Overview
In September 2025, the City of Ann Arbor launched a network of ten solar-powered air-quality monitors placed across the city. These stations measure fine particulate matter (PM2.5), nitrogen dioxide (NO₂), and ozone (O₃), with results translated into EPA-standard Air Quality Index (AQI) categories ranging from “Good” to “Hazardous.”
Residents can track local conditions through a publicly available online map and subscribe to receive station-specific alerts when air quality reaches “Unhealthy” levels. The city also maintains an interactive dashboard and a downloadable dataset covering all measurements collected since the first station was installed in June 2022.
- The timing of the rollout reflects increasing concern about smoke and ozone events in Michigan. Washtenaw County issued multiple air-quality advisories during the summer of 2025, including a three-day alert in early August tied to wildfire smoke drifting into the region.
- The project was developed in partnership with Clarity Movement and is managed by the Office of Sustainability and Innovations. It represents Ann Arbor’s first hyperlocal, real-time monitoring system designed specifically for public use, rather than for regulatory compliance under the Clean Air Act.
While the Clarity sensors are not EPA-certified reference monitors and cannot be used in permitting or enforcement, they add a layer of transparency and local visibility. By complementing the state’s regulatory-grade instruments, the network provides residents with practical, real-time information to guide decisions about outdoor activity and health protection.
Transcription
David Fair: This is 89.1 WEMU. And today, we're going to talk sun and air quality, but probably not in the way you think. I'm David Fair, and welcome to this week's edition of Issues of the Environment. Last month, the City of Ann Arbor launched an innovative program to better inform residents about the health of the air they're breathing. It placed a network of 10 solar-powered air quality monitors around the city. Now, what can it tell you? How can it make a difference in future protection measures? Well, let's find out. Our guest today is Sean Reynolds, and Sean is Senior Analyst in the city's Office of Sustainability and Innovations. And thanks for making time today, Sean! I appreciate it!
Sean Reynolds: Yeah, thank you for having me!
David Fair: As I was reviewing this program, it occurred to me I never thought much about how our air was being monitored or who was gathering the information. I know where to look to find out if we're having an ozone action day or under air quality alert. Usually, there's messages from the state, from NOAA, and even the Southeast Michigan Council of Governments will put out information. This monitoring program is all about resident access for people like you and me, right?
Sean Reynolds: That's right, yeah. We really are trying to narrow it down to get really local, very small-scale air quality data for individual parts of our city.
David Fair: I'm sure it makes perfect sense to you, and maybe I'm a bit off, but it seems like an out-of-the-box kind of concept. Where did the idea come from?
Sean Reynolds: Yeah. So, actually, this is one of the actions that's outlined in the city's A2Zero plan, which is our living plan to achieve community-wide carbon neutrality in a just and equitable way by the year 2030. One of the strategies under that plan is to enhance the resilience of our people and our place, and part of enhancing resilience is making sure that we know what kinds of impacts are happening to our city and our people in our place because of climate change. And so, one of the actions in that plan is to monitor both our air quality and our water quality. So, here we are today with this air quality network.
David Fair: Now, I don't know if you heard, but a prominent world leader in an address to the United Nations said, "Countries that prioritize green energy were going to Hell." And, you know, I'd really hate that for Ann Arbor. In quality control testing, were there any issues with the monitors because they're solar?
Sean Reynolds: We have not had any issues with these so far, no. We had one that stopped working because I think a bug crawled up into the inside of it. I think it was a spider, and it made a a web up in there. So, that was a little bit of an issue, but we have now had any other issues with these so far, especially not with the solar power. It has been working great so far.
David Fair: Well, conversely, are there advantages in reliability and energy usage in utilizing solar monitors?
Sean Reynolds: Yeah, it's definitely an advantage for energy usage. It is much more green, as you mentioned earlier, to be using these solar panels. It also is an advantage because it means that we can place them really wherever we want. We're not limited by finding a spot that has access to an outlet for it to be plugged directly in. It can go really wherever we want it, as long as it gets good sunlight.
David Fair: This is 89.1 WEMU, and our Issues of the Environment guest today is Sean Reynolds. He is Senior Analyst in the City's Office of Sustainability and Innovations. There's a lot that goes into determining the health and the quality of our air. So, what components are actually being measured in this network of 10 solar monitors?
Sean Reynolds: Yeah. So, every single one of these 10 monitors is measuring particulate matter of 2.5 microns or less. So, particulate matter is basically small particles of things that are floating around in the air, so if you think of what has been causing poor air quality in this area most often most recently is wildfire smoke from wildfires that are happening in Canada or other parts of the United States So, those smoke particles are particulate matter. The 2.5 microns or less is just referring to the size, the diameter, essentially, of those particles that are floating around in the air. You can also measure particulate matter of 10 microns or less. But the 2.5 microns or less are really the ones that are more likely to cause health impacts for humans, because they're small enough that our lungs aren't able to as easily filter them out when we're breathing. So, all of the measure of that particulate matter, they also all measure nitrogen dioxide, which is a common air pollutant from the combustion of fossil fuels in things like your car engine or your lawnmower engine. And then, we also have one of the monitors, the one that's on the roof of City Hall, also have an ozone monitor attached to it. You mentioned ozone earlier. That is a pollutant that can form in the atmosphere from the reaction of sunlight uh... With some other chemicals that can be released, again, typically, from the combustion of fossil fuels. And then, we also have two of the monitors, so the one at Buhr Park and the one at Northside Community Center. Both also have a weather module. And so, that is measuring wind speed and wind direction, as well as the relative humidity atmospheric pressure and temperature in the surrounding area .And those are there because all of those kind of weather factors can have play a really big role in what air quality is. Typically, if you see it is a warmer or more humid day, you might be more likely to be certain air pollutants than on cooler days.
David Fair: So, what are the biggest air quality issues for fall and winter after we endured such high temperatures, ozone creation and wildfire smoke this summer?
Sean Reynolds: Yeah, that's a great question! Typically, from the data that we've seen so far, we've actually had these monitors up for a little while. We last month launched the dashboard, but the monitors have been up for little while. And so, we haven't seen particularly poor air quality for the most part in these kind of fall and winter months, which is great. I would expect, if we were to see it, it would probably be that nitrogen dioxide would be more likely or possibly the particulate matter, because you can still sometimes have like wildfires in the winter. It's less common, but it can happen.
David Fair: Tou mentioned the dashboard, which is available online, but I'm wondering. Is there also an app that we could carry around on our phones too?
Sean Reynolds: There's not an app, unfortunately, but the dashboard is accessible on your laptop or phone or iPad or whatever device you may have. If you go to a2gov.org/airquality, you will see we've actually embedded the dashboard right onto that page. And then, there is also a link further down the page to go directly to the dashboard, if the embed isn't working for whatever reason. And again, that should work on your phone, as well as your your computer or other device.
David Fair: And again, it provides real-time monitoring of air quality levels. Will it also explain to us what actions need to be taken if in fact we are in an unhealthy range?
Sean Reynolds: So, it has a little bit of information about the potential health impacts. We really encourage folks to go to the EPA--U.S. Environmental Protection Agency's--website. They have a really great bevy of resources that you can look into that have information about the different pollutants, some more information about what is particulate matter 2.5, for example, and the potential impact and also recommendations, in terms of "Should you go outside? Should you wear a mask?" That sort of thing. So, that website has a lot of that information. And so, we didn't feel the need to duplicate what was out there, so we just kind of direct folks in that direction.
David Fair: Our Issues of the Environment conversation with Sean Reynolds once again continues on 89.1 WEMU. Sean is Senior Analyst in Ann Arbor's Office of Sustainability and Innovations. And I'm glad you mentioned the EPA. While this is an innovative and hyper-local program, as we as city residents monitor the air around us, a bit of faith is required they're accurate and reliable. Are these monitors EPA-certified?
Sean Reynolds: [00:07:52] So, these are certified by the U.S. EPA and U.S. Forest Service for use on their FireNow map, I believe it is called....AirNow Fire and Smoke map. Apologies. So, that is the official map from the U.S. EPA and the USDA Forest Service. That has particulate matter data on it. So, they are certified for that particulate matter. I do not believe that they are actually certified for the nitrogen dioxide, but a reference kind of calculation has been applied to them based off of reference stations. So, for example, there is a reference station over in Ypsilanti that is certified by the EPA for all of the air quality or air pollutants that it measures. And so, these have been kind of certified off of that one.
David Fair: Well, you mentioned at the outset that this is an initiative that is part of the grander A2Zero initiative. And I'm curious. While we are able to track air quality in real time, how does this become a longer-term aid in the city achieving its carbon neutrality goals?
Sean Reynolds: So, like I mentioned earlier, we really wanted to be able to measure what is going on with our air quality in order to build resilience, because, really, we can't make changes if we don't know what's happening. So, this really serves to give us data on what our air quality looks like and really see what are the pollutants that we're seeing most often and when do we see them. And again, it's largely been particulate matter in those summer months when those wildfires are happening. And so, obviously, we can't really make a direct impact on whether it's wildfires are happening in Saskatchewan or Alberta living here in Ann Arbor, Michigan. But we can start thinking about ways that we can build resilience in the community to those effects that we can't really necessary have an impact on. So, thinking about creating this dashboard, for example, which is a great way for folks to go and sign up for alerts when the air quality gets to a certain level, so that you just get an email that tells you, 'Hey, the air quality is at AQI level 4," which is considered unhealthy, potentially for all folks. And so then, you can go to the EPA website and look at, "What does that mean for my health? Should I wear a mask? Should I not go outside at all today?" and really be able to make those informed decisions. It's also really helpful for us as we are moving towards the carbon neutrality goal in the A2Zero plan to be able to see what our air quality looks like now versus, for example, in 2030 when, hopefully, we have met that goal of carbon neutrality, and see if air quality has changed in any way from all these other actions that we are taking. And if we see that has changed in a positive way, then that's great. But we might also feed maybe there are decreases in air quality from something that we're doing. And so, that would allow us to then say, "Okay, well, this clearly is maybe working in one way, but it's having an impact on the air quality here. So, what is a thing that we can do to change that to address that issue that we're seeing?"
David Fair: Well, I think it's a rather exciting program, and I appreciate you telling us all about it and taking the time to do so!
Sean Reynolds: Yeah, no problem! Thank you again for having me on!
David Fair: That is Sean Reynolds, Senior Analyst in Ann Arbor's Office of Sustainability and Innovations and our guest on Issues of the Environment. For more information on today's topic, pay a visit to our website at WEMU.org. Issues of the Environment is produced in partnership with the office of the Washtenaw County Water Resources Commission, and you hear it every Wednesday. I'm David Fair, and this is your community NPR station, 89.1 WEMU-FM Ypsilanti.
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