Why Air Quality Maps Have Different Data

Real-time Air Quality Map

Air quality maps are an excellent source to evaluate the air around you. But some maps show different information than others. This makes it confusing, especially when the results are polar opposites—one may say that your air is safe, while another says it’s harmful. 

So, how can you check the air pollution around you when you’re unsure of which map to trust? 

Below, we’ll explain why different air quality maps may show different data below. By understanding how these maps work, you’ll know what air quality map to trust. 

How Do Air Quality Maps Work? 

Air quality monitors work by detecting air pollutants through sensing mechanisms. The data is then processed, transmitted, and integrated into air quality maps, where it’s visually represented to help people assess and respond to air quality conditions.  

Here’s how air quality data is gathered and shown: 

  1. Detecting Pollution: Air quality monitors will use either chemical, optical, or gas sensors to detect, quantify, and measure pollutants in the air.  

  2. Data Processing: Once the monitors measure pollutants, the collected data is processed and converted into readable, accurate values.  

  3. Transmission: Air quality monitors are often part of a network. They send their data to a central database or monitoring station through wired or wireless communication channels. 

  4. Integration with Maps: The data collected by these air quality monitors is often integrated into air quality maps with color-coded scales and real-time updates.  

While air quality maps generally work similarly, the biggest difference is how they present the data. If you see significant discrepancies, it may be because the maps are using different air quality indexes.

What are the AQI in Different Countries? 

Air Quality Index (AQI) scales are systems used to communicate local air quality. These scales help you assess air pollution levels and potential health risks, especially during dust storms and wildfires

While international AQI scales are used globally, they can differ from one country to another.  

For example, the United States AQI scale measures ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. It uses a color-coded scale with values ranging from 0 to 500, where lower values indicate better air quality.  

In comparison, China’s and India’s AQI scales have different pollutant-specific breakpoints. They also have very different calculation methods when measuring the different air pollutants. One instance is how Australia’s AQI scale only goes up to 200 (where any result above 200 is considered “hazardous”), but India’s AQI scale goes up to 500, and the air isn’t considered “severe” until it surpasses 401.  

Here is a comparison for you to see the significant differences from one AQI to another: 

Comparison of different AQI scales in several countries

Each country tailors its AQI scale to its environment and health standards. While the air pollutants measured are similar, the thresholds and results may differ. That said, you must be familiar with your local AQI scale to understand air quality levels accurately. 

Why are Air Quality Maps Different from Each Other? 

Air quality maps can vary in terms of what data they use, and where they get that data. Aside from AQI differences, here are some other key factors for why maps may differ from each other: 

  • Data Sources: Different data sources can impact the quality and accuracy of the map. Maps may use data from government agencies, research institutions, and commercial air quality monitors or any combination of these. Moreover, the location of these air quality monitors can also affect the data. 

  • Pollutants Measured: Some maps emphasize particulate matter (PM2.5 and PM10), while others may prioritize gases like ozone, carbon monoxide, sulfur dioxide, or nitrogen dioxide. The choice of air pollutants affects the map's relevance to health and environmental concerns. 

  • Measurement Methods: Some maps may rely on high-precision instruments with established accuracy standards, such as Federal Equivalent Method (FEM) or Federal Reference Method (FRM) devices. While others may use sensors like PurpleAir air quality monitors.

Because of these differences, you’ll want to use an air quality map that uses trusted data sources, identifies the pollutants you want to know, and measures pollutants accurately. 

So, Which Air Quality Map is Best? 

With many air quality maps available, it may be difficult to choose which one to trust. Our advice is to stick to a map that is reliable and easily understandable. For example, our PurpleAir Map is widely used due to several reasons: 

  • Dense Air Quality Network: The PurpleAir Map incorporates data from a vast network of air quality monitors placed in various locations. This dense air quality monitor network provides detailed and updated information about air quality in communities worldwide. 

  • Accurate Data: The PurpleAir Map pulls data from PurpleAir monitors. These devices have been proven to be precise, even when compared against professional-standard Federal Equivalent Methods (FEM) and Federal Reference Methods (FRM) monitors—the gold standard in air quality.  

  • Real-Time Updates: PurpleAir air quality monitors continuously collect data, and this information is available on the map. You can track air quality conditions throughout the day, as the map is updated every two minutes, which is faster than government maps that update every few hours.

  • Notable Users: PurpleAir's data is trusted and used by reputable organizations, including NASA, South Coast AQMD, ExactAQ, Google, and more. This demonstrates its credibility and wide acceptance within the air quality monitoring community. 

  • Detailed Filters: You can adjust data layers to see specific data on the PurpleAir Map. You can also choose different AQI scales, apply conversion factors, choose a time period, know the air quality monitor locations (indoors or outdoors), save your settings, and more. 

The PurpleAir Map is one of the most trustworthy options available to get accurate air quality data. For more help, we have a guide to using PurpleAir Map

Worried About Air Quality? 

Monitor the Particulate Matter levels around the world with our free, real-time PurpleAir Map, or join PurpleAir’s mission to make air quality data accessible to everyone by investing in an air quality monitor for your home. Together, we can be informed and make changes in our daily habits and the community to improve air quality.