 We know that poor indoor air quality and office environments can adversely affect the health and well-being of office workers. Elevated levels of indoor air pollutants and stale air cause fatigue, irritation of the airways, headaches. So we want to provide better air quality for office workers to improve their productivity. One of the first steps in doing that is to understand what's in the air. We're at the Ray W. Herrick Laboratories at Purdue University where we do research on buildings and building ventilation systems. We're doing a project here in the Living Laboratories and the Living Laboratories are four occupied office environments. They're very precisely controlled. We're tracking what's going on in terms of how the air moves throughout the ventilation system, how it is heated and cooled, and also how many people are inside the office space. So this is a proton transfer reaction time-of-flight mass spectrometer and it's basically like a highly sophisticated nose. It allows us to sniff the air and see all the volatile organic compounds that are in the air and it does this in real time second by second. We can see compounds that are released from people through their exhaled breath also the personal care products that they wear in their bodies such as deodorant as well as building materials and furnishings. We just saw a huge spike in the concentration of monoturpeans. They're associated with the odor of orange or lime or lemon. Likely somebody peeled an orange or mandarin in the common area outside of the office. So this valve system allows us to track how the concentrations vary in space. Each of these Teflon tubes go to different sampling locations in the ventilation system and then we switch these different locations, we sample the air at that location and then we can see how the building ventilation system affects the dynamics of these indoor air pollutants. There's 12 occupants max at a time. Students have classes so they come and go but generally in the afternoons there's a lot of people and we want to look at how the people affect the air related to the VOCs and the particles. To see the occupancy in each seat we have thermocouples that measure when people are there because they sit down and temperature shoots up and then they stand up and it spikes down so we can get the spatial map of the room when people are in it. Okay so we have several aerosol instruments to measure the particular matter concentration in the air handling unit. The outdoor air and the return air from the office will mix here and the air goes down. First it will pass through the filter. In the first bank of the chamber we have two instruments to measure the filtration efficiency of particles upstream and downstream of the filter. By using the data here we can figure out the filtration efficiency of the air handling unit. So here it means the concentration is high. It's from the upstream of the filter and here is the low concentration from the downstream of the filter. So one finding that we have made is that people drive a lot of the chemistry of the indoor environment and we can see that with the different levels of occupancy that we're monitoring and then throughout the day the occupancy is constantly changing and we can see how that occupancy drives the amount of indoor air pollutants in the office environment. Another take away is that building ventilation can have both a positive effect on indoor air quality and a negative effect. So when we deliver outdoor air to the office space we can dilute the concentrations of pollutants that are generated inside the building but it can also deliver a lot of outdoor ambient pollutants indoors. These include ozone and ambient particulate matter. So there's a trade-off there that we have to be aware of. One thing we can do to purify the outdoor air is pass it through high efficiency filters but we have to be aware of how changing the ventilation and the amount of ventilation affects the indoor air quality. With this project I hope that we can provide better guidance on how to properly operate a building ventilation system to provide better air quality for office workers in an effort to improve their health and well-being.