that compound. And the odor threshold for that compound is quite high.

And so when you walk into a room and somebody's home where there's moth crystals and you smell that kind of moth crystal smell, moth ball smell, you're being exposed to really high levels of that particular chemical. And if you actually do a conventional risk assessment as the EPA does with many chemicals for that particular chemical, the risk associated with breathing the air when you can smell that chemical dwarf just about any other pollutant you can think of other than radon into our environment.

FLATOW: Let's go to Richard in Little Rock. Hi, Richard.

RICHARD: Yes, hello. My comment was in regards to the latest news about the FEMA trailers. And I wonder if what - if problems with that has been identified. And if so, how that would compare with other new homes that are being built that are not trailers? Because I had a brother-in-law that had a brand new $300,000 home. And when we would go visit overnight, I would get -develop nausea and get sick to my stomach in, you know, a real bad way just overnight, you know, in a $300,000. So…

FLATOW: Yeah. That's a good question. If, you know you're testing trailers, why don't we have a standard to test new homes when they're built, whether they're livable, safely that way?

RICHARD: Well, again, that may come down to jurisdictional squabbles; who's actually going to make the standard and enforce it. Most building codes, in fact, as opposed to some of the things we're talking about are completely local affairs. So…

FLATOW: We have people who test for radon now. Could we not expand that test for other toxic substances?

Mr. CORSI: We can. But the public has to become educated on knowing what things to ask, to be tested for and its contingencies in home sales and that type of thing. I think one of the issues is educating the public. And we haven't done a very good job at that in the United States.

I'd like to also respond to the caller, I guess. The levels in the FEMA trailers that I've seen far exceed sort of typical levels, even in new homes in the United States. The levels in the trailers are just off the scale. And one of the problems we have with new homes in the United States is if we've move towards, you know, energy-efficient green homes and we've really ratcheted down on the air exchange rates on those homes, the amount of outdoor air we bring in, it allows things like formaldehyde to accumulate.

So even if we reduce the amount of formaldehyde in pressed wood products, for example. As we tighten down on the air exchange rates in buildings, the level still accumulate to the levels that can actually be quite irritating to people, if not toxic.

FLATOW: So is ventilation - is that the single best way to combat whatever is in the air?

Mr. CORSI: I would say the best way to combat indoor air quality problems is to remove sources, if you can; to basically, don't engage in activities that involves sources that emit these kinds of chemicals we're talking about. I think ventilation is probably the - is the second thing to do upon.

FLATOW: Well, how do you know when you bring something in your house how bad it is?

Mr. CORSI: Again, I think that's an issue of public education. And this field that we're talking about right now is not nearly as mature a field as other environmental fields in our country. We know a lot less because there aren't the regulatory drivers that that Professor Blanc talked about, and there hasn't been nearly as much research, if there has been, say, in the drinking water field or outdoor air pollution field. And so the public is less educated because we simply know less. And what we do know, we haven't been very effective at getting out to the public.

RICHARD: And if I wanted to bring home certain substances into my home - you know, if I was an idiot, I couldn't do it because I wouldn't be allowed to buy it and it wouldn't be on the marketplace. So requiring people to have so much knowledge is not the safest way of going. You shouldn't have to have a degree in chemistry before you go down the aisles of your supermarket, buying a cleaner for your bathtub.

FLATOW: So what should we do then?

Dr. BLANC: Well, part of it should be restricted the sales of certain materials.

FLATOW: Give me, give me an example.

Dr. BLANC: Well, I'll give you one example. You know, we see these advertisements for glues that takes two trucks to pull apart the handle after you reglued it. I mean, there's — what's the vital purpose is that really serving? If I can, you know, be so boldest to ask.

FLATOW: Yeah. Those instant bonding glues.

Dr. BLANC: Yeah, of which there is a myriad. Some of them really, you know, are probably more reactive than others or clearly more reactive. That's just a small example. The clue is taking those steps with other things. We don't let people buy lead paint to paint their houses with anymore.

FLATOW: Rich, you studied talking about — you've talked about something called near-head chemistry, how you can get a burst of chemical reaction right around your heads because the products are reacting with stuff in the air. Talk a bit about that.

Dr. CORSI: You know, Americans are a bit of the aromatherapy freaks of the world, if you will. I hope that's okay to say. But we tend to love scented products. And a fraction of our population wears a lot of scented products on their head, on their skin - perfumes, colognes, hair sprays, that type of thing. And it turns out that most things that smell really good are also extremely chemically reactive. They're easily oxidized. And the most, you know, the thing that they oxidize most with is ozone. So you can imagine that if somebody puts perfume and colognes on, they have very, very high levels of these nice-smelling things around their head.

And when ozone comes in a close proximity of their head, lots of chemical reactions occur very fast. Lots of by-products are formed, including formaldehyde; ultrafine particles that can make their way into the bloodstream, and other by-products. So We've been doing some research on that topic here at U.T. And it's amazing what you can actually form in the breathing zone if somebody that's wearing these things, that they're exposed to relatively low levels of ozone, which should be much, much lower than what the U.S. EPA consider to be safe outdoors.

FLATOW: If you are outdoors, where levels are higher, that would be - you'd be standing in a cloud of this stuff.

Mr. CORSI: Basically, your head would be on fire with chemical reactions. That's right.

FLATOW: What an image.

(Soundbite of laughter)

FLATOW: 1-800-9898-255. Let's see if we can get a phone call or two in here. From Fatima(ph) in Sandy Springs, Maryland. Hi, welcome to "Science Friday."

FATIMA (Caller): Hi, how are you?


FATIMA: Just a quick question that's on my mind for a couple of days. I have a friend who just had a baby, and they're planning on moving into a brand new townhouse, just made. So my question is how long should they vent it out, if possible? And how long should they wait before moving into it, with all the off-gases from carpets and paints and what have you?

FLATOW: Good question. Rich, do you want to tackle that?

Dr. CORSI: It's a great question. There was a study done several years ago, and the author slipped my mind. Maybe Dr. Blanc remembers it. It was a German study that showed a fairly large number of newborns gong home to homes that had recently renovated nurseries versus homes that didn't have renovated nurseries.

And the babies that went home to recently renovated nurseries had suppressed immune systems and more respiratory infections than those that went home to the non-renovated nursery. And I think of the keys - and I tell this to my students all the time - is that, you know, newborns and the elderly - but if we're talking about newborns, are particularly susceptible to, sort of, exposure to chemicals that may not hurt anybody that's listening right now if they're adults.

But when the immune system of young children is developing, exposure to chemical clouds can have all sorts of effects on their immune system. And Dr. Blanc is actually, I think, is much better to respond to that than I am. But I think we have to be concerned about newborns and fetuses.

FLATOW: We're talking about toxic substances. It's our TALK OF THE NATION: SCIENCE FRIDAY from NPR News.

Dr. Blanc, you want to fill in?

Dr. BLANC: Well, I think it's - like everything else, it's relative. It depends on where the person is living now. I think it would take a lot of - a lot more data to emerge to show a clear pattern of problems. But, you know, clearly people do renovations around their home sometimes while they're still living in them or, you know, poorly, poorly advised.

And even though we've gotten rid of some products, we still have other ones that people can inadvertently use. But I don't think that there's a clear enough pattern of data yet to comment on time periods before moving into houses and so forth. And I could certainly imagine scenarios where it's better to move into that house now than to stay where you are. So…

FLATOW: In the few minutes I have left, what do we do and how do we clean our house out of some of these toxic products? What steps should we take? I'll ask you Dr. Blanc, first. What do we do?

Dr. BLANC: Well, I think the first thing is common sense. You know, you use products that are reasonable to the job. Don't — certainly there are certain things that are absolute. You should never bring home an industrial-strength product that's not marketed to the general public. You should be careful about combining products and using more materials than need to be used for the job in question.

It's always good to have as much ventilation as you can. The areas in which people use products where they tend to get in the most trouble, in fact, are in small and closed spaces. A bathroom is the best example of that. But you can imagine scenarios where people are doing - tinkering in their household basement…


Dr. BLANC: …that's poorly ventilates…

FLATOW: And the spraying paint and things like that.

Dr. BLANC: Absolutely. And there's - we haven't even started, really, to delve into the whole issue of crafts and hobbies and various things that people can do that can get them into trouble.

FLATOW: Richard, you want to add?

Mr. CORSI: Yeah. Let's say, first, as Dr. Blanc mentioned, avoid products that, we know cause problems. Candles and incense are something we didn't talk about. Avoid them. Avoid any combustion products in the home. Avoid products that emit ozone. If you are bringing products home and you're not sure about their contents, which is true a lot of the time, try not to store those chemicals in a place that you might be exposed to them.

FLATOW: Well, let me go back for a second because I have a minute. We're in the holiday season, I can't let you go buy with that without candle and incense talking about that.

Mr. CORSI: Sure. Scented candles actually emit very large amounts of ultrafine particles. And these are particles that are just the right size that penetrate deep into our respiratory system. And depending upon what the candle is made of - if they're paraffin-based candles that are doped with scenting agents, you can also form some fairly toxic compounds that actually are associated with the particles that are conveyed into the blood.

And my students have done some work in this area and looked at scented versus unscented candles to see major differences in the two. Scented candles seemed to be particularly bad in terms of emissions of organic compounds, some of which are toxic like benzene, as well as particulate matter.

FLATOW: Any other kind of scented flaming things we should be worried about?

Mr. CORSI: As I mentioned, incense.

FLATOW: Incense. Same problem?

Mr. CORSI: Same problems there, yeah.

FLATOW: All right. Well, hopefully we'll have a safer holiday season. And folks, well, take a little bit more time to think about what they're putting on their faces and stuffs that get to the ozone.

I want to thank you both for taking time to be with us. Richard Corsi, the Bantel professor of civil and architectural and environmental engineering in the Cockrell School of Engineering at the University of Texas at Austin.

Paul Blanc. Dr. Blanc is author of "How Everyday Products Make People Sick: Toxins at Home and in the Workplace." He's also a professor of medicine and endowed chair of Occupational and Environmental Medicine at the University of California in San Francisco. Have a great holiday weekend for both of you.

Dr. BLANC: Thank you very much.

Mr. CORSI: Thank you.

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