For the past several weeks two groups, the Ventilation Working Group and the Indoor Air Quality Working Group have delved into air quality issues related to COVID-19 and to the impact of wildfire smoke on indoor air quality.
The charter of the Ventilation Working Group was to determine if engineering controls such as adjustments to the heating, ventilation, and air conditioning systems, germicidal UV light, and HEPA filtration are needed in response to recent scientific concerns and guidance regarding airborne transmission of SARS-CoV-2.
The charter of the Indoor Working Group was to determine what controls need to be established for indoor air quality for buildings at the Lab and offsite locations. The Lab has outlined controls for outdoor workers, but during recent smoke events there has been a need for guidance from the lab community for actions people can take when the air quality is compromised inside buildings. Controls to be established include engineering controls and administrative controls.
Five of the working group members recently sat down to discuss what they’ve learned about ventilation and air quality. Joining in the discussion were:
- Rengie Chan, who is a research scientist in the Energy Analysis and Environmental Impacts Division. Her research area is indoor air quality and building ventilation.
- Julie Drotz, Environment, Health and Safety Manager who is a Certified Industrial Hygienist and a Certified Safety Professional. She works with the Facilities Division and PIMD as their safety manager.
- Laurel Davis, Environment, Health and Safety Manager in the EHS Division Research Support Team. She is a Certified Industrial Hygienist with her Master’s in Public Health.
- Rob Connelly, Environment, Health and Safety Manager, who is a Certified Industrial Hygienist and a Certified Safety Professional. He manages the EHS Construction and Maintenance Field Support Team.
- Oren Rieger, who is a mechanical engineer for the Facilities Division. He is a Professional Engineer.
The five will be available to take your questions on Wednesday, September 23 at noon in a Brown Bag session.
Elements: Can the virus that causes COVID-19 be transmitted through ventilation systems? Why or why not?
Rengie Chan: The coronavirus that causes COVID-19 is mostly transmitted from person to person through close contact. Even though poor ventilation is a risk factor for transmission, there is no definitive evidence that the virus is transported through a ventilation system from one part of a building to another for spaces that have functioning ventilation. For this reason, the Lab is focusing on the basic precautions such as maintaining distance, wearing face coverings, and washing your hands.
Elements: Even though your literature review shows that ventilation systems are usually not a transmission path, has the Lab done anything differently with its ventilation system to mitigate any possible risk of transmission?
Laurel Davis: We haven’t made any changes to our buildings’ ventilation systems in response to COVID-19. The Ventilation Working Group evaluated the available evidence and measures that are effective at minimizing the risk of transmission. We concluded that the heating, ventilation, and air-conditioning, or HVAC systems in the Lab’s buildings provide adequate control as currently designed and maintained when combined with existing source control strategies. We determined that it wasn’t necessary to make changes such as increasing the amount of outside air or increasing the level of building filtration. Our buildings either already have high-efficiency air filters or are in the process of being upgraded, so we will continue our efforts in this direction.
Rengie: There’s a low probability that COVID-19 can be transmitted through a ventilation system. And because of that, the Ventilation Working Group felt that it was not necessary to make recommendations about making changes to the ventilation system as far as increasing outdoor air. That said, we do recognize that there may be some spaces that may not have very good ventilation, and those spaces, if they need to have multiple people working in them, will need to be evaluated for a determination of what controls can be put in place to enable more than one person to work in those spaces.
Elements: How do you balance airflow for COVID-19 with airflow for poor air quality?
Laurel: The Ventilation Working Group found that increasing the amount of outside air into our buildings would not be necessary or effective because transmission of the virus through the HVAC system is unlikely due to the existing dilution and filtration. As long as buildings are operated per building code, the amount of outside air can vary without impacting the risk of COVID-19. When we reduce the amount of outside air into a building in response to wildfire smoke concerns, we do so within the requirements of the building codes, and we do not increase risk of COVID-19.
Elements: Many of us like to use small fans to move air around in our indoor space. Is that something that you recommend?
Laurel: We recommend that the HVAC systems in our buildings be allowed to operate as they are designed to do. We recognize that when the temperature is warm people may want to use small personal or even larger area fans to get a sense of cooling. However, there is a potential for fans to spread aerosols containing virus particles if they are positioned to blow air directly from one person toward another person. Unless it is absolutely necessary, we recommend that portable fans are not used in the work area. If a fan must be used, such as in a space with no HVAC system, then it should be positioned so that it blows air in an upward direction or toward an unoccupied area of the room.
Elements: What does the working group recommend about opening or closing windows?
Laurel: The same kind of principle applies to windows. If a space has sufficient ventilation, let the HVAC system work and leave the windows closed. If the space has poor ventilation, then opening windows can help increase the ventilation in the area. However, it is important that people within the space are not positioned in a way that air would blow past one person directly toward another.
Elements: Is it OK to take your face cover off to eat lunch or have some water?
Rengie: We think it’s okay for people to take off their face covering to eat in an enclosed individual office. As an extra precaution, we are recommending a 30 minute waiting period – if the space is used sequentially by different people, so that any virus in the room air has time to be removed by ventilation or settle before the next user walks in. Don’t forget to clean the surfaces before and after you eat.
Elements: Did the working group look at the use of ultraviolet light to kill viruses?
Laurel: Yes, we did. The Ventilation Working Group took a look at many different measures that had been proposed by various agencies for minimizing the risk of COVID-19. Germicidal ultraviolet or UVGI systems are typically installed in crowded, public settings such as healthcare facilities, prisons, and shelters. UV systems must be fully designed and factors such as poor air mixing, fast airflow, and dirty UV bulbs can reduce their effectiveness. After reviewing the available information on these systems, the Ventilation Working Group determined that they would not provide an added benefit to the controls that we already have in place at the Lab. In addition, a UV system certainly would never be a substitute for wearing face coverings or maintaining physical distancing.
Elements: To sum it up, what were the key findings from the working group?
Laurel: The key findings of the Ventilation Working Group were that there were no specific measures that needed to be done in addition to the way we are already operating the ventilation systems in our buildings. We do recognize that there are spaces that may not have HVAC systems or that may have inadequate ventilation. It’s important to identify and evaluate those spaces — if they need to have multiple people working in them — in order to determine what controls may be needed to improve the ventilation effectiveness. The Facilities and EHS Divisions are putting the finishing touches on a space evaluation process.
Elements: What is the Air Quality Index?
Rob Connelly: The air quality index, AQI, is EPA’s tool for communicating about outdoor air quality. It has six color-coded categories, each corresponding to a range of index values that range from zero to 500. The higher the AQI value, the greater the level of air pollution, and the greater the health concern.
Elements: There seem to be different numbers between the AQI and the numbers on the PurpleAir website. How do those compare?
Rengie: My team and other researchers have been looking at what conversion factor to apply when using the PurpleAir map. In talking to EPA, our understanding is that the closest conversion factor to use currently during wildfire smoke is AQ and U. Another way to look at PurpleAir’s data is to use EPA’s new fire and smoke map that combines readings from regulatory monitors with PurpleAir. The PurpleAir data displayed on that map has been adjusted using an EPA in-house conversion factor.
Elements: What is the safe level of air quality?
Rob: When levels are zero to 50, the air quality is considered good. Levels between 50 and 100 are generally thought of as satisfactory. And then when levels are above 100 air quality is considered unhealthy for sensitive groups. It depends on what the person’s underlying health conditions are. There’s not really one set number as a threshold.
Elements: Is there a number at which the air quality is unhealthy for everyone?
Julie: Above 151, members of the general population may experience health effects and above 301 the air is considered hazardous. Both are based on a 24 hour timeframe.
Elements: What does it mean when the air quality sites refer to PM 2.5?
Rob: PM 2.5 stands for particulate matter suspended in the air. The “2.5” means less than 2.5 microns. PM2.5 is a key component of wildfire smoke that has been shown to cause respiratory and cardiovascular health outcomes.
Elements: Do the face coverings we wear to protect us from COVID-19 also protect us from particulate matter?
Laurel: Face coverings are worn primarily to protect those around us from aerosols that we exhale. They are not rated as to their effectiveness at protecting the person wearing it from breathing in virus-containing aerosols or particulate matter from wildfire smoke. A face covering that fits closely around the nose and face will reduce large gaps through which unfiltered materials can be inhaled. There are some cloth face coverings with a small pocket into which a PM 2.5 filter can be inserted — this might be helpful for some people.
Elements: What is the process for monitoring the air quality at the Lab?
Rob: The EHS division currently is monitoring the particulate matter levels. In the near future, the Security Operations Center will be doing this. When the AQI approaches 100, EHS will alert Facilities so they have time to start the process of closing economizers before the reading reaches the 151 level where it becomes unhealthy for all individuals.
Elements: What is an economizer and how is it used?
Oren Rieger: The economizer is a combination of dampers, or sometimes a single damper, that changes the source of air entering an air handler, either from return air that’s been recirculated through the building or outdoor air.
Our process is to close the economizers, meaning to redirect the air so it recirculates through the building similar to your car when you switch the outside air button to the recirculation button. It’s the same thing, but for a building.
Elements: Many have asked whether the Lab is going to issue N95s during high smoke days in the Bay Area for indoor and outdoor workers. Is that something the Lab is considering?
Julie: We’re not issuing N95 masks because there’s no guarantee that they are going to protect people and that there are some problems with people wearing them for too long and having difficulty breathing. We’ve talked to other UC campuses about what they’re doing and it’s the same type of thing.
Personal Protective Equipment or PPE is the last line of defense. We’re trying to focus on engineering controls and eliminating exposure by having people take frequent breaks in well-ventilated areas and eliminate smoke exposure. Putting on an N95 and continuing to expose people to the hazard isn’t the best situation for anyone.
Laurel: Another driving reason why the laboratory is not issuing N95 respirators is that the Centers for Disease Control continues to ask people to avoid purchasing N95 respirators in order to reserve them for healthcare providers. The Lab feels that is an important position to take. I think the challenge is when the PM 2.5 levels in a building are the same as outside and then there is now no clean place for people to go. And that’s a challenge we all face with this level of smoke.
Elements: How is the Lab using PurpleAir sensors to better respond to air quality issues?
Julie: A lot of what we use the indoor and outdoor sensors for is to determine how our buildings are responding to the external smoke levels. Oren has put together a proposal for upgrading filters in a lot of the buildings, and they’ve implemented that program with some of our more populated buildings. We can see if the measures we’re taking are having any effects and to see if we need to maybe try something else to refocus our efforts into something that might have a better effect.
Oren: The only thing I would add here is that when the outdoor air clears very quickly the indoor air may take a while to clear out. So there may be temporary periods of time where the indoor air is worse than outdoor, but it should eventually clear.
Assuming we’re still recirculating air, each pass through the air handler cleans the recirculated air more and more. So that takes time.
We may not be immediately releasing the economizers because the outdoor air quality is fluctuating. So we wait for a certain amount of time before the outdoor air is stable and cleaner before we release the economizers.
Elements: What have you found out about the filters in Lab buildings?
Oren: We’re in the process of upgrading filters campus-wide to a minimum of MERV 13. Filters are rated on different MERV levels, MERV 1 being the worst and MERV 20 would be the best. MERV13 is the new code requirement as of 2019 for new construction. And we’re going to attempt to upgrade all of our systems to that requirement.
Elements: Is it possible to update all the buildings at the Lab to Merv 13 filters?
Oren: A system is designed around a particular filter. The fan is selected in order to pull or push air through a certain filter efficiently. So it’s not necessarily straightforward to increase the efficiency of a filter without possibly needing a bigger fan or something similar to that. In some cases there may be issues with upgrading to that level, to a MERV 13, if it wasn’t originally designed to have one.
Elements: Are portable air filters helpful in smaller spaces?
Laurel: Portable air purifiers can be helpful in cleaning the air within your space. It’s important that the portable air cleaner is sized appropriately for the space that it is in and some spaces may need more than one. A few pre-approved air purifiers are available to purchase on eBuy through Pacific Office Solutions and there is a guidance sheet that outlines the models, suitable space size, and replacement filters. If something different is needed, requests come through EHS for review and we look at those filters to make sure that they meet our basic minimum expectations.
I have been partnering with Rengie and with Raph Vitti from Sustainable Berkeley Lab to come up with an expanded list of air purifiers that would be suitable for purchase, along with a communication that outlines what are the expectations for air purifiers. These include factors such as ENERGY STAR certified, mechanical only filtration, and high clean air delivery rates. We’re doing this not just for wildfire smoke concerns. The Lab is also looking at air purifiers as a COVID-19 control measure. An air purifier can help improve ventilation effectiveness in spaces with less than adequate ventilation that requires multiple occupancies.
Elements: What’s the one thing that you’ve taken away from the work you’ve been doing as part of these working groups?
Rob: Facilities has been doing a lot of the right things. They’re shutting down economizers and they’re looking at the MERV rating on the filters and they’re making improvements there. The Lab’s scientists in the indoor air group have made a lot of recommendations as well. Those are really insightful recommendations and EHS will have a website up in the near future where folks can go to obtain a lot more information on this topic.
Laurel: My experiences working with the Ventilation Working Group, the Building Capacity Working Group, and in consulting with the Indoor Air Working Group have been very positive. It’s really great to see EHS, Facilities, and science taking a team approach to address concerns for the laboratory community during this extremely challenging time.
Julie: I’m part of the COVID-19 Operations Working Group and these two teams were put together to look at ventilation systems for COVID-19 and at the indoor air quality in regards to wildfire smoke. It’s amazing when you think of all the great minds we have at the laboratory. I know the COVID-19 Ventilation Working Group looked at hundreds of research articles. There’s just been so much work. We try to wait for public health guidance to come out to inform our decisions, not making decisions based off of one research study or one limited scope research. It’s been really great to see these people working together to come towards finding solutions that we can use at the laboratory to improve everyone’s health and safety.
Rengie: It’s been a great learning experience for me to see the layers of considerations and thoughtfulness that EHS and Facilities has given to our grand challenge – COVID-19 plus wildfires. The discussions that we had in our working groups must also be happening outside Berkeley Lab, but it’s hard to match the vigor and attention to details as we’ve done, still we are just scratching the surface. The problem of how to provide a safe and healthy workplace during extreme events is enormous.
Oren: I’d say as far as COVID-19 goes, it’s been extremely challenging to try to build the airplane as we’re flying it. There’s been a lot of information all over the place that we’ve had to sort through. I’ve never had to design something in that way before. It’s been great to have really talented people to bounce ideas off because the world’s not been providing answers and we have to come up with something for our unique campus.