While Rising Carbon Dioxide Levels in the Atmosphere Cause Great Concern Worldwide, Most of Us Pay Little Attention to Risks Posed by CO2 Changes Indoors
Miniature Sensors Can Detect Potential Dangers of CO2, Berkeley Research
While rising carbon dioxide levels in the atmosphere cause great concern worldwide, most of us pay little attention to risks posed by CO2 changes indoors.
CO2 concentration in fresh air is about 400 parts per million (ppm). But get a group of people packed in a closed indoor space, and CO2 concentration can rise quickly. Recent studies suggest that as levels increase above 1,000 ppm, decision-making and other cognitive abilities decline.
Roya Maboudian, Professor of Chemical and Biomolecular Engineering, Bakar Fellow, studies the properties of nano-materials, including how their surfaces affect their performance. As a 2019-2020 Bakar Fellow, she is developing small, inexpensive and sensitive CO2 sensors. She described her research and its potential.
Q. Before people start having cognitive problems from high indoor CO2 levels, how else are they affected?
A. When concentrations in a room are too high, people become drowsy and their attention starts to lag. High CO2 levels are suspected to play a role in “sick building syndrome,” which includes symptoms like shortness of breath, dizziness, headaches and more.
Q. What causes the CO2 levels to increase in-doors?
A. We naturally produce CO2 as we breathe. Exhaled breath contains about 40,000 ppm of CO2 (1000 times higher than in outside air). So, without adequate ventilation, the CO2 concentration increases indoors.
Q. How are CO2 levels detected now?
A. The most commonly used device is called a nondispersive infrared sensor, or NDIR. They’re accurate, but they are difficult to miniaturize, they require electrical power to operate, and they’re expensive – hundreds to thousands of dollars.
Q. How do the sensors you are developing address that problem?
A. They are small and don’t require electrical power. Each person could wear an individual sensor in the form of a small badge. They would be very useful in areas where many people congregate or work together, like in an office or a classroom.
Q. How do the new sensors work?
A. They’re easy to operate -- in fact there is nothing to operate. They indicate changing CO2 levels by changing color, like pH strips we are familiar with. If the color indicates a high level of CO2 the person would know that they need to open a window, go outside or adjust the building HVAC.
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