Earlier this year I met an architectural engineer whose frequent business trips to China spurred an impromptu experiment. From Chicago to Beijing and back, he took regular air quality measurements with a handheld, professional-grade monitor. His readings turned heads, especially on the airplane, but what piqued the most interest was the data set he gathered.
He looked for particulate matter—microscopic solids and liquid droplets suspended in the air. PM 10, about 1/5 the width of a human hair, can gunk up lung tissue and aggravate breathing problems. With the even smaller PM 2.5, those problems are even more acute. On the streets of Beijing, readings regularly exceeded an air quality index of 500—beyond the chart’s highest rating of "hazardous." For PM 10, some street readings were on par with readings taken back in Chicago while standing next to a smoker.
China’s bouts of atrocious air quality are no secret. In January, Beijing’s “airpocalypse” grabbed headlines and upped public pressure on the issue. There is even an iPhone app that tracks the Chinese air quality index. (One reviewer raves, “Great app that allows me to determine if it is prudent to exercise outside!”) Urban centers in India and the Middle East face a similar challenge.
But this engineer’s readings were telling in another way. In controlled environments—inside the airplane, a Beijing cab with the windows up, a new office tower—particulate matter readings dropped dramatically, at times almost to zero. Indoor air quality, the engineer concluded, is a pressing design challenge.
“Use a different set of eyes and you see a whole different city,” he said. “You see a whole different world in buildings, too.”
Carpet floors, for example, emit more particulate matter than bamboo flooring. But the difference diminishes six feet above the floor. Elevation reduces the concentration of particulate matter pollution, too, but not at a constant rate. Broader solutions to particulate matter levels in the general environment are beyond the scope of any single project, but controlling air quality in the built environment is a design frontier ever more important in a continuously growing and urbanizing world.
Unfortunately, indoor air quality is often addressed through compliance with minimum code requirements. But not always; some solutions double as interior design centerpieces. A landscaped green wall covers 1,420 square feet of the Edmonton International Airport in a kind of living art installation whose 32 species of plants humidify and clean the air. Drexel University boasts the largest “BioWall” in the U.S.—a 22-by-80-foot swath of plants that is actively integrated into the building’s air handling system.
Other interventions are less flashy, but no less important. The proliferation of low-VOC materials and efficient ventilation systems, for example, has steadily improved indoor air quality. Beyond piecemeal approaches, there are alternative metrics. Both Passive House and Living Building Challenge standards integrate design and up the ante for indoor air quality.
Not surprisingly, the highest concentration of particulate matter in China occurs in the east, where the concentrations of coal plants and dense urban environments are greatest. Burning fossil fuels remains the ultimate source of much of this particulate matter pollution. Architects have no direct control of that industry. But they can improve the built environment every day.
