CHAPTER THREE

Why Are We Ignoring the 90 Percent?

In a modern society, total time outdoors is the most insignificant part of the day, often so small that it barely shows up in the total. The finding that emerges is that we are basically an indoor species.

—W. R. OTT

“WHY ARE WE IGNORING the 90 percent?” This is the question with which Joe likes to start most presentations, to get the audience thinking about the importance of the buildings we live and work in for our health and the bottom line. There are two parts to his equation: time and money.

Let’s start with time: studies have found that in North America and Europe we spend 90 percent of our time indoors.¹ It isn’t a perfect formula—some jobs have you out and about more, and kids tend to spend a little more time outside than adults—but for most of the developed world, it is more accurate than you might think. (In some places and in some seasons, that 90 percent is actually an underestimate. Joe once quoted the 90 percent figure while presenting in Abu Dhabi and heard chuckles in the audience—in the United Arab Emirates, it can be more like 99.9 percent indoors for some people.)

To put this 90 percent figure in perspective, it’s useful to think of what it means in terms of our own lives. By the time we hit 40, most of us have spent 36 years indoors. Try it for yourself: take your age and multiply it by 0.9. That’s your indoor age. If we are lucky enough to live to 80, most of us will have spent 72 years inside! We spend nearly all of our time indoors—so much so that Velux, a Danish company that specializes in skylights, cleverly branded us as “the Indoor Generation.”² When we look at it this way, in terms of years, it becomes obvious and intuitive that our indoor environment would have a disproportionate impact on our health.

So let’s break down that 90 percent and see where we spend our time. (Note that this section is based on research in the United States; the specific numbers will vary from country to country, but the basic facts don’t change in most parts of the world.) We tend to split our time among our homes, our offices, our cars, and an assortment of other indoor places like restaurants, stores, gyms, and airplanes. For kids, this looks very different. By the time they graduate from high school, they will have spent 15,600 hours inside a school. (Incidentally, as Harvard professor Jack Spengler likes to point out, schools are one of two types of buildings where we force people to spend time indoors. The other is prison.)

Sometimes we think that all we really need to do to advance the Healthy Buildings movement is mention this “90 percent” fact. After hearing that, how could anyone conclude that the indoor environment does not impact our health? Heck, we spend a third of our lifetimes in one little box on this planet—our bedrooms!

Here’s a weird but helpful way to think about all of this indoor time, courtesy of Rich Corsi, dean of engineering and computer science at Portland State University, an outstanding building scientist with a clever take to put this in perspective: “Americans spend more time inside buildings than some whale species spend underwater.”³

What?! It’s kind of hard to wrap your head around this—that whales spend more time on the surface than we, as land mammals, spend outdoors—but it’s true. We would never go about trying to understand whales by studying the air they breathe when they are at the surface; we study them where they live, underwater.

And yet that’s exactly what we do with humans. For all this time spent indoors, we tend to focus much more on outdoor air quality than on indoor air quality. Check any newspaper or news site on any given day and you are likely to see a story about the hazards of outdoor pollution, but how often do you see a story about building health?

Our regulatory system is also geared toward the outdoor environment, too. In the United States we have the Clean Air Act, which set National Ambient Air Quality Standards establishing limits for the six so-called criteria air pollutants: particles (PM_2.5 and PM₁₀), lead, ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide.⁴ Many other countries have similar standards for outdoor air pollution.⁵

But what about a “National Indoor Air Quality Standard”? No such thing. The only things akin to this in the United States are the legally enforceable limits set by the Occupational Health and Safety Administration (OSHA) for exposures to pollutants indoors. But before you start thinking that this means we’re all set, you should know that very few scientists, if any, would argue that the OSHA limits are truly protective of health. Even OSHA admits this. From its own website: “OSHA recognizes that many of its permissible exposure limits (PELs) are outdated and inadequate for ensuring protection of worker health.”⁶ That’s because OSHA was created in 1970, at which time “permissible” exposure limits were set for many chemicals based on a report from 1968, and those existing, unprotective limits were grandfathered into the new law. And as for new permissible exposure limits, OSHA has only created 16 since 1970. The last one was in 2006, for hexavalent chromium, a toxic heavy metal that is linked to respiratory cancer, asthma, skin irritation, and liver and kidney damage. This is not protecting us. And quite frankly, if you encounter any of these regulated hazards in an office building at the OSHA “permissible” limits, something is really amiss.

Why Are We Ignoring the 90 Percent? Part II—Money

The second 90 percent that we are ignoring is the true cost of operating our buildings: the people inside. Most companies spend as much as 90 percent of their budgets on human resources, a figure largely driven by their salaries and benefits—and as we’ll see in Chapter 4, their productivity.

The 3-30-300™ rule of real estate was created and popularized by the global facilities management company JLL.⁷ It’s intended to show a company’s relative per-square-foot costs across three factors—utilities, rent, and people. The rule goes like this: for every $3 a company spends on utilities like electricity and heat, it spends $30 on rent and $300 on payroll. This realization can make a focus on miserly utility spending, say, for ventilation, look pretty silly if the expensive assets—the humans—are not functioning at their best.

This rule of thumb can be corroborated through multiple sources. For example, the Building Owners and Managers Association International 2018 Office Experience Exchange Report indicates average office gross rents of $30.35 per square foot for private-sector office buildings, average utility costs of $2.14, and total space per employee of 288 square feet (inclusive of corridors and lobbies).⁸ As offices get smaller, a number like 250 square feet per person is becoming more typical. From a salary point of view, in Massachusetts, the gross wages for job titles like advertising sales agent, tax preparer, and computer user support specialist—the kind of people who would make up the bulk of typical office users—are about $65,000 per year, per US Bureau of Labor Statistics.⁹ After including other costs paid by the employer, the fully loaded cost per employee would be about $75,000 per year. This divided by 250 square feet works out to $300 per square foot per year as the compensation component. While the 3-30-300 rule of thumb is a generalization and a simplification, the order of magnitude is appropriate and useful. Some professions pay much more. When higher salaries are considered, the impact of productivity becomes greater and the impact of energy savings becomes even smaller.

Just as we pointed out earlier in the context of how much time modern people spend indoors, once again the building industry discussion has missed the key 90 percent—the impact of the big expense, the people. Financial types tend to focus on the 10 percent: the rent and utilities spend. Don’t get us wrong, these costs are critically important, but this has been the sole focus of the building sector for far too long. Think about it this way: the entire green building movement, with billions of square feet of office space registered globally, was largely built to chase a small subset of that 10 percent—the 1 percent costs of energy, waste, and water when looked at in terms of total cost of occupancy.

The reason for this focus on the 1 percent is largely that these are easy targets. They are easy in two ways. First, it’s simple to calculate a return on investment based on energy savings. If you invest in an energy recovery ventilator, for example, an owner can quickly see that the upfront capital costs for the equipment will be recouped in a few years. It’s a straightforward calculus—executives can literally do the math on the back of an envelope. (To be fair to those who do energy modeling, it’s not exactly “easy” in the absolute sense; considerable sophistication and expertise go into building these models, but it is certainly more easily quantifiable than health.)

Second, it’s easy to meter a building for energy, waste, and water. Take the building you’re sitting in or that you own or manage, and we bet with just a little effort you could find out precisely how much energy it uses in a typical year. That’s because it essentially only takes one or a handful of cheap sensors and a couple of utility bills to understand energy use in your building. That means that the return-on-investment calculus can be supported by hard data, which means it can be traded, financed, and guaranteed, as energy service companies do every day.

But now consider the people in your building, that crucial 90 percent of your costs. How do you “meter” the health of people in a building? Or even on one floor, or in one room? This is not a trivial undertaking. And because it’s hard, it has been a barrier to advancement. We measure energy really well, so we manage it. But we’ve ignored the people side of the equation, and, as predicted, we’ve failed to manage this opportunity. This is something the two of us have been thinking about for some time, and in Chapter 9 we will give you tools for metering the health of people in a building.

We’re certain you don’t need this, but we’ll do it anyway to drive the point home. That 90 percent represents a massive opportunity going forward. Said simply: The indoor environment matters for health and wealth.

Full stop. You can probably close this book right now.

The Indoor Environment’s Three-Pronged Assault on Our Health

Now that we have the basics covered, we want to broadly explore the indoor environment and how it impacts our health. (We’ll get into the important details of the financial impacts in Chapter 4.) In the remainder of this chapter, we will talk about what the science says, and then we’ll give you a framework for how to think about minimizing your exposure and risk.

Indoor Assault 1: The Dirty Secret of Outdoor Air Pollution

We want to share something that will likely shock you: the majority of your exposure to outdoor air pollution can occur indoors. It’s the dirty secret of outdoor air pollution.

Don’t believe us? Let’s do some basic math to prove it.

Let’s say we are in Los Angeles, where the outdoor concentration of a major air pollutant called PM_2.5 periodically hits 20 μg / m³. For background, PM stands for “particulate matter” and is, essentially, airborne dust. The “2.5” stands for particulate matter that is 2.5 microns (μg) or smaller. The size of the particle matters because particles of this size penetrate to the deepest parts of our lungs, the alveoli, where gas exchange occurs. Larger particles are captured by nasal mucosa or the upper respiratory system, where we get rid of them when we blow our noses, or after our lungs bring them up to our mouth via a mucociliary escalator to be harmlessly swallowed. The notation “μg / m³” refers to the mass of PM_2.5, in micrograms, in a cubic meter of air (m³).

What most people don’t fully recognize is the extent to which outdoor air pollution can penetrate inside a home or building.¹⁰ As you might expect, there are a lot of factors that determine just how much outdoor air pollution enters a building, or what we call infiltration factors. Things like the year of construction and leakiness of the building, whether there are operable windows (and whether they open or not), and the type of ventilation and filtration system in your building are the obvious ones, but wind direction, pressure, and other meteorological factors also play a critical role. A review of different infiltration factors in homes shows that a stable median estimate for infiltration in homes is ~50 percent.¹¹ In commercial buildings, which typically use a MERV 8 filter, the PM_2.5 removal efficiency is about the same as this estimate. (MERV stands for Minimum Efficiency Reporting Value, a tool developed to evaluate filter performance.)

Using these facts, and for demonstration purposes, we can take the outdoor air pollution number in our Los Angeles example and estimate that, on average, the indoor concentration of outdoor air pollution is half of that, or 10 μg / m³.

Now we need to figure out how much air we breathe, because ultimately we want to know the total amount of air pollution that enters our body each day, what we call a “daily dose” in public health. We take about 1,000 breaths per hour, and that means we typically breathe in about 0.625 m³ of air per hour, or 15 m³ per day.¹²

Now that we know how much air pollution from outdoors is inside, and how much air we breathe each day, we need to know where we are breathing that air. For that, let’s turn back to our “where we spend our time” data at the beginning of this chapter. Because we spend 90 percent of our time indoors, this means that we spend over 21 hours of each day inside and less than 3 hours outside. (For some of us it will be less than 1 hour.)

TABLE 3.1    The dirty secret of outdoor air pollution.
		Outdoor Air Pollution		Breathing Rate		Time Spent Indoors		Total Outdoor Air Pollution Breathed per Day
Outdoors		20 μg / m3		0.625 m3 / hour		2.4 hours (10% of 24 hours)		30 μg / day
Indoors		10 μg / m3		0.625 m3 / hour		21.6 hours (90% of 24 hours)		135 μg / day

Now, the math is very straightforward. Multiply this out and you’ll see the proof behind the counterintuitive fact that the majority of your exposure to outdoor air pollution occurs indoors. In this example, the amount of outdoor air pollution breathed indoors is four times as high as the amount breathed outdoors. Dirty secret no more!

Every single day, you can find a news story somewhere about how bad outdoor air pollution is in places like Mexico City, Seoul, New Delhi, or Beijing—and it truly can be bad, dangerously so. That news story is typically accompanied by a picture of a parent and young child walking hand in hand outside with dust masks over their noses and mouths, engulfed in a haze of air pollution. But we challenge you to find a news story that talks about what happens when that parent and child go inside. You will never find this “dirty secret of outdoor air pollution” in the news. We look forward to the day when a news story about outdoor air pollution is accompanied by a picture of a family sitting on the couch wearing dust masks. (A public health side note to readers: those paper dust masks don’t actually work against this type of pollution; they’d have to be on their couch wearing an N95 mask.)

Indoor Assault 2: Indoor Sources

In addition to outdoor air pollution penetrating indoors, we also have indoor sources of air pollution. In fact, a frequently referenced estimate from the Environmental Protection Agency says that indoor levels of some contaminants can be 3–5 times higher than outdoors. For many pollutants, the number can rise as high as 10 times or more.¹³

These higher indoor levels of pollutants happen because we tightened up our buildings to limit how much fresh air came in, in our efforts to save energy. Then, after we trapped ourselves in these airtight chambers and became appalled at the odors we started to notice, we started to use sprays, candles, and scented cleaners to make that stuffy indoor air smell just a bit better, without realizing that those sprays can create a whole other set of attacks on our health. And then we doused ourselves in underarm deodorant, cologne, perfume, and scented shampoo so we would smell good in all of these stuffy boxes we created. Not to mention all the building materials and furniture that off-gas pollutants into our sealed-box homes and offices.

There are all sorts of potential indoor contaminants, some of which you may be familiar with, and some of which you probably haven’t thought much about. Perhaps the most well-known indoor contaminants are a class of chemicals called volatile organic compounds (VOCs). As the name suggests, they volatilize, or off-gas, from the products they are in. VOCs are a broad class of chemicals, emitting from paints (the VOCs evaporate, leaving the pigment behind), building materials, surface cleaners, dry-erase markers, furniture, and even dry cleaning. In your home, VOCs also come from laundry detergent, dryer sheets, couches, and soaps. One of the most notorious VOCs, formaldehyde, is a known carcinogen that is used to bind wood together in some cabinetry and laminate flooring that can off-gas into our homes and offices. A high-profile example was an issue with Lumber Liquidators in 2015, when they sold flooring imported from China that was emitting formaldehyde into homes. (In 2019 Lumber Liquidators settled a $33 million lawsuit for misleading investors on this issue.)¹⁴

Another set of infamous VOCs are the BTEX compounds (benzene, toluene, ethylbenzene, and xylene) that come from gasoline. We encounter BTEX when we breathe in our cars, and if your house has an attached garage, the BTEX chemicals can find their way into your home.¹⁵ This also happens in offices and schools when the air intakes or open windows face streets or parking lots. Elevated levels of benzene (and formaldehyde and particles) can be found in schools during the end-of-day pickup time, when school buses are idling adjacent to the building.¹⁶ If you live in a community ringed by traffic corridors—particularly if there is frequent congestion—BTEX chemicals are likely in your life as well.

And then there are the VOCs in personal care products. VOCs emit from perfume, lotion, hand sanitizer, shampoo, and deodorant. A study of high schoolers in Texas by Corsi and his collaborator Atila Novoselac found a VOC signal from one brand of teenage body spray, Axe, in all of the classrooms studied!¹⁷

VOCs also include things like limonene, a sweet-smelling chemical naturally found in oranges that is added to household cleaners to give them a pleasant scent. Sounds innocent enough, but limonene reacts with ozone to form formaldehyde and indoor particles.¹⁸ So not only do we have outdoor sources of particles penetrating indoors, we have our own indoor particle sources, too.

Indoor particle generation doesn’t end with VOCs reacting with ozone, though. We have other indoor sources. Smoking is an obvious one. Candles also emit a steady stream of particles indoors, as does cooking a stir-fry on the stovetop. A research team led by Delphine Farmer and Marina Vance, who simulated particle generation during cooking of a Thanksgiving dinner as part of their House Observations of Microbial and Environmental Chemistry study, found that indoor particle concentrations can be 10 times higher than outdoor maximums.¹⁹

Our bodies are also part of this equation. Just like the Charles Schulz cartoon character, we are all our own little versions of Pigpen. (For those who don’t know the Peanuts comic strip, Pigpen is one of the characters, a prototypical messy kid swirling in his own personal dust cloud.) As we walk, sit on couches, and fold laundry, we resuspend particles that have settled out on surfaces all around us, creating a cloud of invisible particles that surrounds us.

While the main problem comes from breathing them in, pollutants find their way into our bodies through what we eat (ingestion), through hand-to-mouth contact, and even through our skin (dermal absorption). Take this fascinating set of new studies by Gabriel Bekö, Charlie Weschler, and others at the Danish Technical University that asked, “Are we breathing through our skin?”²⁰ The researchers sat for several hours in a room with elevated concentrations of a common indoor pollutant. They were fully stripped down to their shorts, so nearly all of their skin was exposed, but they were breathing “clean” air through breathing hoods that covered their heads. Then they tested their urine to look for the chemical or its metabolites in their urine. A few days later they repeated the scenario, but this time with no hoods, to disentangle the relative importance of the different pathways that chemicals take to get into our bodies. Surprisingly, they found that dermal uptake of some plasticizers (and even nicotine) is as important as the inhalation route. In other words, we are definitely “breathing through our skin.” They also found that clothing can act as a barrier, or as a source. If your clothes have these chemicals in them, they may trap them close to your skin, creating a constant source of exposure over an extended period of time. If the source is somewhere else in the room, a clean set of clothing can help limit that exposure, simply because less skin surface area is exposed.

When we think about buildings and exposure to pollutants, the conversation in the building world tends to revolve around indoor air quality, or IAQ. We see the shorthand IAQ now being used to mean basically any hazard in the indoor environment, and that needs to be corrected. A more apt term that some of us use as a replacement phrase for IAQ is IEQ: indoor environmental quality, which is a bit more encompassing. Here’s why.

In addition to VOCs, there are a whole host of other indoor pollutants to think about and other routes of exposure beyond inhalation. There are things like the heavy metal lead, which can be found in old paint and old water pipes or tracked indoors on our shoes. Lead gets into our bodies through ingestion, as well as inhalation of suspended dust. Or as we saw with the preventable catastrophe in Flint, Michigan, it can get into our drinking water, which we then ingest. The term IAQ does not work here; it’s too narrow.

There’s also an insidious set of chemicals that are used in furniture, carpets, and other products that wreak havoc on our hormone system. (Fast-forward to Chapter 7 if you want more on toxic chemicals from products.) Some of these are what we call semivolatile organic compounds (SVOCs). You might think of SVOCs as multi-talented VOCs—they can be a gas or attach themselves to airborne dust, or they can be in dust on the floor, or on walls, or on our skin or clothing. The scientific term for what we are talking about here is “partitioning.” Where these SVOCs reside in the air or dust depends on their physical and chemical properties and environmental conditions like temperature, humidity, and airborne dust levels.

The multi-talented SVOCs are also clever about how they can get into our bodies—through our lungs, through our skin, or through our GI tract as we transfer small quantities from the surface of our hands to our mouths when we eat with our fingers or touch our lips. We call that transfer of dust via hand-to-mouth contact “incidental ingestion.” And would you ever guess that this “incidental” ingestion can be up to 100 milligrams of house dust per day?²¹ It might make you think about the dust in your office or home a bit differently …

All this is to say that the products we use in our offices, homes, and cars, and the activities we perform there, all contribute to this indoor cocktail that our bodies are constantly absorbing and ingesting. The problem goes beyond IAQ. It’s a question of total IEQ, of which air quality is a subset. And our building plays an important role in creating, or mitigating, these conditions.

Indoor Assault 3: What Is Your Neighbor Doing?

We’ve now talked about two assaults on your health—indoor sources of air pollution and outdoor air pollution coming inside, but indoor health hazards are actually a three-pronged assault for many people. It turns out that even if you do your best to stop outdoor pollutants from penetrating inside and you are super careful about what’s happening inside your own space, there’s another thing to be concerned about. And that “thing” is your neighbor.

Anyone living in a high-rise or multifamily dwelling is all too familiar with the experience of smelling your neighbor cooking. That’s telling you that the air inside the building is communicating between apartments. You might want to ask what your neighbor is doing, because it turns out that in many buildings, on average, 9 percent of the air inside your apartment is coming from a neighbor.²² (If you’re in an older multiunit building, this can be as high as 35 percent.)

Take a good look at your neighbors next time you’re in the elevator or stairwell and ask yourself, “Do I really want to be breathing their air?” If they smoke, you’re smoking. If they have cats, you have cats. If they have laminate flooring that emits formaldehyde, you’re getting a bit of that, too.

This issue of the neighbor isn’t just one to think about for multitenant residential buildings. You can, and should, also think about the word “neighbor” for any space adjacent to yours that can impact your indoor environmental quality. So for a commercial office building, your neighbor could be the building next door. There are many instances of one building’s ventilation exhaust feeding almost directly into the adjacent building’s air intake. When a restaurant exhaust billows up into the adjacent building’s air intake system, it’s noticeable because of the distinct grease smell; if a renovation is happening next door, the smell of freshly cut wood may waft into your building. That’s an indication of just how much air transfer there can be between buildings.

A common example of this problem can be found in buildings whose air intakes are right at street level or by a parking lot. Any idling car in the vicinity of that intake supplies a steady stream of pollutants that gets sucked up by the air intake and efficiently distributed around the building. Take a look around you the next time you walk by a set of buildings in the downtown district in your hometown—you’ll find that, amazingly, the practice of having the air intake close to the street or in a parking lot is not that unusual.

Joe’s favorite example comes from an office building where people noticed an occasional whiff of air that smelled like rats and mice. The owners hired a pest management firm and searched the building but couldn’t find evidence of any pest infestation. After a thorough investigation inside their own space, they could not figure out why there was a rodent smell—until they started looking at their neighbor. It turns out that the air intake for their building was in an alley and the exhaust air for the adjacent building was feeding into that same alley. That second building happened to be the home of an animal toxicology program with many hundreds of … mice and rats.

Understanding Risk

With this three-pronged assault on our health, you might be forgiven for thinking that all is lost and you should spend the rest of your life living in the mountains or in a hermetically sealed bubble. That’s not necessary. There is good news here: your building can actually help mitigate the impact of this assault.

To understand how these assaults may impact us and how our buildings can help requires that we understand the basic concepts of exposure science—that is, we need to know how the concentration of a pollutant, the duration of exposure, and the frequency of that exposure can combine to create an adverse health effect—and then figure out how to intervene to stop that from happening.

Take the example of the short, infrequent exposure to the BTEX chemicals while filling your car’s gas tank. You can be exposed to a high concentration of benzene while you are filling up at a gas station, but the overall risk is quite low because the duration of that exposure is brief and infrequent. (If you have an electric vehicle, it’s never. If you’re a worker at the gas station, that’s another story altogether.)

Using the Building to Break the Chain of Exposure and Risk

In public health, when we try to understand the different building factors that influence health, one useful model to consider is what we call the “conceptual model for exposure-related disease,” first introduced to Joe by one of his doctoral thesis advisers, Michael McClean, now associate dean at Boston University School of Public Health. (We promise to make this part interesting, but we’re academics, so we have to talk about conceptual models too. Bear with us; this will be useful to you.)

This model is great because it is really simple in concept and really useful in practice. As we work from left to right, we move from sources of pollutants in buildings to personal exposure to those pollutants to potential health effects, with a couple of steps in between. Why is this useful? If we break the chain before personal exposure, we have eliminated or at least minimized the risk of a downstream health effect. A key aspect of this model that’s right in the name but needs to be highlighted anyway is that this model is about exposure-related disease, not other factors that influence health, such as genetics, which is why it’s so relevant to our buildings. This is all about the environment. And that’s why and how buildings can be used to break that chain.

FIGURE 3.1    Conceptual model for exposure-related disease.

Let’s go through an example and walk through the various subboxes to make it clear. And to make it interesting, we will use a high-profile case from a few years ago.

“What’s Lurking in Your Countertop?”

In 2008 the New York Times published a story with the alarming title “What’s Lurking in Your Countertop?” The story started a national scare by “breaking” the news that granite countertops can emit radon.23 What’s radon and why should I care, you ask? It’s a radioactive gas that is commonly reported as the second leading cause of lung cancer.

Radon is a ubiquitous gas that forms from the natural decay of uranium from granite in the ground. It’s a hazard that we think about mostly in relation to our homes, as it can permeate through the soil and find its way into our basements through cracks and fissures, and then to the rest of the house, where we spend our time. The New York Times story taught us that another source of radon indoors was granite in people’s homes.

Radon is interesting from a risk perspective because, unlike for other environmental pollutants, we “accept” an unusually high level of risk for radon. To put numbers on this, whereas the Environmental Protection Agency regulates other pollutants to keep risk at 1 in 1 million (10⁻⁶ risk, spoken as “ten to the minus six”), the goal is to keep radon below 4 picocuries per liter of air in our homes, a level associated with a nearly 1-in-100 lifetime risk for lung cancer for nonsmokers (10⁻³) and a truly astounding nearly 1-in-10 risk for smokers (10⁻²). In short, we “accept” a much higher level of risk for radon than we do for other environmental pollutants.

Back to our conceptual model for exposure-related disease, where we’ll use radon to explain the other boxes in the model. The source of radon, as that New York Times article pointed out, is the granite countertop. The next step in our model is environmental media, which is the annoying public health way of saying air, water, or dust. Radon is gas that is emitted from the granite countertop (the source) into indoor air (the environmental media).

Next up in the model is micro-environments. This is our way of saying where you encounter the pollutant. Most of the time granite is used in the kitchen in a home, but the gas migrates around the home, so the different micro-environments where you could encounter radon are places like the kitchen, your bedroom, the basement, and even outdoors. This is critical, because understanding risk requires you to understand the different micro-environments where we are exposed.

If we want to figure out the next part of our model, personal exposure, we need to match up where we spend our time (the micro-environments) with the concentration of the pollutant in air (the environmental media). It’s all very logical if you step back from the terminology for a minute—a pollutant can’t have a meaningful impact on our health if we rarely encounter it (the BTEX at the gas station, for example).

In the radon from countertops example, you would rightly anticipate that the personal exposure concentration would be highest in the kitchen, where the source is. But what are the frequency and duration of that exposure?

To figure that out, we go back to “where we spend our time” and learn that we spend about 2 percent of our time in the kitchen and 34 percent of our time in the bedroom. So while the radon concentration may be highest in the kitchen, the duration and frequency of exposure there may be quite low.

An interesting side note to get you thinking about the role of the building here: In homes with central air-conditioning, the radon concentrations aren’t that much higher in the kitchen than in the rest of the house, even though that’s where the countertops are. Why? It’s because these central air-conditioning systems draw air from all areas of the home, cool it, and then redistribute that cooled air evenly around the home. Essentially, the central air-conditioning takes that higher radon concentration in kitchen, mixes it with air from everywhere else in the home, and then spreads that mixed air around the home. The result is lower radon in the kitchen but higher radon elsewhere. This makes that time in the bedroom more consequential from an overall exposure standpoint because the central air takes some of that radon from a place where we don’t spend much time and delivers it to a place where we spend a good portion of our time. (This same thing happens often in commercial office buildings, hospitals, and schools, where the ventilation system sometimes acts as an efficient system for distributing a pollutant all around the building.)

Now that we understand the elements of the left side of this conceptual model, it’s easy to target our interventions. If you wanted to lower your personal exposure to radon from countertops, you could remove the source, attempt to lower the pollutant concentration in the air (environmental media) through filtration or building-ventilation strategies, or reduce time spent in different micro-environments. In fact, you must use this model when thinking about a building-related exposure. All too often, the mere presence of a potential hazard is used to say there is risk, without understanding how that potential hazard migrates out of the source and creates exposure.

(The right-hand side of the model goes beyond the scope of this book, but it covers what happens to pollutants after they enter our body. In Toxicology 101, this is described by the handy acronym ADME [absorption, distribution, metabolism, and excretion]. The penultimate box in the model is altered structure and function, which is the way we highlight that it’s not always enough to have an absorbed dose [the amount that enters the body]. Rather, that absorbed dose has to lead to some altered structure or function of one of our biological systems to have the potential to cause a health effect.)

So What’s Lurking in Your Countertop? Nothing

We didn’t think it was right to end this chapter without telling you what happened with the radon-in-granite-countertops scare. Joe led the team that was hired to work on this project after the New York Times story broke, performing a series of investigations with colleagues in his former consulting company.

The ensuing forensic investigations essentially followed this conceptual model of exposure-related disease, beginning with measuring the emissions, or flux, of radon from the countertops into air in the home. Sure enough, the testing confirmed that some granite countertops can emit radon.

And this is where the New York Times story failed. It essentially reported this finding, that radon comes out of granite countertops, without taking into account the rest of the conceptual model. Had the “expert” the reporter interviewed done so, he would have figured out what Joe and his team did when they simulated 1 million granite countertop purchases and installations, accounting for things like varying ventilation rates in homes and where people spend their time. They found that 99.99 percent of scenarios generated radon levels that were below what’s typically found in US homes from radon coming from the ground. The formal conclusion in the peer-reviewed paper: “The findings presented in this study demonstrate that the probability of a granite countertop leading to a meaningful radon exposure in a home is negligible. These de minimus risks would be considered acceptable based on risk limits used by the EPA in regulating potential environmental hazards (10^-5–10^-6).”²⁴

So if you were thinking about ripping out your granite countertop, think again.

The Opportunity Moving Forward

So far we’ve aimed to make it clear that the buildings where you spend your time have an impact on your personal health. In Chapter 4 we will discuss specific steps you can take to optimize for health and performance, and we’ll show you how this directly translates to bottom-line performance.

Here’s what’s at stake: In the preface we mentioned that $7 trillion in real estate institutional capital tracks green building performance, and as of this writing, there are over 100 green building councils around the world and millions of square footage of office space certified as green. In this chapter we showed the massive opportunity in front of us when we begin to shift from thinking about green buildings (which largely focuses on the 1 percent of costs associated with energy, waste, and water) to thinking about Healthy Buildings (which focuses on the 90 percent of the costs of our buildings—the people). John Mandyck, the former chief sustainability officer at United Technologies and now CEO of Urban Green Council, has put the challenge succinctly: “Can you imagine how much farther and faster we can go when we start to focus on health?”²⁵

In Chapter 4, we will do exactly that—we will show the quickest, easiest way to unlock the power of buildings to drive health and wealth.