The Ultimate Guide to Understanding Air Quality Data

As the world’s air pollution problem receives wider public attention, location-based and timely air quality data has emerged as a leading tool for businesses looking to engage and protect their consumer audiences.

But how exactly is air quality monitored? How do air quality sensors work? How does one read an Air Quality Index? We answer these and other common air quality data questions below.

1. What Exactly is Air Pollution?

Air pollution consists of both particles and gasses that, in high concentration, can be harmful to our health. The six most common air pollutants include:

  • Ozone (O3)
  • Sulfur Dioxide (SO2)
  • Carbon Monoxide (CO)
  • Nitrogen Dioxide (NO2)
  • Fine Particulate Matter (PM2.5)
  • Fine & Coarse Particulate Matter (PM10)

Individual air pollutants are also distinguished in terms of their origin. ‘Primary pollutants’ refers to compounds directly emitted by manmade or natural sources, such as PM and NOx pollution emitted by fossil fuel vehicles.

Where Does Air Pollution Come From?

We typically categorize the main sources of air pollution under 2 different categories:

a) Man-made sources, such as industry, construction, combustion processes (including fossil fuel burning, crop burning and man-made forest fires), and traffic.

b) Natural sources, such as naturally occurring wildfires, dust, pollen, or mineral ash.

Graphic of air pollutants

Pollen as an Air Pollutant

Pollen comes from the male part of many plants’ reproductive systems and is produced by any seed-producing plant type, (not just beautiful flowers as many believe). Allergy-causing pollen is produced by specific grass, weeds, or trees, and gets moved around by insects, wind, and water.

Although pollen is considered to be a Particulate, it’s a bit larger than the two commonly reported types of Particulate Matter (PM2.5 and PM10) so it gets treated a bit differently: pollen is often not included in traditional air quality reporting systems but rather referred to separately with pollen indexes based on pollen monitoring stations and pollen intelligence.

Air Pollution Sources Can be Local or Far Away

People can mistakenly assume they’re only at risk from air pollution while they’re next to an industrial plant, wildfire, or a busy road, but the reality is not that simple. Air pollution can travel great distances, even crossing oceans and entire continents. This means distant air pollution sources can impact your local air quality on a daily basis.

E.g. The orange stream displayed in the image below indicates mineral dust transported all the way from Sub-Saharan Africa to South America and across the Atlantic ocean: (!)

Moving pollution

Simulation of the Transport of Aerosols with GEOS-5. Credit: NASA

Air Pollution Moves Very Quickly

Unlike the weather, the quality of the air we breathe can vary on an hourly basis and in short distances such as from street to street. This dynamic variability makes tracking local air quality throughout the day an incredibly useful and important digital health tool, especially for people suffering from asthma, COPD, or other chronic respiratory and heart diseases.

Leveraging air quality data to visualize air pollution exposure enables people to understand the air they’re breathing and empowers them to protect themselves with appropriate action, such as limiting outdoor stay or timely medication usage.

2. How Does Weather Impact Air Quality?

On rainy days, most of the common air pollutants and pollen in the air are washed away, helping to increase the quality of the air. This phenomenon is called Wet deposition.

Similarly, wind can also help clear the air by preventing air pollutants from concentrating in particular areas. On the other hand, especially in the case of a wildfire, wind can also have the opposite impact by helping to spread toxic smoke and accelerate fire expansion.

The clear impact of weather on air quality, pollen, and wildfire behavior underlines why it is so important to consider weather and meteorological conditions when reporting on any type of environmental element. This is precisely why our team uses weather information (among many other data sources) to accurately calculate and predict air pollution (forecast & real-time).

3. What is the Impact of Poor Air Quality?

The World’s Greatest Environmental Threat to Health

The World Health Organization states that 99% of people live in areas where air pollution exceeds the organization’s air quality guidelines, which were made more strict in September 2021, and attributes 7 million premature annual deaths to air pollution exposure.

Boy in air pollution

Prolonged and even short-term exposure can particularly harm sensitive groups with pre-existing respiratory or cardiovascular conditions, the elderly, children, and pregnant women, however the stark reality is:

a) No-one is immune to the health impact of air pollution exposure

b) Air pollution exposure affects our bodies from head to toe – research has found air pollution to be linked to cancer, asthma, strokes & dementia, mental health, skin, bones, and more.

Huge Economic Cost

The cost of air pollution to the global economy is astronomical. The World Bank estimates the global economic impact of health damages caused by air pollution at $8.1 trillion each year, the equivalent of 6.1% of the global GDP. The World Economic Forum found air pollution costs every American an average of $2,500 in annual medical bills, with an annual $820 billion price tag for the national US economy.

Air pollution is so detrimental to national and global economic health that the UN created a new Wealth Index which factors the economic burden of air pollution on national economies.

Air Pollution Affects Different People in Different Ways

Individuals and population groups differ from each other in how they are impacted by high concentrations of different pollutants.  For example, a study across 16 Asian countries found a significant relationship between elevated PM2.5 pollution and child mortality, while another study associated higher ozone exposure during early pregnancy with premature births.

All of the 6 common air pollutants BreezoMeter reports on have the potential to harm people depending on the levels and length of exposure.

4. How is Air Pollution Usually Monitored?

As technology and science progress, air quality monitoring methods continue to improve as well. Here are a few common methods of measuring ambient air quality:

Governmental Monitoring Stations

The air quality sensors deployed by governments around the world at pollution monitoring stations are typically seen as the most reliable source of air quality information. Monitoring stations are an extremely expensive piece of equipment (costing up to $150,000 per station) and look like walk-in rooms containing different types of measurement. The stations are set up in specific locations and measure specific pollutants; each different pollutant will require a different sensor to monitor.

Air Quality Monitoring Station


Earth-observing satellites provide information about air quality measurements from above. The instruments deployed by the satellites observe air quality, which is then used by air quality managers and researchers looking to study the impact of air pollution on human health and agriculture around the world. Satellite sources of air quality information can be particularly useful when it comes to understanding the impact and spread of a wildfire from a bird’s eye perspective.

Satellite monitor

Low-Cost Sensors

In recent years, there has been a significant increase in the number of low-cost air quality sensors on the market, ranging in type from stationary to portable. Due to their affordability, these sensors are increasingly popular and can represent an abundant source of information where no government station may exist.

However, in-depth air quality data analysis and advanced QA is crucial to ensure a high level of accuracy of the measurements recorded by these low-cost air quality sensors.

Low Cost Sensor

5. What You Need to Know about Air Quality Indexes (AQI)

The average person will not know what a ‘200pbb’ concentration of a particular pollutant means for their health without context. Air Quality Indexes (AQIs) help us understand air quality data in a more intuitive way by categorizing pollutant concentrations, usually averaged across specific timeframes, according to specific scales.

For example, the US EPA AQI’s scale ranges from 0-500 while the Hong Kong government’s AQI ranges from 1-10.

Different AQIs can focus on different things depending on their objective  – such as the daily health threat to the general public vs. the annual risk level from exposure for example. This is one reason why some providers appear to show different air quality readings for the same location at the same time.

We explore why different AQIs used by different countries and providers sometimes show very different results in more detail here.

6. What are the  Challenges of Traditional Air Quality Monitoring?

Government Sensors Don’t Report in Real-Time

The main purpose of government-collected information is usually to inform regulatory planning and understand trends over time – as a result, their information tends to be reported as averages over time.

Information provided by government station sensors is extremely reliable and accurate for their purpose, but it was never intended for real-time decision-making. Most of the time, governmental information is reported with a delay of several hours. As we’ve seen, air pollution is extremely dynamic, so when used directly, the information isn’t actionable for the here and now.

Large Gaps Between Station Sensors

Government sensors are extremely accurate at their precise location, but there can be huge distances between these stations, affecting the reliability of air quality information at locations where no station is available. Air quality indexes that rely solely on station data can fail to account for pollutant presence in specific locations due to the gaps between stations.

For example, if you consider the impact of traffic on air pollution, it’s easy to understand how the particular location of a station sensor will affect the air quality reading you receive: If your closest station is based in a fairly non-industrialized area away from traffic but you live on a busy road, it’s unlikely the information you receive will help you understand the precise air quality at your home address.

Monitoring stations vs. BreezoMeter

Differences in the Number of Pollutants Measured

Furthermore, some sensors will monitor all 6 most common air pollutants, maybe even more, while some will monitor less. You can never be sure that an individual station is providing the full air quality picture unless you interrogate the data a little more deeply.

Difficult to Measure The Fire Impact

Wildfire smoke moves extremely quickly and unpredictably, and can often get missed by monitoring stations, which can only measure air quality at their exact location. If smoke passes near the station but doesn’t reach its sensors, it will not get reported. In addition, wildfires can also damage sensors and take them offline, potentially preventing reliable air quality reporting at the most crucial times.

Limited accuracy of Low-Cost Sensors 

Although the growing prevalence of low-cost sensors can represent a vast source of information, the readings measured by these sensors will differ dramatically depending on where exactly individual sensors are positioned. For example, the readings for a sensor placed by a busy road will be different from one based in the middle of a park, making it difficult to understand the precise factors contributing to air quality or – which readings are likely to be anomalies.

It’s also difficult to confirm whether or not individual low-cost sensors are calibrated as often as they need to be, an important factor when it comes to determining the level of accuracy.

Lastly, the individual reliability of a low-cost sensor can really depend on the particular type and model. For further reading, South Coast AQMD has put together a comprehensive report based on their laboratory evaluation of different low-cost air quality sensors.

7. How Does BreezoMeter’s Technology Work?

BreezoMeter adopts an innovative approach to air quality data reporting to solve all the above-mentioned challenges.

Multi-Layered Data Approach

We combine information from multiple data sources, which include government monitoring stations, low-cost sensors, meteorological data, satellites, land cover and live traffic information. This unique approach means we’re able to collect information even when one source becomes unavailable.

BreezoMeter air quality technology
  • We calculate air pollution in millions of geographical points around the world.
  • We validate and organize several terabytes of data each hour.
  • We deploy an array of algorithms, machine-learning and sophisticated modeling to calculate billions of pollutant concentrations in high accuracy on an hourly basis.
  • The end result is real-time air quality information that is accurate up to a micro-local scale of 5 meters/16 feet!

8. What about Indoor Air Pollution?

We’re not only exposed to air pollution when we’re outside – we can also breathe in toxic air at home, at work, or on the go, including during our daily commutes. For this reason, scientists today are increasingly speaking of an ‘indoor-outdoor air pollution continuum‘ to underline the fact that we shouldn’t focus on outdoor or indoor air pollution in isolation. Instead, we should consider the full 24-hour cycle of what an individual has actually breathed in.

How Can Air Quality Data Add Value to My Users?

Companies can capitalize on the rising awareness around air quality, in addition to emerging trends of digital health and personalization by integrating air quality data into their apps or connected products.

Tailored forecasts and dynamic environmental visualizations have proven themselves to be highly engaging as they help individuals ‘see’ and understand the air around them, and take action accordingly.

Such implementations of air quality data can enable new revenue streams and growth opportunities for businesses across a variety of industries:

  • Smart home brands can leverage air quality forecasts and insights to better manage wellness in indoor spaces, providing more value to their users through digital solutions that don’t require new hardware. This also applies to smart environment management systems in workplaces, classrooms, hospitals, and various other public and commercial buildings.
  • Marketing & advertising professionals can personalize & improve their targeting by reaching the most affected individuals at the right time, and by tailoring messaging according to real-time dynamic environmental conditions.
  • Healthcare companies can leverage air quality and other environmental data to inform research ventures and treatment plans to better engage patients and empower them in their own care to achieve improved health outcomes.
  • Smart mobility & automotive brands can enhance environmental protection during daily journeys with cleaner route planning and insights on the go that automate in-cabin air treatment systems or prompt motorists to engage AC or close the windows to minimize exposure to harmful air quality conditions on the road.

Explore more examples of how to utilize air quality data and environmental insights for product engagement & business growth right here.

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Amalia Helen
Amalia Helen

Content Lead @BreezoMeter. Passionate about environmental issues and the power of IoT, big data and connected technologies to solve the big problems of our day. Drop me a line by email or connect on LinkedIn.