Given that we spend 90% of our time inside, indoor air quality can have a major impact on our health. Poor air quality has been linked to a rise in cardiovascular and upper respiratory diseases and an increased risk of mortality. Outdoor air has traditionally been the greater worry, and regulations like the Clean Air Act have led to extensive studies in the field. But indoor air remains underexplored; there is much about its fundamental chemistry and physics that is not well studied. This is a huge concern, as we are surrounded by a chemical cocktail, often shaken and stirred by ourselves, of indoor air pollutants that can affect our well-being and productivity.
At the Purdue Herrick Living Laboratories, we are exploring the factors that contribute to indoor air pollution in one of four identical 34' × 37' open-plan office spaces, each configurable to simulate different types of indoor environments. Here, every environmental aspect can be carefully and individually controlled, compared and examined. For example, we recently conducted a large-scale measurement study of air quality using state-of-the-art instrumentation to investigate how people and ventilation systems drive the chemistry of office environments.
A surprising discovery is that we identified people themselves as a key source of chemical pollutants in office spaces. Our bodies are constantly off-gassing hundreds of volatile organic compounds (VOCs) due to metabolism (the chemical reactions that take place in every living organism as part of sustaining life), chemical reactions on our skin, and personal care products. The human body contains loads of chemical compounds — and when you add items like deodorants, shampoos, and perfumes to the mix, the number and variety increase dramatically.
For example, in an open-plan office with a high density of workers in one room, people can have a significant influence on air quality. Our metabolism rates also affect the human contribution to air quality — for example, a gym where people are sweating will present a different challenge than an office where people are relatively sedentary. Similarly, smokers will register a different profile than nonsmokers. Even an individual’s skin can make a difference, introducing more variables. For example, ozone can react with skin oils to create compounds that alter air quality.
While we are not yet able to pinpoint each person’s individual signature and contribution, we can track the composite signature of a group of people in a room. Because occupancy levels vary throughout the day, we are exploring how VOCs, biological particles, carbon dioxide and other air quality indicators fluctuate at different times during working hours. This process is dynamic and transient, and very challenging to accurately measure and trace.
Our research can help in the design of office buildings that promote optimal indoor air quality for their occupants. Today, the Internet of Things (IoT) — where sensors are embedded in everyday objects — lets us track a variety of contributing factors. If we can understand how occupancy affects office air quality, we can use low-cost IoT sensor readings to capture air quality data to precisely calibrate and continuously adjust the heating, ventilation and air conditioning (HVAC) processes and settings that will improve the air that we breathe indoors.
But before we get there, we have to understand the multiplicity of interactions between a host of factors — including the contributions by people, which might be the biggest factor of all. A clean indoor working environment is the ideal that our ongoing research aims to achieve.
By Dr. Brandon E. Boor, Assistant Professor of Civil Engineering and Environmental & Ecological Engineering (by courtesy), Center for High Performance Buildings, Ray W. Herrick Laboratories, Purdue University College of Engineering
Listen to Brandon Boor on Science Friday: How People Pollute the Workplace
Watch NSF 4 Awesome Discoveries, from the National Science Foundation
Read the Environmental Protection Agency’s guide to improving indoor air quality
Learn the Occupational Safety and Health Administration’s answers to frequently asked questions about workplace air quality