TL;DR — As air quality researchers and managers uncover the harmful impacts of ozone air pollution, efforts are being made to fill in the gaps that exist in our global ozone monitoring infrastructure. which is sparse in many regions of the world. Our recent webinar looked at the global state of play for ozone monitoring — as well as the challenges that exist for effective ozone management —  and included insights from four panelists who brought their expertise in ozone research, modeling, and management. You can view the full recording of the ASIC workshop webinar here.

We recently held a virtual workshop entitled “Reliable Ozone Measurement at Scale: Applications of the Clarity Ozone Module for Air Quality Research, Modeling, and Management” where we were joined by over 200 attendees. With the recent release of the Clarity Ozone Module, we discussed the ways that our FEM-capable ozone monitor can be used in a variety of applications, including air quality monitoring and ozone modeling projects.

We were joined by panelists Owen Cooper, Gordon Pierce, Jessa Ellenburg, and Paolo Micalizzi to discuss the way that ozone monitoring plays an important role in better understanding, monitoring, and communicating air quality, at both the local and the global scale. All of the panelists' presentations were excellent — the following is a recap of the main takeaways from each of their presentations!

Leveraging the Tropospheric Ozone Assessment Report (TOAR) to assess the gaps in global ozone monitoring infrastructure

Owen Cooper, Senior Research Assistant at the Regional Chemical Modeling at Cooperative Institute for Research in Environmental Sciences at the University of Colorado discussed how ground-level ozone monitoring helps researchers assess surface ozone trends and quantify global human exposure.

Global air quality databases — such as the Tropospheric Ozone Assessment Report (TOAR), an initiative that Owen leads — are useful platforms for investigating large-scale ozone trends. The TOAR aims to produce up-to-date scientific assessments of tropospheric ozone’s global distribution and trends. It is the world’s largest database of global ozone metrics, using measurements from over 10,000 stations and providing open access data.

Owen discussed some of the issues that exist with the current state of ozone monitoring, with a major component of the problem being insufficient spatial coverage. A very small portion of the world’s population lives close to an ozone monitor. 

Even in areas like California and France with a relatively high number of ozone monitors, less than 10% of people live within five kilometers of an ozone monitor. The lack of coverage provided by the number of existing ozone monitors means that it is difficult to quantify human exposure to this harmful pollutant or accurately measure regional levels. (Image source: Owen Cooper)

In areas of the world that tend to have less air quality monitoring in place, ground-level ozone monitoring is even more sparse. In South and East Asia, Sub-Saharan Africa, and the Middle East, there are even greater disparities in ozone monitoring. 

The image above displays the number of ozone monitors per 100 million people, as compared to the overall population of the country, as represented by the size of the country on the map. Clear disparities exist between regions, with very few ozone monitors existing in South America, Africa, the Middle East, and Asia, as compared to the population in these areas — many of which already suffer from very poor air quality. (Image source: Mark Newman, Department of Physics and Center for the Study of Complex Systems, University of Michigan)

Most of the world’s population is exposed to levels of ground-level ozone pollution above the World Health Organization (WHO) guidelines on a daily basis — the most recent guideline of 60 μg/m3 (or 30 parts per billion) was introduced in 2021, lowering the recommendation from the previous 100 ​​μg/m3. According to a 2020 study, 80% of the world’s population that resides in urban areas is exposed to air pollution that exceeds 100 ​​μg/m3. Because this number was based on the previous higher WHO guideline, the percentage exceeding the current guideline is almost certainly higher.

The same study, which looked at air quality in 406 different cities, found that if ambient levels of ozone pollution had been below the WHO guideline of 100 ​​μg/m3, more than 6000 deaths per year related to short term exposure could have been avoided.

Ground-level air pollution exposure is tied to significant public health effects. According to the Global Burden of Disease efforts and based on WHO metrics, 2.3 million deaths were attributable to air pollution in 1990, with 91% of them attributed to particulate matter and 9% to ground-level ozone. By 2019, this number increased to 4.5 million, with 92% due to particulate matter and 8% due to ozone, meaning about 360,000 deaths were linked to ground-level ozone pollution.

According to 2019 data, approximately 11,230 deaths are attributable to ambient ozone pollution in Africa, with approximately 1.1 million deaths being attributable to all air pollution. However, because of a lack of ozone monitoring, much of this information is based on satellite monitoring, rather than monitors on the ground — demonstrating the need for more reliable ground-level ozone monitoring to truly understand the impact of this pollutant.

The Health Effects Institute also finds that out of the top ten countries with the highest ozone exposures globally, nine of them are in Asia or the Middle East, where relatively few monitors exist, highlighting the need for expanded ozone monitoring in these regions as well as globally.

While projects like TOAR can help harmonize data from a range of sources and provide a global perspective on air pollution trends, they rely on ground-level ozone monitoring to populate their databases. A higher density of ozone monitoring is needed in many areas around the world so that human exposure can be more accurately quantified, as a first step to lowering ground-level ozone levels and improving global public health.

Colorado Case Study: The current state of ozone monitoring, and limitations that could be addressed with additional ground-level ozone monitoring equipment

Gordon Pierce, Technical Services Program Manager in the Air Pollution Control Division at the Colorado Department of Public Health, presented on the current state of ground-level ozone monitoring in Colorado.

Despite notable reductions in anthropogenic ozone pollution in the area of Denver, Colorado, it remains designated as a non-attainment area for ground-level ozone pollution with high ozone levels coming from both anthropogenic and natural sources.

Much of the reduction in ozone pollution that has occurred in recent years has been due to regulations put into place on vehicle emissions and oil and gas development since these compose the major anthropogenic sources of ground-level ozone. 

However, the “background” concentrations of ozone remain an issue — that is, ozone coming from both natural sources and drifting in from out of state. Ozone originating from these sources is much harder to control than that coming from local anthropogenic sources and makes reducing overall ozone levels a significant challenge. Exceptional events, such as stratospheric intrusions and wildfire smoke, also make pollution harder to control. For more information on how wind and other climatic patterns can cause air pollution originating in one area to affect air quality elsewhere, read our Air Quality Measurements Series: Wind Speed and Direction blog

Colorado has 21 ozone monitoring sites operated by the Colorado Department of Public Health and Environment across the state, in addition to networks operated by various federal agencies, tribal and local agencies, and private operators. However, this still translates to limited coverage based on the geographical area and population of the state.

The image above displays the number of ozone monitoring sites in 2021. Though ozone monitoring sites exist across the state of Colorado, many regions of the state lack any monitoring. With these gaps in monitoring coverage, quantifying overall ground-level ozone levels, as well as human exposure, becomes difficult. (Image source: Colorado Air Pollution Control Division)

Short-term monitoring is often used to identify areas where longer-term or supplemental monitoring may be needed, and it is performed every year in different areas to provide baseline information on ozone levels. However, short-term monitoring only provides a one-time snapshot of air pollution levels, and this data is not immediately available to the public, so it is not as useful as data from a long-term monitoring site.

Gordon shared that there is a lack of information on potential high ozone concentration areas, like the Front Range foothills, where increasing population, complex terrain, and a lack of ozone monitoring coupled together create cause for concern. Sparse ozone monitoring coverage also creates issues for forecasting ozone levels and public dissemination of information that is necessary to effectively protect public health. 

While the CDPHE would ideally invest in ozone monitoring for underrepresented areas like the Front Range foothills, it would not be feasible to do so with FEM technology. Reference-grade monitoring technology poses a number of challenges when looking to deploy dense air quality monitoring networks or measure air pollution in remote areas —such as the need for a temperature-controlled environment and the significant overhead associated with managing and running QA/QC for these technologies.

Gordon expressed that having affordable monitoring equipment that produces acceptable data is necessary would be hugely helpful to overcome these ozone monitoring challenges. Especially in the environmental conditions of Colorado, having weather-tolerant technology is a must, in addition to it being autonomous, solar-powered, and having some sort of cellular, WiFi, or satellite connectivity. It is also important data coming from this monitoring equipment can be displayed in a meaningful way to the public.

While ozone monitoring in Colorado exists, improving spatial coverage — especially in geographical areas with sparse coverage — with affordable, durable monitors that produce high-quality data is key to better managing ozone pollution and protecting human and environmental health.

The Global Ozone (GO3) Project and how ozone monitors produce accurate, high-quality data

Jessa Ellenburg, Director of Educational Outreach, joined us to share her ozone expertise on behalf of 2B Technologies. To learn more about ground-level ozone as a pollutant and ozone monitoring technology, read Jessa’s guest blog in our Air Quality Measurements Series.

The Global Ozone Project, or GO3, is a project led by 2B Technologies where ozone monitors are installed at schools around the world, allowing students and teachers to collect data to study ground-level ozone. The project has sent ozone monitors to 112 schools in 26 different countries over the past 10 years that it has been conducted.

The GO3 Project uses 2BTechnologies’ ozone monitor rather than ozone sensor technology to ensure the most accurate data possible. These monitors are based on UV absorbance and can produce accurate data for many years with little intervention, making them a great tool for both experts and nonexperts around the world.

UV absorbance monitors are considered the gold standard for ozone monitoring and are recognized as a federal equivalent method (FEM) by USEPA. As a brief overview, the technology functions via two basic phases:

  • In phase 1, ozone is scrubbed from the air and the intensity of light passing through the air is measured with no ozone presence.
  • In phase 2, the valve switches and ozone passes through, and the difference in light intensity which passes through the air is measured.

For a more in-depth explanation of how UV absorbance ozone monitors work, watch 2B Technologies’ video here.

The calculation which arrives at the ozone concentration makes use of the fundamental knowledge of how much light an ozone molecule blocks, which is an absolute value, thereby contributing to the accuracy of ozone monitors. In contrast, ozone sensors rely on electrochemical components that get consumed over time, thereby affecting the sensitivity and baseline drift of the technology. Ozone sensors have to be replaced on a regular basis to account for this.

By making use of ozone monitor technology, projects like GO3 can collect accurate, long-term ground-level ozone monitoring data and make use of it to involve the community in air quality awareness and spread awareness about ground-level ozone pollution.

How Clarity’s Ozone Module paves the way for ground-level ozone characterization as part of a hybrid network

Our Chief Technology Officer at Clarity, Paolo Micalizzi, concluded the webinar by covering our Ozone Module technology and how it can be used to effectively monitor ground-level ozone.

With our release of the Node-S 2 in October, Clarity now provides a platform for the accurate measurement of a variety of air pollutants. One of our most exciting new offerings, our Ozone Module uses 2B Technologies’ ozone monitoring technology to create an FEM-capable solution for regional characterization.

Paolo shared that because ground-level ozone is a secondary pollutant, it tends to be more uniformly distributed spatially than primary pollutants like particulate matter. Thus, it is more important to have very accurate regional monitoring for ozone, compared to indicative block-by-block monitoring as would be more useful with primary pollutants like particulate matter and nitrogen dioxide. 

With the use of an ozone monitor in conjunction with other pollutant monitoring technologies, one can create a hybrid network that is dense for parameters with high spatial variability and more sparse, yet extremely accurate, for uniformly distributed pollutants like ozone. As an FEM-capable monitor, the Ozone Module produces high-quality, accurate data. Even when the monitor is not specifically used for regulatory purposes, its high data accuracy can inform if there are potential air quality issues that need further investigation or follow-up. 

One successful hybrid network is run by our partners at JustAir in GrandRapids, Michigan. The JustAir network consists of 11 Node-S devices deployed across the city to monitor particulate matter and nitrogen dioxide, with one ozone module for regional characterization. This network design allows them to study the significant air quality disparities that exist for disadvantaged communities within the city, and simultaneously monitor a variety of pollutants. 

Our partners at JustAir in Grand Rapids, Michigan monitor particulate matter, nitrogen dioxide, and ground-level ozone using a combination of Clarity’s Node-S sensors and one Ozone Module to arrive at a more complete picture of air quality in the city. 

The monitoring technology is also useful for providing the public with additional information for air quality in their area. Because agencies cannot put out regulatory monitors everywhere — as they are expensive to purchase and maintain, among other barriers — the Ozone Module can provide more general, accurate data to the public as well.

Making ground-level ozone monitoring a part of your monitoring network

Measuring ground-level ozone with an accurate, scalable ozone monitor allows ozone pollution to be better understood by scientists, monitoring agencies, and the public alike. We hope to see the Ozone Module used to fill some of the gaps that exist in ozone monitoring infrastructure around the world, allowing us to achieve a more accurate and complete picture of human exposure to this harmful pollutant.

By including ozone monitors as part of a hybrid monitoring network, a variety of pollutants can be measured, both at a block-by-block level and a regional level, to more fully characterize air quality in the given area.

To find out more about Clarity’s Ozone Module, view our press release and Ozone Module product page for more detailed information. Contact us here to learn more about how you can include ozone monitoring in a Clarity air quality monitoring network.

You can view the full recording of the ASIC workshop webinar here.