From January 1, 2021, a new air quality index comes into effect. Now, particles that are particularly hazardous to health such as fine PM2.5 particles will be taken into account when checking the air quality. This decision was made because the experts realized that these molecules smaller than 2.5 micrometers, are able to lodge deep in the respiratory functions of living beings. The bodies in charge of monitoring air quality have announced that the particles which will henceforth be measured are nitrogen dioxide (NO2), fine particles PM10, fine particles PM2.5, sulfur dioxide ( SO2) and ozone (O3). The introduction of PM2.5 particles resulted in the appearance of the color purple in the color chart that already exists.

Air quality indices

The air quality is rated from 1 to 10 (from “very bad” to “very good”). We also use colors (light blue, green, yellow, red, dark red) to make the classification. Lately, purple representing the “extremely bad” class has been added to this palette. The “very good” category has been removed. As of January 1, 2021, we will use more than the six levels, not quantified (good, average, degraded, bad, very bad and extremely bad). Colorful emoticons are used to represent them. Every day, experts calculate the ATMO index based on the concentrations of 5 regulated pollutants: fine particles whose diameter is less than 2.5 micrometers (PM2.5), fine particles whose diameter is less than 10 micrometers ( PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3). To find the air quality index for your region, you just need to visit the Atmosud website.

What impact will the new index have?

The inclusion of fine particulate matter PM2.5 in the list of regulated pollutants helps to better describe air quality. The thresholds for NO2 and ozone have been lowered. These latest measures taken will lead to a significant increase in the number of bad days. The prefectural systems and the thresholds for the PM2.5 fine particle index are not entirely consistent. We will therefore probably see bad days without triggering a prefectural system.

Why is the ATMO index changing?

Air quality is a concern of many citizens. The ATMO index is regularly updated to meet the expectations of the populations. Thus, each year, the experts take into account developments in forecasting and measurement of air quality. This constant constant allows us to always be in phase with the thresholds of the European index. The ATMO index is also evolving to be able to follow the recommendations of the World Health Organization. The main goal of these changes is to keep everyone healthy.


Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.