We can't work this way every day.
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Since moving to its new office a year ago, Windsor Federal Savings, a Connecticut-based bank, hasn’t had a single instance of Covid transmission through the workplace, even with staff back on both hybrid and full-time schedules in the administrative offices and branch locations.

Because it was in the process of designing its current office space as the pandemic hit, Windsor Federal was able to build its office with the pandemic in mind. In addition to following local mask mandates, the company added handwashing stations at the entrance and ensured physical distancing between workstations. But one of the most important upgrades was improving ventilation and air filtration by upgrading the HVAC system and placing HEPA filters at each workstation.

Windsor Federal president and CEO George Hermann initially announced the changes to the office in his weekly emails to the entire staff. He says these upgrades were essential to not only making the office safer but also to make employees feel more confident while in the office. “I don’t know if people are ever going to feel as comfortable working in traditional offices,” he says, “so creating office spaces that are safe is going to be very important to workers moving forward.”

Ventilation and air cleaning measures like those adopted by Windsor were found to reduce the concentration of Covid aerosol particles by 80-90%, according to one study, making them one of the most important ways for workplace leaders to protect their employees, alongside rules around masks, testing, and vaccines.

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These measures have become increasingly important to employees across the country. Some 82% of office workers report being concerned about indoor air quality, according to a recent study by Honeywell, and 62% of respondents would quit if their employer did not take necessary measures to create a healthier indoor environment that promotes well-being, according to a study conducted this winter.

One way to assess the quality of ventilation is through carbon dioxide (CO2) concentration, which can be measured easily and inexpensively using infrared CO2 meters that cost as little as $100. The CDC recommends a target benchmark of 800 parts per million (ppm) or below. Any room that doesn’t meet that threshold has poor ventilation, increasing the likelihood that Covid particles linger in the air, and requires further investments in filtration and air cleaning.

There are a few surefire ways to improve indoor air quality in your office—upgrading the HVAC system, increasing natural ventilation, and installing air filtration and air cleaning. The appropriate measures depend on building infrastructure, the size of the staff, and the office layout of the office—but the following tips can help assess what needs to be done.

Get the most out of your HVAC system

For those working in buildings with modern HVAC systems, you’re in luck. A few simple and inexpensive adjustments to the HVAC system can get offices to that 800 ppm number, eliminating the need for additional HEPA filters.

Start by opening outdoor air dampers wider, which allows more outdoor air to flow into the system, and upgrading HVAC filters to the highest MERV (minimum efficiency reporting values) rating the system can handle, ideally MERV-13 or higher. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) also recommends disabling demand-controlled ventilation, which adjusts the ventilation rate based on occupancy. The feature is designed to save energy when there are fewer people in the office, but ventilation rates should be maintained whenever people are present as long as Covid continues to spread.

For office buildings, the CDC recommends also flushing out building air when it is not occupied by running the HVAC system full blast for two hours before people arrive and after they leave. Doing so allows office air to be completely replaced, taking any exhaled Covid aerosols out of the workspace. Running the air conditioning in an empty building may seem counterintuitive, but it can also clear out Covid aerosols left by anyone who might have been inside during off hours—a security guard, janitorial staff, or just a junior associate having a late night at the office.

No HVAC system? Boost air quality with natural ventilation

If you’re in an older building without a modern HVAC system, what works at the local coffee shop works at an office: Ventilating the workplace can be as simple as keeping doors and windows open and, when possible, placing an outward-facing fan to aid air circulation.

These simple measures can make a significant difference for indoor air quality, but they’re less predictable than a centrally controlled HVAC. Keeping doors and windows open to improve indoor air quality becomes more complicated when the air quality outdoors is poor due to smog, wildfire smoke, or excess humidity. And it can be difficult to measure whether airflow is maintained throughout the building.

For these reasons, Faye McNeill, professor of Chemical Engineering and Earth and Environmental Sciences at Columbia University, recommends that those with the budgets to do so supplement natural ventilation with HEPA (high efficiency particulate air) filters, which can be placed around an office.

“My rule of thumb is: When in doubt, install HEPA filtration,” she says, “That is what you would do anyway if you discovered that the ventilation was inadequate in a space, so if there’s no easy way or for you to get ventilation data or if the cost of actually doing the measurement were to be higher than just buying a HEPA filter, just get the HEPA filter.”

Upgrade filtration to clean recirculated air

Portable air cleaners are one way to filter out virus particles in the air. HEPA filtration units can be placed anywhere around the office, based on air flow, risk level, or occupancy. There are dozens of models on the market, varying in both price and clean air delivery rate (CADR). To choose a model for your office, use the EPA guidelines to identify the appropriate CADR for the size of the room. In larger rooms, multiple HEPA units can be used to cover the whole area.

For a low-cost version, the Corsi-Rosenthal is a DIY contraption that comprises a box fan, 5 MERV-13 air filters, and duct tape. It achieves CADR comparable to HEPA units several times the cost. Indoor air quality Twitter (yes, that’s a thing) has blown up the #corsirosenthalbox, with variations on size and even a wearable version.

Approach air quality with transparency, accountability, and flexibility

For workers to feel confident working in the office, workplace leaders should communicate clearly about their plan to improve ventilation—how do they plan to maintain indoor air quality and how will they measure success? Facilities managers should place CO2 meters around the office to monitor ventilation across the office and throughout the day, and encourage employees to speak up if ventilation is inadequate.

Leaders should also act quickly and with flexibility in response to changing conditions. If ventilation is inadequate, there should be a plan to supply HEPA filters or other air cleaning. It’s important to remember, too, that improving indoor air quality is no silver bullet. Ventilation and filtration mostly targets Covid spread through far-field aerosol transmission. For close contact transmission, infection that occurs between people within six feet of each other, other Covid mitigation measures are still important, like limiting time indoors, social distancing, and wearing masks. As the pandemic continues to evolve, each of these prevention measures will continue to be important, especially during major outbreaks.

Invest in air quality for the long-run

Improving indoor air quality is essential to get through this phase of the pandemic, but poor ventilation has long been an issue in American workplaces long before we had ever heard of Covid. Low indoor air quality has been associated with lower productivity and cognitive function, increased disease transmission, and the prevalence of sick building syndrome (SBS), an acute or chronic health condition with symptoms linked to building air quality.

As early as 1991, the EPA warned that poor ventilation could contribute to the buildup of chemical and biological contaminants, causing the cold-like symptoms of SBS. A 2001 report from the Los Angeles Times spotlights Diana Scott, an attorney in Los Angeles, who spent 11 years plagued with SBS symptoms in a dusty, poorly ventilated building. Her solution? Bringing an air filter to work.

Ultimately, Scott’s symptoms didn’t entirely subside until she moved to a different office—one with better indoor air quality. Over 30 years later, the sickness and symptoms may be different, but what we knew then is still true now: By investing in ventilation and filtration improvements now, workplaces can protect employee health and wellbeing long into the future.

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