August 29, 2012 — In 2008, architect Tariq Qaiser was in the process of designing tuberculosis (TB) clinics in Pakistan. During that time, he took an intensive two-week course at Harvard School of Public Health (HSPH) on airborne infection control, hoping to get tips on how to devise the best design.
“By the end of the flight home,” said Qaiser, “I’d torn up all of the plans and started from scratch.” The technical knowledge, techniques, and strategies he learned at HSPH had given him new insights into how to build the clinics with airflow and ventilation systems that minimize the spread of the highly infectious disease.
The nearly 40 students who participated in this summer’s Airborne Infection Control program at HSPH—architects, engineers, doctors, nurses, and public health workers from around the world—are, like Qaiser four years earlier, hoping to return to their home countries armed with strategies to reduce the spread of TB and other airborne infections. They came from Spain, Philippines, France, Romania, Colombia, Germany, Russia, and 13 nations in Africa.
Ventilation and air disinfection
“Building Design and Engineering Approaches to Airborne Infection Control,” offered through HSPH’s Executive and Continuing Professional Education program, is now in its fifth year. The brainchild of the late Professor Emeritus Melvin First, an internationally recognized expert in air cleaning and ventilation, and Ed Nardell, associate professor in the Departments of Environmental Health and Immunology and Infectious Diseases, the course has drawn nearly 190 students from 54 countries since its inception. The course offers participants a wide range of technical expertise on ventilation and air disinfection to help contain airborne diseases like TB, the H1N1 virus, the flu, SARS, bioterrorism agents, and even the common cold. Students learn strategies they can use in places like hospitals, clinics, labs, jails, homeless shelters, refugee camps, airplanes, and ships, and that can work in both resource-rich and resource-limited settings.
“This is an important course because people don’t think about airborne infection that often and don’t truly understand the techniques to minimize it,” said Paul Jensen, a course co-director and instructor who leads TB control efforts at the U.S. Centers for Disease Control and Prevention.
After a week-and-a-half in the course, Serge Emalau, a physician specializing in infectious diseases at the Cameroon Department of Health, agreed. “I work with HIV and TB patients, and I had no clue about air control, airflow, how to manage intake and outtake,” he said. “Now I’m well prepared and will be able to share this information with my colleagues.”
Tuberculosis control strategies
Unfortunately, there’s a history of TB spreading in hospital wards, usually due to unsuspected cases or unsuspected drug resistance, Nardell explained in a July 30 course session. Unlike many bacterial and viral illnesses, disease is spread by airborne particles known as “droplet nuclei.” The droplet nuclei concept emerged in the 1930s, pioneered by HSPH researcher William Wells and Richard Riley of Harvard Medical School. Wells and Riley suspected that these microscopic particles, which enter the air when people cough, sneeze, speak, or sing, were a major cause of the spread of certain infections. The particles are light enough that they can float in the air indefinitely instead of falling to the ground like larger particles. Because of their small size, they can penetrate to the deep alveolar level where they infect alveolar macrophages, ironically, the very cells intended to protect us from infection.
To minimize the risk of transmission, ensuring that TB patients are promptly detected and started on effective treatment is critical, Nardell said. But given the difficulty in detecting every case and every case of drug resistance, it’s just as important to minimize the hazard posed by droplet nuclei—and that’s where the expertise of architects, building planners, air quality experts, and personnel in hospitals and other large institutions plays a major role.
Another instructor for this year’s course—Grigory Volchenkov, chief doctor at a TB clinic in Vladimir, Russia—was also, like Qaiser, a former student. He said that after his hospital started using the airborne infection control techniques he learned at HSPH, TB transmission between patients dropped dramatically. Since then, Volchenkov created his own course in Russia based on the one at HSPH.
Low-tech, low-cost solutions
Commode Dushimimana, an architect with MASS Design Group in Rwanda, said he picked up some surprising and inexpensive tips at this year’s course. He learned, for instance, how to make a vaneometer—a device that measures airflow—out of paper, tape, and tissue. “That’s really low-tech,” he said.
Alina Munkawa, an occupational health and safety officer at the Namibia Institute of Pathology, summed up her HSPH experience this way: “We learned that you don’t really need a lot of investment or technology to have good ventilation or the proper air pressure in a room. You just need the proper design.”
photo: Aubrey LaMedica