How to use the map

How to use the map

Each hexagon represents an air quality sensor or a group of air quality sensors, depending on how closely you zoom. When you zoom out, the hexagon may contain many sensors. When you zoom in, the hexagon will represent one single sensor.

The hexagons represent the median of the current values of the sensors which are contained in the area (either one or many), according to the option selected (PM10, PM2.5, temperature, relative humidity, pressure, AQI). You can refer to the scale on the left side of the map.

The colurs indicate levels of air quality.

By clicking on a hexagon, you can display a list of all the corresponding sensors (either one or many) as a table. The first column lists the sensor-IDs. By clicking on the plus symbol next to a sensor ID, you can display two graphics: the individual measurements for the last 24 hours and the 24 hours floating mean for the last seven days. The values are refreshed every 5 minutes.

The Air Quality Index (AQI) is calculated according to the recommendations of the United States Environmental Protection Agency. Further information is available on the official page.(Link). Hover over the AQI scale to display the levels of health concern.

Check the air quality near you

What is particulate matter?

What is particulate matter?

The level of particulate matter in the air is a key indicator of air quality. 

What is PM, and how does it get into the air? Size comparisons for PM particles

PM stands for particulate matter (also called particle pollution): the term for a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.

Fine particles can come from various sources. They include power plants, motor vehicles, airplanes, residential wood burning, forest fires, agricultural burning, volcanic eruptions and dust storms. 

Studies have found a close link between exposure to fine particles and premature death from heart and lung disease. Fine particles are also known to trigger or worsen chronic disease such as asthma, heart attack, bronchitis and other respiratory problems. 

Particle pollution includes:

  • PM10 : inhalable particles, with diameters that are generally 10 micrometers and smaller; and
  • PM2.5 : fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.        
  • How small is 2.5 micrometers? Think about a single hair from your head. The average human hair is about 70 micrometers in diameter – making it 30 times larger than the largest fine particle.

The WHO guideline on air quality stipulates that PM2.5 not exceed 10 μg/m³ annual mean, or 25 μg/m³ 24-hour mean; and that PM10 not exceed 20 μg/m³ annual mean, or 50 μg/m³ 24-hour mean.


Get the apps!

We don’t yet have our own app, but we highly recommend downloading one or both of these. Both have unique features and allow you to track air quality in real time. Both are also available in English, though not yet in Catalan or Castellano. We hope to fix this soon.

Comes with widget


Special kids’ version


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