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The Hidden Air Pollution In Our Homes

Food magazines typically celebrate Thanksgiving in mid-July, bronzing turkeys and crimping piecrust four months in advance. By that time last year, Marina Vance, an environmental engineer at the University of Colorado Boulder, had already prepared two full Thanksgiving dinners for more than a dozen people. Vance studies air quality, and, last June, she was one of two scientists in charge of Homec hem, a four-week orgy of cooking, cleaning, and emissions measurement, which brought sixty scientists and four and a half million dollars’ worth of high-tech instrumentation to a ranch house on the engineering campus of the University of Texas at Austin. The two Thanksgiving dinners were the climax of the project and represented what Vance called a “worst-case scenario.” She suspected that the Pilgrims’ harvest celebration, as it is observed in twenty-first-century America, qualified as an airborne toxic event.The morning of the second simulated Thanksgiving began simply enough, with the researchers making themselves breakfast. Vance and three helpers arrived at the house at half past eight. The kitchen was open plan and modest, with peeling laminate surfaces and flimsy cabinets, but its countertops were crammed with instruments for monitoring airborne particles: a condensation-nucleus counter, a differential-mobility analyzer, and so on. Wires threaded all around the room, and stainless-steel hoses led to four trailers outside, which contained equipment too big to fit in the kitchen.Andrew Abeleira, a postdoctoral researcher, cracked eight eggs on the edge of the countertop and whisked them; Vance chopped tomatoes while heating oil to fry sausage patties. The banality of the activities was belied by the precision with which the team carried them out: a rigid protocol dictated when each gas burner could be lit, how hot the frying pan should be, and at what setting to toast the bread. The aim was to turn Thanksgiving into a reproducible, scientifically valid experiment.Tapping a pair of tongs on the cooktop, Vance wondered aloud whether it was nine-twenty yet, the appointed time for switching on the coffeemaker. “Oh, shoot, toast!” she exclaimed, popping two slices of honey-wheat in the toaster. A minute later, a student volunteer named Caleb Arata, looking at data on his laptop, announced a spike in the presence of so-called volatile organic compounds. The term describes any carbon-based chemical that evaporates at room temperature, and it encompasses a huge variety of molecules, emitted both by plants and by human activities. VOCs are responsible for much of what we smell—toast, flowers, gasoline—although some have no odor at all. And, while certain of them, such as benzene and toluene, are known to be harmful when inhaled, for the most part their health effects have not been studied.“The scariest thing in this house is probably the toaster,” Erin Katz, another student volunteer, said. “I just had no idea that toasters emitted so many particles.”After breakfast, the serious work began: peeling sweet potatoes, trimming Brussels sprouts, simmering turkey parts to make a stock for gravy. Culinary ambition had not been sacrificed to scientific rigor: Arata had spatchcocked the turkey and dry-brined it for two days; Abeleira tossed the sprouts in balsamic dressing; Katz downloaded a recipe for sweet-potato casserole from a foodie Web site. The oven stayed on for five hours straight, the burners in constant rotation. Vivaldi’s “Four Seasons” played from a Bluetooth speaker, and the four cooks began to sweat, the air-conditioning system unequal to all the activity.While stirring, scrubbing, and basting, the cooks darted back and forth between the kitchen and their laptops, in the dining area. Every action, however seemingly inconsequential, had to be logged: opening the oven door, changing the trash bag, even a bout of sneezing. At 1:37 P.M ., the team briefly debated whether to set fire to an oven mitt; one had accidentally caught light at that time during the previous Thanksgiving, and, as responsible scientists, they were keen to insure that the data sets from the two days matched. Eventually, they decided that the integrity of their experiment wouldn’t be fatally compromised if they failed to sacrifice a second mitt.The conversation turned into a kind of play-by-play pollution commentary. When Vance peeled an orange for the cranberry sauce, Arata noted that its fragrance—that is, its monoterpene VOCs—had made the readings on his instrument soar. Abeleira, checking levels of nitric oxide and carbon dioxide during a brief lull before the turkey went in, observed, “They’re orders of magnitude higher than outdoors.” It was the same for fine particulate matter—particles small enough to reach deep inside our lungs. By around eleven o’clock, the fine-particulate concentration had risen to such a level that, if the house were a city, it would have been officially labelled polluted. Concentrations peaked when the stuffing, and, later, the pies, came out of the oven. And, for nearly an hour, fine particulate matter was within the range that the Environmental Protection Agency’s Air Quality Index defines as “very unhealthy.” If outdoor air reaches these levels, a public alert is triggered, warning that even healthy individuals are at risk of serious damage to the heart and lungs.These days, a “very unhealthy” designation for outdoor air is rare. After the passage of the Clean Air Act, in 1963, and the creation of the Environmental Protection Agency, in 1970, the chemical composition of outdoor air became federally regulated, with penalties for polluters. Since the seventies, emissions of many harmful gases, such as carbon monoxide and sulfur dioxide, have fallen by half, and particulate counts by eighty per cent. But this victory may be less significant than we assume, because, in America, we spend, on average, ninety per cent of our lives indoors. (By way of comparison, this means that humans spend more time inside buildings than sperm whales spend fully submerged in the ocean.) The statistic, from an E.P.A.-funded study conducted in 2001, might seem implausible, but it probably understates the case. More recent data, from the U.K., show that, on average, Britons are outside for just five per cent of the day—an hour and twelve minutes.Unlike outdoor air, the air inside our homes is largely unregulated and has been all but ignored by researchers. We know barely the first thing about the atmospheres in which we spend the vast majority of our time. Homec hem—House Observations of Microbial and Environmental Chemistry—was the world’s first large-scale collaborative investigation into the chemistry of indoor air. Thoroughly dissecting the data accumulated will take a couple of years, at least, and, even when the findings are published, no one will be able to state their public-health implications with certainty; Homec hem was designed to explore what the chemistry of indoor air is, not what it’s doing to us. But the experiment’s early results are just now emerging, and they seem to show that the combined emissions of humans and their daily activities—cooking, cleaning, metabolizing—are more interesting, and potentially more lethal, than anyone had imagined.In September, 1776, Congress sent Benjamin Franklin and John Adams on an ultimately fruitless mission to Staten Island to negotiate peace with the British. One night, the two shared a room at a country inn, an adventure recorded in Adams’s diary. Adams, “who was an invalid and afraid of the Air in the night,” shut the window. To which Franklin responded, briskly, “The Air within this Chamber will soon be, and indeed is now worse than that without Doors: come! open the Window and come to bed, and I will convince you.”According to the architectural historian David Gissen, debates about the relative dangers of household emissions versus urban emissions, and indoor air versus outdoor air, have swung back and forth between Franklin’s and Adams’s positions ever since, depending on each era’s prevailing beliefs and concerns. In 1867, inspired by the miasmatic tenements of America’s burgeoning cities, the engineer Lewis  W. Leeds delivered a series of lectures under the title “Man’s Own Breath Is His Greatest Enemy.” He warned the unwary that “it is not in the external atmosphere that we must look for the greatest impurities, but it is in our own houses that the blighting, withering curse of foul air is to be found.” Half a century later, by contrast, the modernist architect Le Corbusier saw the indoor environments he designed as beneficent bubbles of man-made weather, shielded from the smog-choked city outside.In mid-century America, cities such as Los Angeles and New York were repeatedly shrouded in thick brown fog—sometimes so lung-burningly toxic that it was mistaken for a chemical-weapon attack by a foreign power—and air pollution became an urgent issue. Legislation to curb it began appearing in the U.S. and other countries in the nineteen-fifties. After the passage of the Clean Air Act, government research dollars flowed to scientists looking to understand and to mitigate the sources and the health effects of air pollution. But there was still almost no funding available for research into indoor air. Charles Weschler became one of just a few scientists in the field when he went to work for Bell Labs, in 1975, soon after completing a Ph.D. in chemistry. The company had noticed that the equipment in its telephone switching offices was failing faster than expected; it turned out that wire relays were being eaten away by an acidic, invisible indoor smog. Weschler told me that the little indoor-air research that was being done at the time was mostly geared not toward protecting people but toward preserving things.In the eighties, amid emerging concerns about “sick-building syndrome,” a nonspecific malaise reported by occupants of the era’s new, more tightly sealed buildings, the E.P.A. started measuring indoor concentrations of known toxins, such as formaldehyde and asbestos, and assessing where they came from (paint, floor coverings, upholstery, particleboard). Researchers found that concentrations of these compounds were consistently higher indoors than they were outdoors, and some states began regulating consumer products containing the contaminants.But it wasn’t until the aftermath of 9/11, with its heightened fear of airborne biological attacks, that indoor-air research finally attracted some funding—from the Alfred P. Sloan Foundation, one of the largest private grant-making nonprofits in the U.S. (Among its many grantees is a podcast I produce.) Through a program managed by Paula Olsiewski, a biochemist by training, Sloan began supporting research into H.V.A.C. filtration systems. Olsiewski identified a major difficulty in detecting traces of biological weapons: a complete lack of knowledge about the typical, baseline conditions inside buildings. As she put it to me, “If the biological threat was a needle in the haystack, what’s in the haystack? What microbes are in the air, and in the rooms, and on the surfaces?” She launched a multimillion-dollar program to investigate the microbiology and, later, the chemistry of our built environment.Because there were so few specialists in the area, she decided to use Sloan money to lure eminent atmospheric chemists indoors. Delphine Farmer, a chemist based at Colorado State University, told me that, when she was invited to attend a workshop on indoor air chemistry in France, in 2015, her initial reaction was “You know, sure, I’ll take a free trip to France.” Farmer had spent the bulk of her career developing ways to accurately measure extremely tiny amounts of very complicated airborne molecules. She knew little about indoor air, but assumed that it wouldn’t be of interest. Outdoors, primary emissions—whether from tailpipes, factories, or fertilizer-laden farms—undergo near-constant transformation into new combinations of chemicals through a cascading sequence of reactions. Indoor atmospheres were widely assumed to be far more static. But Farmer was captivated by the presentations that she heard. “I realized that we know nothing about indoors from a chemistry perspective,” she told me. “It was very clear that it was an area that was ripe for study, and that the indoor community just hadn’t had the resources we have in outdoor atmospheric chemistry.”Olsiewski asked Farmer to lead an initiative to develop new instruments and databases for the study of indoor atmospheric chemistry. She recruited Marina Vance around the same time, hoping that the pair could build networks among researchers in the field. Vance and Farmer decided that the best way to achieve both goals was to initiate a large field study. Collaborative field studies are common in outdoor atmospheric research, because capturing the diversity and the complexity of the chemistry involved requires more instruments and more varied expertise than one lab can muster, but nothing of this scale had ever been undertaken indoors. Farmer and Vance gathered twenty research groups from thirteen universities, and Homec hem was launched.At the University of Texas at Austin, the UTest House sits in a corner of the J. J. Pickle Research Campus, a scrubby four-hundred-and-seventy-five-acre plot of land dotted with radio antennae, a prototype nuclear reactor, and one of the nation’s largest nonmilitary computers. Atila Novoselac, the building engineer who runs the house, drove me there, pointing out the local landmarks before parking next to a jumble of weathered concrete chunks, which a structural-engineering lab was using to study the aging of pillars that support bridges and highway overpasses.The house, a twelve-hundred-square-foot prefab that cost sixty thousand dollars, has been on the campus since 2006. Novoselac signed the contract to buy it on a Monday, and the house, delivered in two halves that were then glued together, was ready by the end of the week, complete with kitchen cabinets, bathroom fixtures, vinyl flooring, and curtains so ugly that he removed them immediately. In the years since then, for various research projects, Novoselac and his colleagues have cut the house open, studded it with thermal sensors, and pumped it full of gases. Novoselac says that although it is fully operational as a house, he doesn’t think of it as one: “It’s a tool, a piece of equipment—the same as a screwdriver or a sensor.” Nonetheless, over the years it has been decorated with a doormat that says “hello” in looping cursive, a wobbly floor lamp, and a selection of scientific posters detailing research that has been conducted there.By the time that Delphine Farmer and Marina Vance were looking for a site to host Homec hem, the UTest House was so dilapidated that Novoselac was contemplating scrapping it. But, as one of only a handful of full-scale test homes in the country, it was a perfect place to conduct a full-scale simulation of human inhabitation. Vance and Farmer devised a schedule that would organize real-life activities—cooking, cleaning, and simply hanging out—into a series of controlled, sequential experiments.When I visited the house, two doctoral students, Catherine Masoud and Kanan Patel, made us all stir-fry for lunch, while Novoselac used an ultrafine-particle counter to monitor the air quality. The instrument, which looked like a clunky blue plastic car phone from the eighties, complete with telescoping aerial, recorded a background level of around two thousand particles per centimetre cubed before the cooking began. Patel pulled up the project’s stir-fry spreadsheet on her laptop, turned the right-front burner to its highest setting, and set rice to boil in a small pot. Masoud warmed up a couple of tablespoons of oil in a wok, dumped in two bags of frozen vegetables, and stirred them over a high heat. As the broccoli and the sugar snap peas started to caramelize, the smell from the kitchen made my stomach rumble, and Novoselac’s particle counter emitted an accelerating series of beeps. “That sound means w ...Read more

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