Air quality readings during my trip to Puerto Rico

Air quality on plane Air quality has a significant effect on human health. During the COVID-19 pandemic, it has become an especially critical issue. Why? Because COVID-19 spreads via aerosols that can float in the air for minutes to hours. Although there is currently no commercially available way to measure the presence of COVID-19 in air, I’ve written about how measuring carbon dioxide (CO2) concentrations can act as a useful proxy for COVID-19 infection risk. Small, inexpensive CO2 meters are now widely available.

So when I took a deep (masked) breath and decided to accept an invitation to design and lead a two-day meeting industry leadership summit in Puerto Rico, I decided to bring my CO2 meter with me. What would I learn about the air quality in the airports, planes, and ground transportation I used, as well as my hotel and the summit’s convention center? Well, I uncovered significant air quality concerns in places that may surprise you. Read on to find out what I discovered. But first, a brief explanation of what CO2 measurements mean.

How do CO2 levels correlate with the risk for COVID-19 infection?

It’s complicated! Measurements of indoor CO2 concentrations can often be good indicators of airborne infection risk. But clear conclusions on the CO2 level corresponding to a given COVID-19 infection risk are currently lacking. Multiple factors influence the risk. These include exposure duration, the mixing of air in the vicinity, the exhalation volume and rate of infected individuals, and, of course, the use of masks, virus-removing air filtration, and UVC and far-UVC radiation. This article gives some idea of the complexities involved. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has summarized current thinking on indoor CO2. ASHRAE takes the position that “indoor CO2 concentrations do not provide an overall indication of IAQ [indoor air quality], but they can be a useful tool in IAQ assessments if users understand the limitations in these applications.”

More research is required, especially because of “the ubiquity of indoor concentrations of CO2 in excess of 1,000 [parts per million] ppm.” And ASHRAE reports that “indoor concentrations of CO2 greater than 1,000 ppm have been associated with increases in self-reported, nonspecific symptoms commonly referred to as sick building syndrome symptoms.” To summarize, currently, there is insufficient research suggesting CO2 levels that indicate a significantly increased risk for COVID-19 infection. However, many authorities have tentatively proposed maximum levels of around 1,000 ppm CO2 as guidelines.

air quality
From a REHVA (The Federation of European Heating, Ventilation, and Air Conditioning) journal article on CO₂ monitoring and indoor air quality.

OK, enough of this; you probably want to know what I found. Here we go!


I flew JetBlue flights 261 and 462 between Boston (BOS) and San Juan (SJU). My outbound flight, on an Airbus A321, lasted 3 hours and 43 minutes. My return flight, on an Airbus A320, took 4 hours and 40 minutes. (Don’t ask.) On both flights, I had an aisle seat in row 15. As you can see from the photo at the top of this post, I perched my little CO2 meter on my knees when tray tables had to be up. The rest of the time, it nestled perfectly into the little tray table drink recess. Here’s an annotated graph of the CO2 readings I took on my outbound flight. Air quality plane

My key flight observations

  • Boarding the aircraft led to a large spike in CO2 levels. Levels increased sharply in the jetway as I approached the passenger door. Slowly walking down a packed aisle to my seat I saw readings around 2,000 ppm. Once in my seat, the levels dropped somewhat but were still high (1,600 ppm) when they closed the door.
  • Levels stayed high (above 1,500 ppm) while taxiing until we took off. We had been on the plane for about 50 minutes at this point.
  • I estimate that about 30% of the passengers were unmasked, as well as most of the flight attendants.
  • During the cruising portion of the flight, the CO2 level stayed at REHVA’s “upper range of reliable air quality” of 1,000 ppm. The level in the bathroom was 1,200 ppm.
  • Once we started our descent, levels rose a few hundred ppm. On landing, we were at 1,300 ppm.
  • During deplaning, levels soared again. I took the photo at the top of this post, showing a reading of 2,074 ppm, at this point.
  • As soon as they opened the passenger door, levels dropped to around 1,200 ppm.
  • On my return trip (which took close to five hours) I saw similar readings, except that:
    • The cruising flight CO2 level was significantly higher (1,200 – 1,400) ppm.
    • The boarding peak was lower (1,500 ppm).
    • The deplaning peak was an unsettling 2,400 ppm.

To summarize, these readings are troublesome. Aircraft ventilation systems reportedly filter out aerosols, assuming that the HEPA filters are regularly replaced. However, the close proximity of passengers (both flights were full) still allows people to infect others close to them, as this NY Times article illustrates. The high readings I saw indicate that in-flight ventilation was not fully operative during embarkation and deplaning on either flight. I am glad I wore a high-quality N95 mask during both.


BOS airport levels were around 600 ppm. At SJU I saw readings between 650 – 800 ppm. Both of these are acceptable. Neither airport was especially crowded, however, and I would be cautious about assuming it’s OK to go unmasked there.

Ground transportation

This was a shocker to me. In the U.S. during the pandemic, when driving with others I’m used to having the car windows open, at least a little. Puerto Rico was hot and humid, and the vehicles I was in had the A/C on and windows closed. My client had arranged a car and driver to pick me up from the airport and drive me to the convention center for a couple of technical rehearsals and then to my hotel. Just the two of us in a Chevy Suburban quickly raised the CO2 level to around 1,500 ppm for the 30 minutes we were together. Luckily we were both masked.

I saw the same readings during my trip to the airport at the end of the event.

But I saw the highest readings during my travel in a shuttle bus bringing us to the opening reception. There were, perhaps, 20 of us on board. Readings spiked to over 3,000 ppm! And some of the passengers were unmasked.

The conference center

The conference center was far from maximum capacity and I only saw readings well below 1,000 ppm. We held the summit in four meeting rooms with high ceilings. We left the meeting room doors open, and my meter typically showed readings between 500 – 600 ppm. If the venue had been packed or the doors closed it might have been a different story.

My hotel

I was concerned about the air quality in my (large) hotel room because I expected it to have no openable windows due to San Juan’s climate, and this proved to be the case. Over the three nights I was there I noticed the same pattern. On entering the room during the day, readings were about 600 ppm. As evening approached, the readings slowly climbed to about 900 ppm.

I had reason to be concerned.

The increase in CO2 as evening approached was probably due to increased occupancy of nearby rooms. Building heating, ventilation, and cooling (HVAC) systems typically recirculate interior air, mixing together air from all the rooms in the building. So as guests retire to their rooms in the evening, the overall CO2 concentration in every room increases.

That means that although I was alone in my room I was breathing exhalations from other guests. If any of those guests had COVID-19, it’s possible that their aerosols would travel into the air I was breathing. There was nothing I could do to protect myself other than wearing a mask the whole time I was there (which obviously included sleeping!)

Commercial HVAC systems

Commercial HVAC systems include filters to remove dust and dirt. Typical HVAC filters will not stop COVID-19 aerosols unless they have been upgraded to MERV 13 or better (e.g. HEPA). They also need to be regularly replaced to work correctly.

Whether these mitigation measures have been performed at a hotel is hard to know. My hotel was modern, but that doesn’t mean its HVAC system was well-designed and safe. I have stayed at hundreds of hotels over the years. Some of them, based on the odor of the rooms, had ventilation problems of some kind. Paradoxically, the single-unit heating and cooling systems common in inexpensive lodgings could be safer because air entering the room only comes from outside.

Concerns like these have made me cautious about staying in accommodations that don’t have windows that can be opened. That wasn’t possible in Puerto Rico, and my CO2 monitor gave me at least some reassurance that air quality levels weren’t too bad. However, many commercial lodging offerings don’t offer this option. The inspection and, if necessary, re-engineering of hotel HVAC systems is an important step to protect guest health. Yes, it costs money, but if the owners have done this work they should publicize it as a reason to stay.

For more information about this important topic, read my article about COVID-19 transmission and air quality in buildings.


As I write this, I’ve been isolating for four days since my return, and just performed my fourth daily rapid antigen test. All have been negative. So it looks like I’ve escaped getting COVID-19 during my first major travel since the pandemic began. I recommend travelers purchase an inexpensive CO2 meter and bring it with them.

I hope the information I’ve shared in this post is helpful in warning other travelers of potentially dangerous environments. COVID-19 is far from over. As the pandemic continues, monitor your air quality while traveling—and mask up.

Travel safe!

Venues on notice: meeting planners are demanding flexible meeting space!

flexible meeting spaceTwo-thirds of meeting planners now rank flexible meeting space as a top priority when choosing a venue, according to Destination Hotels’ fourth annual State of the Meetings Industry survey.

“Among the nearly 68 percent of respondents who said that flexible meeting spaces rated an 8, 9 or 10 in importance when choosing a meeting site, two factors are driving this need. First, the objective of in-person meetings is to deliver information and insight at a level that tech-based meetings cannot; second, today’s attendees require variety in their learning environment to remain stimulated, attentive and receptive to information and different perspectives.”
—The fourth annual State of the Meetings Industry survey (October 2015), conducted by Destination Hotels

In 2011, at a webinar I gave for the International Association of Conference Centres I recommended that venues develop and feature flexible meeting space, to prepare for the growth of Conference 2.0 formats. Four years have passed, and meeting planners are now demanding these spaces.

Venues, are you ready?

Image of Apple Campus II floor plan courtesy of Office Snapshots

Eight pieces of information needed for event design

information needed for event designWhat information is needed for event design? Every week I receive requests for advice on improving existing meetings. (Design consultations on new meetings are less frequent, which is unfortunate since it’s much easier to begin with a good design than successfully redesign meetings that attendees have already experienced.)

All event designs require certain basic information. Typically, clients start with an initial consultation where we explore desires, needs, and circumstances, winkling out the basics in the process.

Quite often, however, I’ll receive emails asking for design advice that omit significant information. Here’s an example I received last week, quoted in full:

Dear Adrian,

I am a researcher working on a side-event to [an upcoming international meeting]. I work for [a European foundation] and am looking for innovative ways to engage an audience of up to 300 people in the subject of [my foundation’s mission].

We want to get away from the lecture-style format but we do not have the ability to split the group up (for translation reasons, amongst other things).

If you could offer any advice or links I would be most grateful.


Meeting designers need answers to eight questions before design can commence. The following list includes some commentary on how Dominique’s request complies.

Who is the meeting owner?

Every meeting has an owner. There is invariably a single person who has ultimate authority over the meeting objectives, budget, format, and content. A common problem for meeting designers is that they are approached for assistance by someone other than the meeting owner (who may not even be aware that a meeting designer exists or is needed.) That’s certainly the case here. When you can’t work directly with the meeting owner, any design work performed will be wasted if the meeting owner is not convinced of its value by the intermediary with whom you’re working.

Who is the meeting designer working for?

The meeting owner? The meeting participants? One or more intermediaries? Some combination?

Who is attending?

What are the profiles of desired/expected attendees? Is the event invitation-only, or is it of interest to specific groups? For Dominique’s event, are the audience members supporters of the foundation’s mission? Skeptics who need to be convinced? What are the translation issues she mentions?

What are the desired objectives/goals/outcomes?

Many clients find it hard to define their goals and outcomes for their event. Dominique wants the audience to be “engaged”. What does this mean? Engaged about what? What is the desired outcome of this engagement?

How many people?

The only meeting designs that scale are those that omit inter-attendee interaction; i.e. broadcast-style events. If you want or need interactive or participative events, the number of attendees is essential information for creating an effective design. (2/8/15/25/60/100/200/450/1000 people? Each level will generally require a somewhat different approach.) Dominique’s “up to 300 people” includes the possibility that some other breakout will be taking place that siphons off all but 30 attendees. We need either tighter bounds on this number or several alternative designs that cover a range of attendee counts.

How much time?

Are people together for an hour? A day? Two days? A week? Most of us have an idea of how much content we can be exposed to via lecture in a given amount of time. An understanding of the time needed for people to productively peer learn, make significant connections, and become a member of a valued community is far less common. The amount of time that people are together sets limits on what is possible, and informs design decisions on the most appropriate processes to use for the meeting.

What venue?

Venues often constrain what’s possible at an event. Desired objectives like engagement may be difficult or impossible if attendees are stuck in fixed-seating in an auditorium. Working in small groups can be thwarted if the venue is noisy, or undersized, or adequate breakout space is unavailable.

What resources are available to support work on the event design?

Is the meeting owner willing to work on the event design, or pass full responsibility and authority to a trusted alternative? Can you afford a day of my time to assist with your design? Are you looking for free advice? (Dominique was.)

We need answers to all these questions—and often others—before workable and effective meeting design is even conceivable. (I thought about adding the event budget to the above list, but, though it’s obviously ultimately important, it’s less relevant in my experience than you might think.) I don’t expect clients to spontaneously volunteer all this information before we first talk or meet. But it certainly doesn’t hurt if they do (and I get some reassurance that the client has made an effort to really think through what they want and the steps they might take to get it.)

Eight pieces of information needed for event design

So, I’ve shared eight pieces of information needed for event design before a meeting designer can commence their work. I’ve probably missed some other pieces of information that are important. What would you add to this list?