AUB research: the Air We Breathe
Rawad Saleh, a doctoral student at Duke University, spent his summer working with Professor Alan Shihadeh measuring airborne particles in search of answers to a controversial question facing the global climate and regional air quality modeling community: how to achieve accurate air quality measurements.
Saleh writes: "Particles in the air, referred to as ambient/atmospheric aerosols, pose significant health hazards, including respiratory and cardiopulmonary diseases, and cancer. They also impact the earth's climate by absorbing or scattering light. Scientists rely on air quality models to predict how these particles evolve, and thus assess their impact on the environment; for these models to work, we have to measure the thermodynamic properties of the compounds comprising the aerosol particles (how these compounds partition between the particle and gas phase as ambient temperature, humidity, and gas concentrations). We assess these properties through direct ambient measurements of the atmospheric aerosols and laboratory experiments.
Unfortunately, due to the limitations of the measuring techniques, so far scientists have been forced to assume "ideal kinetics" when taking measurements, which compromises the validity of the thermodynamic properties we're looking to measure. In my current work with the Department of Environmental Engineering at Duke University and the Aerosol Research Lab at AUB, we are developing a new technique that allows us, for the first time, to measure the kinetic properties of the aerosols in order to be able to relax the "ideal kinetics" assumption and obtain better estimates of the thermodynamic properties.
Also working with Professor Shihadeh (and Chemistry Professor Najat Saliba), FEA student Marc Helou's task focused on a problem very close to Lebanese hearts: Effect of Diesel Electrical Generators on Household Exposure to Airborne Carcinogens.
Marc writes: In many developing countries where the capacity for power generation is limited, governments install rotating power shortage systems, cutting supplies between two and 16 hours a day. The aim is to reduce pollution and electricity production costs, but is that what is actually happening? In Lebanon, for example, electricity shortages have forced people to tap into local power production facilities in the form of building generators or by buying into a shared supply from nearby diesel-powered electric generators. In this potent combination of weak environmental regulations and densely packed high-rise buildings we believe there is a serious possibility of high levels of human exposure to airborne carcinogens in the vicinity of the generators.
To determine whether this is the case, we monitor hazardous diesel combustion emissions known as particle-bound polycyclic aromatic hydrocarbons (PAH) and ultrafine particulate matter (UFPM) on balconies of apartments located in the vicinity of one or more diesel-powered electricity generators. At every site we record electricity shortage times and variations in PAH and UFPM levels over a 10-day period. By using a real time monitoring approach, we can establish a relationship between pollutant levels and the time of day when the diesel generator was operating. Our preliminary data indicates that depending on the weather conditions and location, households may experience an elevated daily exposure of up to seven times the normal urban background level due to the operation of a nearby generator.
