TL;DR — The month of November is recognized as Clean Air Month in the Philippines, and to celebrate we’ve launched our Clean Air Month webinar series in conjunction with the Environmental Management Bureau (EMB) of the Department of Environment and Natural Resources (DENR). In the first installment, we tackled Air Quality Monitoring and Air Quality 101 where we discuss air pollution sources and receptors, considerations that come into play with air quality network design, and the ways that air quality data can be leveraged to work towards cleaner air for all. We’ve given an overview of our major takeaways below.

We recently held our first webinar in our Philippines Clean Air Month Webinar Series entitled “Air Quality Monitoring & Air Quality Sensors 101” put on by our Environmental Project Manager Dr. Alex Zare. Below we’ve recapped the key points from this webinar.

Climate change’s connections to air quality

With climate change accelerating, it is more important than ever to understand the intricate ties between air quality and climate change as we seek to improve both environmental crises. 

Climate change, which refers to the long-term shifts in temperature and weather patterns that occur, is largely due to greenhouse gases. These gases, including carbon dioxide, trap infrared radiation and increase the atmospheric temperature while simultaneously playing a role in worsening air quality.

The graphic above illustrates how greenhouse gases trap outgoing longwave, or infrared, radiation that leaves the Earth’s surface, creating a warming effect. Greenhouse gases can be produced both through natural processes, like volcanic eruptions, as well as through human activity, such as the burning of fossil fuels. (Image source: Wikimedia Commons)

Climate change — which may be indicated by higher ocean temperatures and sea levels, changes in the frequency, intensity, and duration of extreme weather events, and changes in ecosystem characteristics — has significant negative impacts on public health, water, agriculture, energy production, and ecosystems. 

Image source: C40 from the Smart Cities: Connected Public Spaces report

Fortunately, climate change and air pollution have some of the same solutions — such as reducing greenhouse gas emissions by moving away from fossil fuel combustion and moving to clean transport, buildings, and industries. For more information on the ties between air quality and climate change, and the ways that air quality co-benefits can be leveraged to incentivize climate action, read our blog here.

Air pollution: a silent killer

Air pollution is known as a silent killer due to the estimated 7 million premature deaths it causes each year — even higher by some estimates. The negative effects of air pollution significantly impact our daily lives and disproportionately affect disadvantaged communities, communities of color, children, the elderly, and those that are immunocompromised.

Air pollution may be categorized by its source, whether it is ambient or indoor, its origin, and its state of matter. Some significant air pollutants are as follows:

  • Particulate matter, which varies in size, composition, and origin including PM10, PM2.5, PM1, and PN, where the finest particles penetrate the deepest into our respiratory system
  • Nitrogen dioxide, which is a primary and secondary pollutant that irritates the respiratory system and can cause asthma attacks
  • Volatile organic compounds (VOCs), which refer to a group of chemicals that are released from burned fossil fuels and some household products like air fresheners and paints
  • Ground-level ozone, which is a secondary pollutant that forms from the interaction between NOx and VOCs in the presence of sunlight and is also a constituent of smog
  • Sulfur dioxide, which is emitted during industrial processes and from power plants and forms a precursor to acid rain

See our Air Quality Measurements Series blogs on particulate matter, nitrogen dioxide, and ground-level ozone here for more information on each key pollutant.

By measuring different types of air pollutants, we can arrive at a more complete picture of air quality in a given location. Read our blog here to examine case studies of ozone, particulate matter, and nitrogen dioxide air pollution in different cities.

Key questions regarding air pollution — and how air quality monitoring can help address them

By understanding the answers to key questions about air quality, we can better work towards effective air quality monitoring networks and a future of cleaner air.

Air pollution sources can either be stationary, like from a power plant, or mobile, such as from a vehicle or volcanic eruption. After primary pollutants are emitted into the atmosphere, some can react to form secondary pollutants.

Air pollution can travel over small or great distances as it moves from the source to the receptor, which may be the person breathing in the air or the air monitor. Considering who will be breathing in the air pollution, when, and for how long is important when determining the specifics of an air quality monitoring network design as well as when assessing the impacts of unclean air.

The next step is to actually measure how much pollution is in the air, which may be reported with various units such as parts per million, or communicated through indices such as the Air Quality Index (AQI), which makes it more readily understandable.

But how much air pollution is too much? While each country or state may have its own standards, such as the USEPA’s National Ambient Air Quality Standards (NAAQS) for the European Environment Agency’s Air Quality Directives in the EU, research also shows that there is no safe level of air pollution.

Air quality has traditionally been measured using federal reference methods (FRMs) and federal equivalent methods (FEMs), which are technologies that have been legally approved for the monitoring of the six criteria pollutants in the U.S. They use gravimetric or beta-attenuation methods (BAM) to determine air pollution levels, which can be very expensive.

However, non-FRM and FEM instruments such as low-cost sensors are increasingly important parts of air quality monitoring networks. They use an optical method to estimate particle count and size to arrive at air quality measurements, which is much more cost-effective.

Air quality can be measured using three different approaches: stationary, mobile, and personal monitoring. Read our blog for more information about different types of air quality monitoring technologies here.

The current state of air sensor technology

The figure above shows a visualization for the adoption of low-cost air sensors. In 2020, about 73,000 ambient air quality sensors were installed, and approximately 315,000 sensors are expected by 2025. With the improving performance of low-cost sensors, rapid adoption is expected.

As low-cost sensor technology continues to develop, the U.S. Governmental Accountability Office report recommends that the USEPA develop an air quality monitoring modernization plan to better meet the air quality monitoring needs of a variety of stakeholders. Read our blog regarding the GAO report here for more information.

Low-cost sensors have a wide range of use cases. Our sensors have been deployed in 70+ countries around the globe as part of community air quality monitoring networks, to assess air quality at schools, establish official air quality monitoring networks, assess the impacts of green infrastructure investment, and support existing networks in place.

Assessing the quality of air quality data

It is crucial to look at both measures of accuracy and precision when determining the quality of air quality data.

The image illustrates the difference between the measures of accuracy and precision. While accuracy involves the comparison of non-FRM/FEM devices to these reference monitors using the process of collocation, precision refers to the consistency of data points between devices. Both are important measures of data quality.

Collocation — which involves placing a reference device and low-cost sensor in the same location to compare their data — is an important part of ensuring data quality. For more on this topic, refer to our Guide to Accurate Particulate Matter Measurements with Air Sensors, as shown below.

The who, what, when, and where of air quality data

A variety of individuals benefit from access to air quality data. While regulators can use it to set enforceable standards or recommended guidelines, researchers, policy-makers, concerned citizens, and industries also leverage this data.

The question of how frequently monitors should collect data depends on the purpose of the network. While regulations tend to be based on hourly, daily, or annual averages, real-time data can be incredibly useful when looking at the rapid changes that can occur in air quality.

The when and where of air quality monitoring also depends on the purpose, but at its core should be where exposure is happening! If looking at human exposure in a certain area, air quality monitors would likely be placed at schools, parks, offices, and homes.

Understanding air pollution to work towards a healthier future

It is crucial to understand air pollution because this is the first step in ensuring that it can be measured and mitigated.

Hybrid networks and low-cost sensors play a crucial role in making air quality monitoring more accessible, scalable, local, and real-time, therefore increasing its impact.

Interested in measuring air quality for cleaner air, improved physical and mental health, and a healthier climate? Get in touch with our team to learn more about our Sensing-as-a-Service solution for governments, businesses, and community organizations, using our Clarity Node-S monitors and modules that do not depend on infrastructure like WiFi or power — making them especially resilient during environmental disasters.