Latest / Internet of Things with Fexingo: Connected Devices, Sensors, and Industrial IoT / How IoT Sensors Are Monitoring Air Quality Inside Schools
Transcript
- Lucas: So, when we think about IoT sensors in buildings, most of the conversation revolves around energy efficiency or security. But there's this quieter, maybe more impactful use case that's been scaling a lot faster than people realize: indoor air quality monitoring in schools. Luna: You mean like CO2 sensors and that sort of thing? I've seen a few headlines about schools doing that post-pandemic, but I didn't know it was actually scaling. Lucas: It is, and the numbers are pretty striking. Baltimore City Public Schools, for example, installed over 2,000 wireless sensors across 120 buildings starting in 2024. And these aren't just CO2 sensors — they measure PM2.5, which is fine particulate matter, and VOCs — volatile organic compounds from cleaning supplies, markers, that kind of thing. Luna: When you say wireless, what protocol are they using? Is this LoRaWAN, Wi-Fi, something else? Lucas: Mostly LoRaWAN, because schools are huge buildings with thick walls and basements where Wi-Fi doesn't reach. The sensors are battery-powered and report every 15 minutes to a central dashboard. The whole system costs about 150 dollars per classroom for the hardware, plus a small monthly fee for the cloud platform. That's cheap enough that a district can roll it out without a bond referendum. Luna: And what are they finding? I assume the data is pretty eye-opening. Lucas: It's honestly alarming. In Baltimore, the pilot showed that CO2 levels in occupied classrooms regularly hit 2,000 parts per million by third period. For context, outdoor ambient CO2 is around 400 ppm. At 1,000 ppm, most people start feeling drowsy. At 2,000, cognitive function measurably drops — like, test scores suffer. One study from Harvard showed that decision-making performance declines by 50 percent or more at CO2 levels above 1,400 ppm. Luna: Wait — so kids are sitting in rooms with air that's literally making them dumber, and nobody knew until the sensors went in? That's wild. Lucas: Exactly. And it's not just CO2. The PM2.5 sensors picked up spikes near busy roads during drop-off and pickup times. The VOC sensors flagged elevated levels right after custodians cleaned with certain products. The district was able to adjust HVAC schedules and change cleaning protocols based on real data instead of guesswork. Luna: So the sensors are basically giving facilities managers a live feed of what's in the air. But who's actually watching that feed? Is it automated alerts, or does someone have to sit and stare at a dashboard? Lucas: It's mostly automated. The system sends a text or email alert when any sensor crosses a threshold — say, CO2 above 1,500 ppm for more than 30 minutes. The facilities team can then remotely increase ventilation or, in older buildings, open a window. Some districts have tied the sensor data directly to the building management system, so the HVAC adjusts automatically. Luna: That's the ideal — a closed loop. Sensor detects bad air, system responds without human intervention. But I'm guessing a lot of schools don't have the fancy HVAC to do that. Lucas: Right, and that's where the interesting partnerships come in. Baltimore worked with a local HVAC startup that retrofits older units with IoT controllers — basically a smart thermostat on steroids. They added sensors to each unit's return air duct, so the system knows exactly which classrooms need more fresh air. It's not as sophisticated as a full variable air volume system, but it cut CO2 exceedances by 80 percent in the pilot schools. Luna: And did they see any health or attendance improvements? That's the bottom line for school boards. Lucas: Yeah, and that's the most compelling part. In the pilot buildings, absenteeism dropped by 12 percent compared to control schools without the sensors. The district estimates that translates to about 4,000 fewer missed school days per year across the pilot group. When you factor in that schools are funded based on daily attendance — at least in many states — the system pays for itself in less than a year. Luna: Okay, that's a real return on investment. And it's not just Baltimore, right? Other districts are doing this too? Lucas: There are pilots in about two dozen states now, from California to Maine. The EPA is also considering new guidelines that would recommend or require continuous indoor air quality monitoring in schools by 2028. If that happens, this could go from a niche pilot to a nationwide mandate, which would be a huge tailwind for the sensor manufacturers and the IoT platforms. Luna: I want to ask about privacy — because you're putting sensors in classrooms full of kids. Are there any concerns about surveillance, or is it just air data? Lucas: It's a fair question, and the districts I've looked at are careful to emphasize that these sensors only measure gas concentrations and particulate matter. No cameras, no microphones, no way to identify individual students. The data is aggregated at the classroom or building level. Still, some parent groups have raised concerns about data security — who owns the data, where it's stored, how long it's kept. Those are valid conversations, and the best districts have been transparent about their policies. Luna: Yeah, I can see that being a sticking point. But if the trade-off is better health and higher test scores, it seems like a no-brainer for most parents. Lucas: And look, this kind of conversation — where we're digging into a real-world deployment with specific numbers and outcomes — that's exactly the kind of thing that makes this show useful, I think. If today's episode gave you something you can use — whether it's a talking point for a PTA meeting or just a clearer picture of how IoT is quietly improving everyday life — the way we keep making these episodes ad-free is through listener support. It's buy me a coffee dot com slash fexingo. Luna: Yeah, completely agree. It's a small way to ensure we can keep diving into these niche but important topics without any sponsor influence. Lucas: So back to the school air quality story — one more thing I found really interesting. The sensors also revealed that some classrooms had no measurable CO2 problem because the windows were always open. But that created a new problem: outdoor pollution came in. In one school near a major highway, the PM2.5 levels inside were actually higher than outside during rush hour. Luna: So the solution isn't just 'open a window' — it's about having the right data to make the right trade-off. That's where IoT becomes indispensable. Lucas: Exactly. The sensors give you the information to decide: do we need to filter the intake air, or can we just increase mechanical ventilation? And in older buildings where you can't easily retrofit, sometimes the answer is a standalone HEPA filter with its own IoT sensor that turns on when PM2.5 spikes. Luna: Are there any open-source or low-cost sensor options for schools with very tight budgets? I know some districts literally can't afford 150 dollars per classroom. Lucas: There are a few projects — one out of Carnegie Mellon called the 'Air Quality Egg' that costs about 60 dollars per node. But the trade-off is accuracy. The cheap sensors drift over time and need calibration. The 150-dollar units from companies like Airthings or uHoo are more reliable and have longer battery life. Some states like California have grant programs specifically for school air quality monitoring, so the cost is often covered. Luna: That's good to know. So what's the next frontier for this? Are we going to see sensors in every classroom by 2030, or is that optimistic? Lucas: I think 2030 is realistic if the EPA guidelines go through. What's really interesting is that some districts are already combining air quality data with occupancy sensors to optimize HVAC even further — only ventilating rooms that are actually occupied. That's where the energy savings really add up. So it's not just a health play, it's a sustainability play too. Luna: So the sensors are pulling double duty: healthier kids and lower energy bills. That's a hard argument to lose. Lucas: It really is. And the beauty of IoT is that once you have the sensor network, you can add more use cases over time. Some schools are now adding noise level sensors to monitor classroom activity, or temperature sensors to detect overheating. The infrastructure is the same — just a different endpoint. Luna: Alright, I'm sold. For any school administrators listening — if you haven't looked into this yet, the data is pretty compelling. Lucas: That's the takeaway. Next episode we'll look at how IoT is being used to monitor water quality in public swimming pools — another hidden sensor application you probably haven't thought about. Luna: Gross, but important. See you next time.