#38 - Simon Jones: Thoughts on the ASHRAE position document on air cleaners and filtration, a new paper on ventilation in UK schools and more.

The week on the podcast.

I reviewed ASHRAE's position document on air cleaners and filtration. Should we be reading between the lines, and is it one of those documents that will just reinforce whatever your world view is on the subject.

We take a closer look at school environments with insights from a SAMHE paper examining ventilation in 322 UK schools. Learn how CO2 levels fluctuate with the seasons and how poorer ventilation disproportionately impacts schools in disadvantaged areas.

And I catch up on a social media post in the week about measuring ventilation in homes.

Daycare Story

ASHRAE Position Document

SAMHE Paper on Ventilation in Schools

Chapters

• 0:00 Air Quality and ASHRAE Position Paper
• 12:43 Improving School Ventilation for Health

Transcript

Simon: 0:00

Air quality matters inside our buildings and out, and we already have many of the tools we need to make a difference. The conversations we have and how we share this knowledge is the key to our success. I'm Simon Jones and this is episode 38 of the Air Quality Matters podcast Coming up. We discuss ASHRAE's position on air cleaners, a first reaction to a paper that's just dropped from our friends at Sammy and Henry Burridge a previous guest on this podcast on ventilation rates in schools, and to pick up a conversation I was having this week on measuring ventilation rates at scale. Thanks for listening. As always, do check out the sponsors in the show notes and at airqualitymattersnet. This is the Air Quality Matters podcast.

Simon: 1:09

I was just reading another article this morning shared by Pavel Walgotsky on air cleaners. The study conducted at two daycare centres in Helsinki found that using air purifiers reduced sick days amongst children and staff by around 30%. This research, led by the E3 pandemic response, observed this effect during cold and flu season, suggesting that cleaner air could significantly reduce the incidence of respiratory illnesses. The study aims to develop an air purification strategy suitable for daycares, with final results expected in the spring, and could have significant implications for reducing illness-related absences and associated costs. It's really interesting for me to see more and more of these studies appear and I'm guessing this is a trend that's going to continue post the pandemic as the information from places where these products have been deployed or worked through and papers are produced. It will also be interesting to see over time how the focus shifts, perhaps from infection control to more general air quality, particularly from my perspective.

Simon: 2:27

Ashrae, the American Society of Heating, refrigeration and Air Conditioning Engineers, who effectively set many of the standards in North America, or at least set the position of an enormously influential market, recently released a position paper on air cleaners. They explain in this document that airborne contaminants can come from both indoor and outdoor sources, and filtration and air cleaning technologies can help improve indoor air quality by removing or neutralizing at least these contaminants, though their effectiveness depends on various factors like type of technology and how it's applied. They point to the fact that research shows that some air cleaning methods are effective, but there's limited evidence on their direct health benefits and potential long-term impacts. And while these technologies can reduce energy use and enhance ventilation, they may also have unintended side effects, such as emitting by-products or affecting how people perceive air quality rather than its actual air quality. Ashrae, in this position paper, emphasises the importance of understanding both the advantages and limitations of these technologies, encouraging the HEVAC industry and the public to carefully consider their use. The goal is to balance improving air quality with potential challenges like energy efficiency and operational risks. Look, it's complex, and that's no surprise. To quote directly from the position document, the effectiveness of various filtration and air cleaning technologies, both in duct and in room, depends on the nature of airborne contaminants, the airflow rates and patterns in the space induced by the HVAC layout and air cleaners, the operation principles of the filtration and air cleaning technologies and their proper applications. So why is ASHRAE taking a position on filtration and air cleaning? Well, as ASHRARAE states, it's committed to addressing the impact of HVAC related technologies on human exposure to airborne contaminants. As part of its core mission, ashrae actively sets standards and guidelines to evaluate the effectiveness of HVAC technologies, including filtration, air cleaning, disinfection, to reduce the exposure to contaminants and safeguard the health and comfort of building occupants. This evaluation is crucial in guiding ASHRAE members and the public to select and use filtration and air cleaning technologies. Additionally, the evaluation is necessary as the technologies are included in standards prepared by ASHRAE, as I've mentioned. So the position paper has two main parts to it really. Number one, that ASHRAE takes a position that piece to it. And two, that they recommend something piece to it.

Simon: 5:42

I'm not going to read the position paper verbatim. I'll include it in the show notes, as you'd expect, but I do have some thoughts I'd like to share with you. For me, reading the document, you can literally see the hours that have been poured over this document to get it technically correct, have the right tone and tread a certain line. Knowing some of the authors, as I do, they would have taken this very seriously. Overall, I think it's a solid position document. But there is a but and I completely understand why. But I couldn't help coming away from this feeling that this position document had to tread a kind of a line and, depending on your perspective or world view on this technology, you could come away from this with very different takeaways. I'll try and explain why. So let me put my cynical hat on.

Simon: 6:40

To make some points, the document talks about the need for more research. The document's call for additional research to quantify the benefits of filtration and air cleaning suggests that the current evidence base may not be as solid as it should be. This could indicate that the recognition that the purported benefits of these systems may not be fully understood or may have been overstated based on existing studies. It talks about predicting by-products and long-term risks. The recommendation for research on by-products generated over the service life of these devices highlights potential risks that have yet to be thoroughly investigated. This suggests that you could make the argument that the industry may have overlooked important health considerations in its rush to market these technologies.

Simon: 7:40

The document talks about application-relevant testing. The documents push for laboratory testing under conditions that more closely simulate real-world application reflects the recognition that current testing methods may not be fully predictive of actual performance. This gap between lab and field performance could mean that many technologies currently in use are not as effective or even as safe as their lab results might suggest. It also talks about whole service life assessment. The emphasis on assessing devices over their entire service life rather than just under initial conditions indicates that there may be significant degradation in performance or even safety, perhaps over time, which is not being fully adequately captured in current evaluations. This could lead to users being unaware of a decline in efficacy of their air cleaning systems perhaps. It also talks about expanding standards and guidelines, the call for more comprehensive standards and guidelines suggests that the current regulatory framework may be insufficient, particularly for newer technologies. This implies that many products on the market may not be held to rigorous standards, potentially leading to inconsistent performance and perhaps, again, even safety. The suggestion to develop a standard protocol for estimating health risk reductions based on laboratory performance hints that existing claims about health benefits may be speculative or not backed by robust evidence. This raises questions about the true health impact of these technologies and whether they deliver on their promises.

Simon: 9:39

And finally, evaluation with ventilation. The recommendation to compare the effectiveness of filtration and air cleaning with traditional ventilation methods, as well as their energy and carbon impacts, suggests that the advantages of these advanced technologies may not be as clear-cut as often portrayed. The call for research on the integration of air cleaning technologies with HEVAC systems and their impact on energy consumption reflects concerns that these systems may not be as efficient or perhaps environmentally sustainable as claimed. This could lead to higher operational costs and environmental impacts that users might not expect. Now, I've been a bit cynical here. I get that, and you could do that with almost any position document, I guess. And it's clear from the emerging evidence that air cleaners can have a positive impact on buildings in the right circumstances. But I'd be interested to hear what you think here. When you read this document, what's your takeaways from it, and look compared to where we were, even a couple of years ago during the pandemic, when the anything was better than nothing approach was king, I think it's actually pretty amazing to see how quickly the sector is getting organized here.

Simon: 11:07

I'll have you back to the podcast in a minute. I just wanted to briefly talk to you about 21 Degrees, a partner of this podcast. Formerly the Green Building Store. They were founded in 1995 by three exceptional building professionals. The company grew out of their frustration with the poor availability of ecological building products. I've known them for years as the go-to company in the UK for end-to-end design-led MVHR systems, for end-to-end design-led MVHR systems. We spend the majority of our time in our homes, so they should be the best. They can be, comfortable and healthy to live in, with exceptional efficiency, in fact, life-changing homes. At 21 degrees you won't find a more trustworthy, straight-talking, passionate about what they do and approachable group of people. I speak a lot about the performance gap on this podcast and what we can achieve if we value ventilation highly enough. 21 degrees embodies that sentiment for me embodies that sentiment for me. So if you're building a home, looking to install ventilation or need to talk to experts in the field, I can't recommend them highly enough. Links are in the show notes at airqualitymattersnet and you can google. We Are 21 Degrees.

Simon: 12:43

Now back to the podcast, so onto a newly released paper. Hot off the press and in my inbox this morning is a new paper from our friends at SAMI, authored by Samuel Wood, alice Handy, catherine Roberts and Henry Burridge, who we've had on this podcast. The study looked at how well classrooms in 322 UK schools were ventilated by measuring levels of carbon dioxide during the autumn term of 2023. So very recently and I think what's interesting about that timing is we're now far enough away from the pandemic that we're getting at least back close to where we were pre-pandemic in our use of those spaces. On average, the ventilation was found to be better in warmer weather and worse in colder weather, which might be counterintuitive because we've always understood that ventilation, particularly natural ventilation, works better in winter, when you've got a bigger difference in temperatures between inside and outside. Most of the schools managed to keep CO2 levels below the recommended limits set by BB101, but some classrooms had very high levels of CO2, indicating poor ventilation that needed to be improved. The study also found that schools in poorer areas, state-funded schools and secondary schools tended to have higher CO2 levels, suggesting they had worse ventilation outcomes. These findings remained consistent even when they adjusted the analysis to account for differences in CO2 production by older children in secondary schools. Overall, I think the study highlights the need for better ventilation in schools, especially in colder weather and in schools serving more deprived areas deprived areas and reinforces the point, really, that exposure to poor air quality and ventilation is not distributed equally in society.

Simon: 14:47

So what was done? Well, there was data collection. Co2 levels were monitored in classrooms across 322 schools, providing around 10,000 school days worth of data. Schools providing around 10,000 school days worth of data. The researchers controlled for outdoor temperature as a variable and used statistical methods to analyze how different factors like funding type, geographical location and student age groups influence ventilation. What were the main findings?

Simon: 15:19

Well, the interesting ones that pop out to me certainly were that the average ventilation rates across all schools was approximately 5.3 litres per second per person, was higher in warmer weather, as we mentioned earlier, at 6.8 liters a second per person, and lower in colder weather, at 3.8 liters a second per person. Bearing in mind, these were the averages, so there will be some outliers here. Most schools kept their daily mean co2 levels below the uk government's recommended threshold of 1500 parts per million. However, a minority of classrooms experienced very high levels of CO2, indicating poor ventilation. The likelihood of exceeding the 1500 parts per million threshold increased by about 20% when outdoor temperatures dropped to around 5 degrees, which I think is really interesting. Schools in more deprived areas, state-funded schools and secondary schools generally had higher CO2 levels, indicating poorer ventilation. When accounting for the greater CO2 production associated with older children, it was found that ventilation rates did not differ significantly between primary and secondary schools. Between primary and secondary schools, the study suggests that, while most schools maintain adequate ventilation, there are specific classrooms, particularly in colder weather and more deprived areas, that suffer from poor ventilation. The findings emphasise the importance of improving ventilation in these areas to ensure a healthier learning environment for students.

Simon: 17:11

There are some weaknesses to this study, as you'd expect, and the study relied on air quality monitors placed in classrooms, but the precise placement of these monitors within each classroom was not controlled or verified by the researchers. This means that there could be variability in how and where this data was collected. That might affect the accuracy of the results, but that's not uncommon. The study acknowledges that without detailed contextual information about the exact monitor locations, some uncertainties exist around interpreting the CO2 data. The schools were responsible for setting up the monitors according to guidelines provided by the researchers. However, the study notes that this setup was not directly supervised, leading to potential inconsistencies in how monitors were deployed across different spaces and different schools. The study involved 320 schools, but only about 190 of these schools met the criteria for inclusion. In the final analysis, this means that the study findings may not fully represent the ventilation conditions across all UK schools. Although the study attempted to include a diverse range of schools, certain regions or demographic groups may have been underrepresented. For example, the study mentioned that none of the data from Northern Ireland was included due to insufficient data, which could limit the generalizability of the findings to the entire UK.

Simon: 18:47

The estimation of the per person ventilation rates was based on CO2 measurements and several assumptions about occupancy and CO2 production rates. While these methods have been validated, the study acknowledges that they come with inherent uncertainties, particularly when there is limited contextual data about classrooms, occupancy and usage patterns. The study primarily focused on UK schools, which are typically naturally ventilated. These findings may not be directly applicable to schools in other countries, particularly those with different climate conditions or mechanical ventilation systems. Factors such as age and condition of the school building, the type of windows and doors and the presence of any supplementary ventilation systems like air conditioning could all influence the ventilation rates and CO2 levels, but are not fully controlled in this study.

Simon: 19:50

For me, the study really reinforces the value of well-considered monitoring in classrooms to provide information to the users of those spaces, to the teachers to help them manage the space, and to the management of those spaces to identify areas of concern and implement actions to resolve it. It was not fully clear to me from what I could see of the study quite how bad bad was, and I'd have liked to have seen that because I think emotively at least it would help drive some action. But I can only imagine from what I've seen out there in the real world what do you think? Be interested to get your perspective on this? Are the average ventilation rates they saw across the schools of 5.3 litres a second per person anywhere near enough? This rate was higher in warmer weather at 6.8 litres a second per person, but as low as 3.8 litres per second, when the weather was down to five degrees, as they noted. Do you think that's enough? And finally, what should departments of education take away from this study, do you think? I'd be interested to hear your opinion on this.

Simon: 21:02

Congratulations to the authors. I think it was a really good study and I'll include it in the show notes. Obviously. I just want to finish really good study and I'll include it in the show notes. Obviously.

Simon: 21:09

I just want to finish up with something I was talking about on social media this week and it stemmed out of a couple of conversations I was having practically with some housing organizations that I'm working with at the moment trying to implement some workflows around how and when we test ventilation systems. The point I was making in my social media posts were that if you provide housing at scale as a private or social landlord, or you're delivering retrofits at scale, or you're a service provider to any of these at scale and you haven't started to genuinely develop the internal competency or looked at your supply chain's competency or started to work through your strategies of how you measure ventilation systems at scale that you might want to start paying attention whether correctly attributed to peter druckerer or W Edwards, demings or not, the you-can't-manage-what-you-don't-measure quote holds some truth when it comes to ventilation in homes, certainly, and whether as an organisation you're ready for it or not. Standards and guidance and schemes are all slowly moving in the direction of requiring decent assessment of ventilation systems. What's not well considered at the moment is just how capable the sector currently is, or its potential capacity is, to deal with this potential new reality. Reality, the truth is, we are not going to be in a position to properly assess all the ventilation we should or will be required to under these schemes and standards anytime soon. So, as an organization, if you're not starting that journey or at the very least started to develop a plan as to when and what gets measured, you're probably already behind the curve.

Simon: 23:13

As I said, I'm working with organizations like these every day and this is one of those challenges that we're dealing with right now and, don't get me wrong, no one's there yet but in recognising that we're starting to put into place, with these organisations, the policies and workflows to start moving in the right direction. Understanding the performance of ventilation is going to become a cornerstone of many processes within housing and retrofit many processes within housing and retrofit, from stock condition surveys to damp and mold surveys, retrofit assessments, void programs and much more besides and understanding and recognizing that not all approaches to measuring ventilation are the same and that we need to start developing strategies as to what assets to deploy when are going to be key. As I said, it's something that I'm working with people quite regularly for, and if you're in that position and want to understand what the what next is for you, look, you know where I am. So that's it for this week. I'm just getting back on the horse, really after my holiday.

Simon: 24:25

While I was away, there were some great podcasts out with Kareem Mandin talking about epidemiology, which I thought was fascinating. I had the amazing Brad Prezant on talking about occupational hygiene's role in indoor air quality and sustainability. In Australia, we had Stanton Wong, who's the president of of Reset, one of those organizations that is the benchmark really for low cost monitoring. That was last week and a really interesting episode, I think, and moving forward over the next couple of weeks, we've got some really interesting conversations around healthy homes in housing and also the social science of indoor air quality monitoring this no research about us without us piece, which I think is a really interesting direction to go in.

Simon: 25:15

Look. Thanks for listening as always. Before you go, can I ask a favour? If you enjoyed the podcast and you know someone else who might be interested, do spread the word and let's keep building this community. The podcast is brought to you in partnership with 21 Degrees, lindab, aeco, ultra Protect and Imbiote all great companies who share the vision of this podcast and are not here by accident. Your support of them helps their support of this podcast. Do check them out in the links and at airqualitymattersnet. See you next week.