Access to accurate air quality data can influence everything from public health decisions to climate research and policy. It’s critical that air quality data is trustworthy.

IQAir is dedicated to delivering real-time, reliable, high-quality air quality information to people and organizations around the world. Air quality data must be available in real-time and easily understood, so that everyone can immediately act and protect themselves from the serious health threat posed by air pollution.

This commitment drives a comprehensive quality assurance process on the AirVisual platform—an approach grounded in scientific rigor, transparency, and collaboration. Accurate sensors are selected, validated, and calibrated to ensure that everyone has dependable, free access to air quality information at their fingertips.

For a deeper look at the quality assurance processes, hear directly from Dr. Christi Chester Schroeder, IQAir’s Director of Air Quality Science.

IQAir’s approach to quality assurance

IQAir both manufactures air quality monitors and hosts AirVisual, a comprehensive, freely accessible air quality data platform. This approach to quality assurance is built on a foundation of scientific precision and continuous improvement. 

AirVisual Outdoor air quality monitors undergo a combination of rigorous laboratory testing and real-world performance evaluations; the AirVisual Outdoor’s high accuracy has been verified by the Swiss Federal Institute of Metrology (METAS). Each sensor must meet strict criteria before being approved for deployment on the AirVisual platform, ensuring that every data point shared is rooted in reliability from the start.

The AirVisual platform aggregates air quality data from both low-cost sensors and reference monitors, publishing data from over 30,000 air quality monitoring stations in more than 140 countries and 15,000 cities around the world. Roughly half of the data on the AirVisual platform comes from low-cost sensors, and the other half from government-operated monitors.

Low-cost sensors, like the AirVisual Outdoor, are usually deployed by individuals and organizations. The AirVisual platform is sensor-agnostic; there are approximately ten different low-cost sensor types on the platform.

Regardless of the source and whether air quality contributors maintain one sensor or a network of sensors, all sensors undergo verification and calibration.

Regardless of the source and whether air quality contributors maintain one sensor or a network of sensors, all sensors undergo verification and calibration. IQAir employs a combination of automated algorithms and manual review processes to detect and correct anomalies in real time, maintaining consistency and accuracy across the network.

Sensor validation

Sensor validation is a critical first step in IQAir’s quality assurance process. Before devices are added to the AirVisual platform, they must undergo extensive evaluation to ensure they meet the required standards for accuracy and reliability. 

The location and placement of every AirVisual Outdoor sensor is manually verified through photos before it is added to the platform, assuring that the sensor is both outdoors and in an appropriate location. 

Sensors are assessed for their ability to produce consistent, precise measurements over time, minimizing data gaps and maximizing data completion.

All sensors are assessed for their ability to produce consistent, precise measurements over time, minimizing data gaps and maximizing data completion. That means they must: 

• Maintain a stable power and network connection for equal to or greater than 3 days, with consistent data. 

• Have a reasonable correlation with surrounding stations.

• Publish air quality data at least on an hourly basis, or shorter when possible.

Devices that demonstrate strong correlation with surrounding stations and maintain stability in challenging environmental conditions are selected for publication. Those that don’t meet those standards won’t be published. 

Sensor calibration

Ongoing sensor calibration assures that air quality data published on AirVisual is consistent and error-free. These ongoing checks help identify any drift or discrepancies, allowing for timely adjustments. 

Ongoing sensor calibration assures that air quality data published on AirVisual is consistent and error-free.

With multiple sensor types publishing data on the AirVisual platform, it is important that raw data is assessed, cleaned, and calibrated before publication. Quality control procedures are incorporated into the data pipeline that mathematically assess individual data points, evaluating whether a station's data is so outlying that it may be considered an outlier. 

Some criteria may trigger a data quarantine or a station being unpublished. Examples of criteria that may flag data for a review and quarantine include:

• Reporting less than five hours of historical data.

• Data point exceeding pollutant specific designated concentration threshold.

• A data outlier detected relative to other area stations.

In some cases, a sensor may need to be unpublished entirely: 

• Reporting the same concentration value for 24 hours.

• Reporting concentrations of 0 for more than 12 hours.

• Stopping data reporting for six hours.

While automated quality control procedures are continuously running on the platform, users can also report when they see issues with a station through the AirVisual app.

Advanced data checks

Automated and manual QC processes identify and correct sensor reading anomalies in real time.

Both automated algorithms and manual review processes work in tandem to detect and correct anomalies in real time, minimizing the potential for errors and ensuring data consistency. These checks continuously monitor incoming data, flagging any irregularities such as sudden spikes or unexpected trends – departures from the historical data or weather conditions – that could signal equipment malfunctions or environmental interference.

Environmental compensation

Atmospheric factors such as humidity and temperature can influence sensor readings. For instance, high humidity might result in low-cost sensors overreporting PM2.5 concentrations in an area. 

To counteract this, IQAir employs correction algorithms that automatically adjust sensor output to account for these environmental variables.

These algorithms use real-time environmental data to correct for the effects of fluctuating conditions, ensuring that air quality measurements remain consistent and reliable across a wide range of climates. 

Commitment to transparency and collaboration 

IQAir is committed to openly sharing quality assurance methods, validation processes, and results. This ensures that everyone can trust the integrity of the data provided on the AirVisual platform. 

IQAir actively collaborates with governments, researchers, and NGOs to independently verify the data quality. 

Partnerships with organizations like the United Nations Environment Programme and Greenpeace allow IQAir to validate methods and contribute to the broader global conversation about air quality monitoring (1). 

IQAir also works with networks ranging from the Main Astronomical Observatory (MAO) in Kyiv, Ukraine to air quality sensor researchers in Ghana to advance everyone’s global understanding of air quality data.

These collaborations help continually refine and improve IQAir systems to better support public health and inform environmental policy worldwide.

Community Stories: Real People Powering Global Air Insights

The AirVisual platform is more than a technical network—it’s powered by a global community of educators, environmental advocates, and everyday citizens using data to drive change. IQAir is proud to spotlight some of the many contributors making a difference:

• Permian Health’s air quality crusade in Gambia: A rural health initiative using real-time PM2.5 data to inform public health and drive national air quality policy.

• WWF-Pakistan: A 15-city sensor network providing real-time data to raise awareness and inform environmental policy.

• Clean Air One Atmosphere in West Africa: A citizen science project using IQAir sensors to educate, engage schools, and identify pollution hotspots.

• Community centers in Michigan and Bangkok: Local leaders use IQAir monitors to raise environmental awareness and guide safe outdoor activity.

These global contributors—and thousands more around the world—form the heart of the AirVisual network. Their commitment to transparency, awareness, and health creates a more informed and empowered world.

Turning Data Into Action: Tools for Learning and Impact

The goal isn’t just to publish accurate data—it’s to make that data meaningful and actionable for everyone. IQAir provides intuitive tools and resources to help individuals, schools, and communities interpret air quality trends and take steps toward cleaner air:

• The AirVisual App helps users compare local air to global benchmarks and receive real-time alerts.

• Custom dashboards for schools, clinics, and NGOs support public engagement and localized action.

• Educational collaborations with researchers bring data into classrooms, empowering students to explore air quality in hands-on ways.

• Community feedback tools within the platform allow contributors to flag anomalies and drive continuous improvement.

Democratizing air quality data helps turn awareness into advocacy—and science into better public health outcomes.

The takeaway

At IQAir, the integrity of AirVisual data is built on a foundation of scientific rigor, transparency, and an unwavering commitment to public health. Through meticulous sensor validation, continuous calibration, real-time data checks, and collaboration with the global air quality monitoring community, IQAir ensures that every piece of air quality data provided is accurate, reliable, and trustworthy. 

This approach to quality assurance reflects the company’s dedication to supporting informed decision-making and promoting healthier, cleaner environments worldwide.