For most of us, thoughts of air pollution evoke images of billowing smoke stalks or a miasma of smog blanketing cityscapes. EPA research however, indicates that indoor air pollutants are generally 2-5 times greater than outdoor levels.
The dramatic increase in the cost of energy during the 1970s and an uncomfortable dependence on foreign oil made energy conservation a national priority. Because buildings account for ~40% of energy consumption in the US, much of the conservation measures were directed toward energy use in buildings and homes.
This changed building practices. Airtight designs promised energy efficiency. Air exchange rates dropped from about 1 air change per hour (ACH) to 0.5 ACH. The trend accelerated into this millennium. Homes built since 2000 may have an AHC of 0.1-0.2.
Decreased ventilation increased the concentration of indoor pollutants and gave rise to a host of medical problems including sick building syndrome. The sustainable design movement and green building rating systems originated in large part as a response to health issues defined by internal environments.
Green rating systems assess energy efficiency and environmental footprint as well as ventilation, filtration, material emissions, indoor pollutants, thermal and lighting conditions, and availability of daylight views. Green buildings consistently demonstrate lower concentrations of particles, nitrogen dioxide, volatile organic compounds (VOCs) and allergens compared to conventional structures.
The benefits of green buildings are not subtle. Studies have consistently documented better sleep quality, fewer health complaints, higher cognitive function and improved productivity in green homes, schools and office environments. One weakness of studies documenting the superiority of green buildings has been their reliance upon subjective reports.
To address this limitation, a recent study blinded both researchers and subjects to environmental conditions. Investigators from Harvard, SUNY and Syracuse University simulated three environments at the Willis H. Carrier Total Indoor Environmental Quality Laboratory: low-VOC (Green), high-VOC (Conventional) and a higher ventilation low-VOC (Green+). They designed the experiment to quantify the impact of indoor environment on cognitive function.
Twenty-four professionals were recruited after being screened for smoking and asthma. They served as their own controls. The different environmental simulations were designed to assess commonly experienced conditions. Three test parameters were controlled: ventilation, CO2 and VOCs. Two ventilation rates were selected, 20 cfm/person (the minimum required ventilation rate for both green and conventional buildings) and 40 cfm/person. Cognitive function was measured with a validated instrument (Strategic Management Simulation, SMS) designed to test higher-order decision-making.
The results were astonishing. On average, cognitive scores were 61% higher when working in Green spaces and 101% higher in Green+ spaces compared to Conventional ones.
Specific subsections of the cognitive test warrant mention. In the Information Usage section (testing capacity to use both provided information and information that has been gathered toward attaining overall goals), Green and Green+ conditions yielded scores 172% and 299% higher than under the Conventional condition. Similarly, in the Strategy section (ability to plan, prioritize and sequence actions) Green and Green+ conditions produced scores that were 183% and 288% higher than Conventional conditions.
In other words, exposure to CO2 and VOCs at levels found in typical offices dramatically compromise the ability to think clearly.
In the next installment of “Building Health” I will speak about indoor environmental guidelines and how you can test and treat your home or office.
In the mean time, I would recommend exploring the quality of your indoor environment at home and work. For most of us it is a blind spot in our vision of healthy living. 90% of our time is spent indoors.
What you breath is as important as what you eat.