Last modified on June 24, 2019 by Brad Phillips

Public Speaking, Carbon Dioxide, and Nap Time

A new study suggests that public speakers, conference planners, and conference goers may have to give thought to carbon dioxide levels for an unexpected reason. 

Audience nodding off

Your audience may be struggling with a host of distractions.

One might be running through a mental to-do list, while another fields constant (though silenced) text alerts from a teen daughter who has lost her homework assignment. In our public speaking training, we work with clients to craft an audience-focused message and to attract and keep an audience’s attention. But what if your audience is still nodding off?

It doesn’t take all that many people, in a poorly ventilated room, to lead to droopy lids, lethargic responses, and lack of attention. If your audience is getting drowsy, you might have too much carbon dioxide in the room.

Audience nodding off?

As your audience exhales, the carbon dioxide levels rise. You might say the room is getting stuffier, or the air is getting a bit stale. If you were a scientist with a carbon dioxide monitor, you could be a bit more precise in your assessment. That’s exactly what Adam Ginsberg of the National Radio Astronomy Observatory did during a recent session at a conference in Helsinki, as recently reported by The Washington Post.

As he tracked the air quality in a crowded, poorly ventilated meeting room, he watched as it went from about 800 parts per million – a typical concentration – to about 1,700 parts per million. It reached that peak about an hour and 15 minutes after the talk began. Not soon after that, attendees got out of their seats and broke for a coffee break. Meanwhile, organizers opened the windows.

Within minutes, the carbon dioxide levels dropped below 600 ppm, according to the article. When the attendees returned, the windows remained open. Carbon dioxide levels stayed within the 1,000 to 1,200 ppm range. This is not the first time he’s tracked high carbon dioxide levels and reported them. He often takes his portable monitor to check the carbon dioxide levels in crowded meeting rooms during academic conferences, to highlight the importance of ventilation.

Research has found this spike in carbon dioxide not only can cause your audience to nod off, but can affect their cognitive abilities, particularly decision-making skills. Woe the speaker in a carbon dioxide-rich room who is asking an audience to assess the merits of a call to action.

Cut the Carbon Dioxide

Not every speaker will have the benefit of speaking in a well-ventilated room. However, every speaker can work to keep their audience from nodding off, despite the stale air. Bringing along a carbon dioxide monitor might be the most comprehensive way to approach all this. However, it would probably be just a bit distracting to constantly check it as you move through your presentation.

Instead, here are six suggestions that should help to clear the air:

Take breaks – Adam Ginsberg’s experiment indicates that the levels in the room he was recording reached about 1,000 in 45 minutes. Several sources indicate it’s best to keep the level below 1,000. So, if you think you might go for more than 45 minutes, plan a break or two.

Business people standing outside a builidng in a blur

Hydrate and stretch – Get the audience out of their chairs and into a new locale for light refreshments. Provide enough time for bathroom breaks, too. These can range anywhere from 5 to 20 minutes, based on the total duration of your talk.

Lunch/dinner break – If your talk is several hours, arrange for a lunch or dinner break outdoors, or in a more ventilated space.

Ventilate – During the breaks, crack open windows and open doors. If the room and organizers allow, and if nearby distractions are minimal, keep doors and windows open throughout your talk. The carbon dioxide being exhaled by your audience will have a chance to dissipate. The air will stay “fresher” longer.

Get moving – Do something interactive, such as getting your audience up for a demonstration or a volunteer activity. You also could ask for a show of hands. Even if such a strategy doesn’t reduce the carbon dioxide levels, physical activity gets the heart rate up and the blood pumping. This leads to a release of endorphins and an increase in energy levels.

Go green – If the conference space is under your purview, consider adding live plants, which will absorb some of the carbon dioxide and thereby lower the levels. 

Employing a few of these suggestions will be not only be enjoyable for your audience – al fresco dining is a rare treat at corporate conferences – but make your presentation a literal breath of fresh air.