Air Quality Insights: Why AQ Readings Vary and How Ambee Bridges the Gap

Part 2: Why are AQ data readings sometimes different for the same location?

In June 2023, New York City saw an apocalyptic view as smoke from Canadian wildfires covered the city in smog. Once again, people were forced to mask up to protect themselves. If climate change continues, it may become the new normal.

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To understand the severity of the situation, people turn to their smart devices to check the ‘Air Quality Index,’ and having multiple AQIs for a single location might be confusing.

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Let’s understand why different sources may report varying air quality indices for the same area at the same time. But first,

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What tells us the quality of air we breathe?

Air quality is a growing concern worldwide, primarily due to significant impacts on public health. Air pollutants come from various sources, including natural and human factors - like wildfires and vehicular emissions. They have even infiltrated our offices and homes, making reliable air quality monitoring systems all the more crucial.

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Suggested Read: Indoor Vs Outdoor Air: Exploring the AQI divide

While some use air quality monitors equipped with sensors, others rely on remote sensing to assess the well-being of air - through a metric called Air Quality Index.

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You can think of AQI as a scale from 0 to 500, indicating the concentration of pollutants in the air - precisely, their density in a cubic meter of air. The greater the density of pollutants in the air, the higher the AQI.

Despite efforts to establish standards, challenges persist due to regional variations, different monitoring methods, and priorities.

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Let’s look deeper into why readings differ.

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1. Scales 

As different countries and organizations have taken note of poor air quality, they have their own methods and standards of calculation. For instance, Canada uses an 11-point scale, while the USEPA index runs from 0 to 500.

2. Data sources

When the Canadian wildfire incident caused concerns about air pollution in New York City - Two websites showed different air quality readings in the area. PurpleAir ranged from 43 to 349, while AirNow showed 159 to 188 in NYC. Why?

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PurpleAir data is more variable as it comes from low-cost sensors sold to the public. In contrast, Airnow data is collected from expensive reference-grade sensors.

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Ambee integrates data from over 60+ sources, from global monitoring stations to satellites, providing extensive geographical reach and ensuring the inclusion of local pollution sources.

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3. Pollutants

Air quality is an ever-changing story, influenced by various factors. As air masses move over the landscape - traffic patterns, local industry emissions and meteorological conditions like wind patterns impact air quality.

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During a dust storm in an area, PM10 levels in the air exceed expected levels. If a provider only reports on PM2.5 level, they might indicate good/moderate air quality in the area, which is not the case.

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Most local and state air quality forecasters report ozone and particle pollution.

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Ambee recognizes this limitation. We report six common pollutants (PM2.5, PM10, ground level O₃, NO₂, and CO), calibrate our data by combining satellite data with ground sensors, and account for neighborhood events.

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We don’t stop here. We use a multi-layer approach by integrating fire events, smoke plumes, and weather patterns for enhanced precision.

Each parameter has over 10 years of data to train the system. Multiple algorithms run throughout the ETL process to develop a superior air quality API.

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Further, Ambee’s sensors are designed to operate in harsh environments and are reliable enough to perform in city-level ambient conditions. These devices support multiple sensors to detect PM levels, CO₂ levels, and weather parameters. They transmit real-time emission data to the Ambee server via a 2G/LTE protocol.

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Refer to our air quality guide to discover more insights on air quality and outlier detection.

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4. Time period / Update frequency

If your provider reports air quality less frequently, disparities may arise.  It also varies by pollutant. The ozone AQI is an 8-hour index; for particle pollution, it’s 24 hours.

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At Ambee, we allow time for all our sources to run the entire pipeline and update our data 20 minutes past an hour UTC. This enables us to provide you with real-time, accurate air quality data.

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5. Resolution

Official stations are sparse and cannot monitor locations 5km away from the station. For example, AirNow reports the worst station reading in a location, which can be misleading for areas away from the pollution source

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You will find varying air quality reports for different geographic levels.

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Our models are customized for each location, providing more granular data. We provide data with a spatial resolution of up to 5 sq km at the postcode level, but we have the capability to go down further if required. This empowers our customers to understand the air quality around them at a street-level granularity.

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To put it simply, there is more to the air quality index than meets the eye. We use a hybrid model and ensure our data is properly calibrated to address all the dynamic factors affecting pollutant dispersion in the atmosphere. Ambee’s commitment to actionable data provides a more accurate reflection of the air you breathe.

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Why Ambee?

Ambee's calibrated and linearized sensors offer long-term stability, a reference channel, and encrypted IoT connectivity for reliable, large-scale monitoring and data acquisition.

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Our advanced algorithms enable accurate and hyperlocal air quality insights for healthier environments. Read our first blog in the series to learn about our meticulous process from data collection to delivery.

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Stay tuned for the final blog, where we answer - “Why should you trust us?”

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Interested in Ambee’s AQ? Get in touch with us today!