It’s Time for Companies to Monitor Workplace Air Quality


This article was written by: Joseph G. Allen

Original Article —

When the Canadian wildfire smoke hit New York City in June, I got a call from a senior executive with a pressing question: was the air inside their company’s building safe for employees to breathe? I could confidently answer yes thanks to the indoor air quality sensor system I’d helped them deploy several months before. According to the real-time data, particle levels were below the health-based limits even as outdoor levels surged to more than 400 ug/m3 — levels that we know is associated with not only headaches and eye irritation but also heart attacks and hospitalizations.

A similar thing happened just the other week when a fellow professor at the Harvard School of Public Health pinged me with concerns about air flow and Covid-19 risk in their classroom. Because we’d installed similar air quality sensors, I was able to quickly see and share that the space exceeded the ventilation targets we had set for Covid. We’ve now rolled out similar sensor networks at Harvard Business School and in the Harvard University Health Clinics.

The movement toward real-time air quality monitoring is growing. Both Denver’s and Boston’s public school systems have put these types of sensors in classrooms and make the data publicly available, so parents and caregivers can, for the first time ever, evaluate the air their kids are breathing. New York City is considering a similar plan for schools and government buildings. Amazon just rolled out a real-time air quality monitoring network across its entire global commercial office portfolio (Disclosure: I advised on this project, too, and my company performs ongoing analytics.)

Organizations that aren’t yet thinking about how to implement real-time “health” monitoring in their buildings should do so soon for a variety of reasons. First, because the proliferation of lower-cost sensors represents both a paradigm and a power shift. The days of a company hiring someone like me, a certified industrial hygienist, to test a building with a $5,000 scientific instrument over the course of a day and then write up a report are waning. Now any employee or customer can collect rudimentary air quality data in real time with a portable, hand-held sensor that costs about $150. People are taking these sensors into their offices, favorite coffee shops, airplanes, and everywhere else and often sharing the results on social media, sometimes publicly shaming owners of venues where the readings are bad. This is a transformational change.

Beyond not getting caught off guard, companies that deploy their own air sensor networks will find that they offer timely actionable information in moments of crisis (as in the wildfire and Covid-19 uptick examples). They can also help identify areas of the building where air quality isn’t dangerous but is still below the level at which research confirms there are productivity benefits. And sensors are a way to ensure buildings can be both energy-efficient and protective of employee health.

Outlining the benefits

Worker health, safety, and presence. Better air in buildings is associated with less sickness and fewer missed workdays. We know that viruses like SARS-CoV-2, influenza, and RSV are transmitted through the air, and “superspreading” events tend to occur indoors where there is poor ventilation and filtration. Some workers cite this as a reason for not wanting to return to the office. But when you monitor air quality, you have objective data confirming that the building is performing the way it should to remain healthy and safe. In the past, humans were the sensor, and companies would only know there was a problem when there were complaints, or, worse, people got sick. Now you can find issues before they become big issues and take corrective action.

Worker productivity. I’ve written in HBR several times about the scientifically proven link between better indoor air quality and higher-order cognitive function across domains such as strategic decision-making, how people seek out and utilize information, and how they respond to crises in a work environment. In short, the air your employees breathe impacts how they perform, and the only way to know if you’re in the optimal range is to measure it.

Optimizing health and climate goals. Air quality sensors can also be a secret sustainability tool. Buildings account for 40% of global greenhouse gas emissions; in some cities it’s 70%. As wrote in HBR in January, you could save a lot of energy by closing the dampers and limiting how much outdoor air comes in, but that makes for stale, germ-laced indoor air. On the other hand, many buildings are over ventilating certain areas — dumping cooled air into empty conference rooms all day, for example. If you’re already monitoring energy efficiency in your buildings, you should also have sensors monitoring health to find the optimal balance.

Understanding the basics

Having (hopefully) convinced why air quality monitoring is important, let’s talk about what’s involved. The sensors are small devices that hang on a wall, much like a thermostat, and measure a handful of key indicators of overall air quality in the space. The data feed into the cloud and can be accessed on a dashboard or integrated into existing building management systems. Nearly all the air quality systems on the market, including lower cost ones, measure the same handful of indicators, including:

CO2: carbon dioxide is a great proxy for outdoor air ventilation. Humans are the main source of CO2 indoors, so if CO2 is high, it’s a sign that there’s not enough outdoor air coming into the building. The bare-minimum ventilation standard (which doesn’t protect against infectious disease transmission or capture the cognitive function benefits of better air) for an office equates to about 1000 ppm. Experts, including the Centers for Disease Control, recommend setting the CO2 target at 800ppm.

PM2.5: One of the main components in outdoor air pollution is is PM2.5, which stands for “particulate matter 2.5 microns and smaller” — that is, airborne dust so tiny it can travel to the deepest part of your lungs. It’s associated with bad health outcomes, including heart and asthma attacks, poor mental health, higher likelihood of anxiety and depression, and the risk of hospitalization even after short-term acute exposures, such as during a wildfire. PM2.5 levels should be low indoors, which can be achieved through filtration, using the same MERV13 filters that were recommended to help with Covid.

TVOCS: The acronym stands for “total volatile organic compounds,” and it’s an indicator of chemical load in a space’s air. This is hard to gauge because there are hundreds and hundreds of VOCS in buildings — from carpets, paints, deodorants, and cleaning supplies — and, while some are relatively benign, others can cause cancer. The TVOC measure integrates all of them and provides one number, and there aren’t any formal health-based benchmarks. That said, there are some rough guidelines I use, mostly from my time doing forensic investigations in buildings. For example, I’m only concerned when a TVOC meter reading consistently lands over 1,000ppb. (Note that if you use even something like hand sanitizer near one of these sensors you can easily get a short-term spike of 3,000ppb or more.) LEED, the green-building certification system, gives credits for keeping TVOCs under 500ppb but would like to see less than 300 ppb, and you really shouldn’t see sustained levels higher than this in an office building. If TVOCs are higher, take a look around to see why. It could be ”nothing” like someone having just cleaned a desk nearby, or something potentially more dangerous like vehicle exhaust is entering your building from the loading dock, parking garage, or nearby traffic.

Temperature and relative humidity (T/RH): Thermal comfort is a combination of several factors, including temperature and relative humidity, as well as physical activity, attire, air movement, and personal factors. Many buildings only measure temperature, but that’s insufficient. First, most people can appreciate that a 90F day with low humidity is very different than a 90F data with 90% humidity since the latter has a “real feel” of 110F. Second, RH is really important to health. Too low and your body’s main defenses in the lungs aren’t as effective at capturing and clearing airborne pollution. Too high and you create conditions for mold growth indoors. In buildings, you want to aim for a sweet spot of about 70–76F and 30–60RH.

Making implementation decisions

In my two decades using real-time instruments for forensic investigations, building my own with my Harvard team, and trying just about every sensor made, I’ve learned a few lessons. Simply buying off-the-shelf sensors and sticking them on the wall without much thought is a recipe for human — and corporate — risk. Here’s what you need to consider and be thoughtful about to get it right.

Sensor placement and density.

For the sensors to reflect what people in the building are experiencing, you need to place them in occupied areas at “breathing height” — on a wall generally four to six feet off the ground.

The trickier question — and a place many are winging it — is how many sensors you need. I’ve seen recommendations from one sensor per 50,000 square feet to one per 500 square feet. Modeling I’ve done with colleagues, designed to account for how gases and particles flow in time and space, found that about one sensor per 2,000–3,000 sq ft is about right.

Setting thresholds.

The next step is to set thresholds for action. Many systems on the market use a too-simple approach where any little blip that exceeds a standard threshold sets off alarm bells. Hundreds of “alerts” per day aren’t helpful. Instead you want to focus on what metric has been exceeded, for how long, and where.

Amazon is using an algorithm my company developed called HEAAL, which stands for Health-Optimized, Excellent, Action, Alert, Limit. When a measure of air quality is at “Action” level it’s not immediately dangerous and should be looked at by facilities within the month. At “Alert” level, the situation should be evaluated within two weeks. “Limit” means you are potentially endangering worker health, so the issue should be escalated to an environmental health and safety team and acted on within a day or two.

Remember also to staff appropriately. When the data start streaming in, you’ll want someone who is trained to actively analyze it. Any company measuring air quality is obligated to review and respond to red flags.

Developing the response plan.

After you’ve set your thresholds, and your triaging system, what happens when the system flags a problem? First, ask yourself if there are any “data flags.” Your system or team should be watching for things like unreasonable data (Are the measurements even plausible? For example, 300 ppm of CO2 isn’t.), flatlined data (is the sensor “stuck” reporting one value?), agreement across sensors (are nearby sensors reporting wildly different values?), and calibration (are the data ‘drifting’ over time?).

Once you feel okay about the data quality, determine the scope of the issue: Is it one sensor? Multiple sensors on same floor, indicating a floor-level problem? Entire building? Multiple properties in an area, indicating a wider issue like the beginning of a rise in outdoor air pollution?

Two things aren’t going away: Covid has led to a now universal awareness about the importance of indoor air quality, and these new low-cost, small air quality sensors are proliferating quickly. A head-in-the-sand approach to these issues won’t hold for much longer. Organizations must instead be proactive: deploying sensors and systems, getting a feel for the data, and developing a response plan to keep the people in their buildings safe, maximize worker productivity, and support climate and sustainability goals. Is your business ready?



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