The main pollutants of outdoor air quality are:
- Nitrogen oxides: road traffic
- Pollutant ozone: generated from road traffic under certain atmospheric conditions
- Particulate matter: road traffic, residential heating, agricultural activity but also from natural sources (desert dust, fires, volcanoes, skimmings…); These are the pollutants taken into account in AQMO.
- Heavy metals: industry + carbon combustion.
- PAH (Polycyclic Aromatic Hydrocarbons): carbon combustion (wood, coal, hydrocarbons)
- VOC (Volatile Organic Compounds): fuels, paints, solvents, adhesives, …
- Carbon monoxide: carbon combustion
Particulate Matter Measurement
PM stands for Particulate Matter and 2.5 for the diameter, being less than 2.5m (diameter of a hair: 50 to 100m).
- Natural (soil erosion, pollens, Saharan dust, forest fires, sea salt spray…)
- Or anthropogenic (carbon combustion, road transport, agricultural and industrial activity)
Effects on Health
There are varied effects that depend on the size and chemical composition of the particles. The smaller these particles are, the deeper they penetrate the respiratory system (lungs or blood system). PM have health effects on the respiratory, neurological, cardiovascular and hormonal systems. PM2.5 are considered carcinogenic.
Effects on Environment
PMs affect climate, photosynthesis, impaired visibility and building decay (especially historical).
The calibrated and controlled instruments of Air Breizh make it possible to measure concentrations (amount of pollutant in a volume of air at a given moment or over a given period).
For each pollutant, these figures are evaluated on their level over time: this makes it possible to identify if thresholds are reached or exceeded. When this occurs, Air Breizh issues an alert to warn the population of a pollution episode (recommendation to populations).
These concentrations also allow for each measured pollutant to identify a level (called pollutant index) used as a “sub-index” for the calculation of a global air quality index:
- 3 pollutants define the index: fine particles (PM 10); nitrogen dioxide (NO2) and ozone (O3)
- The index determined goes from 1 to 10:
- 1 to 4 Very Good to Good
- 5-7 Medium to Mediocre
- 8 to 10 Bad to Very bad
Air Breizh relies on the forecast of this index for the day and the next day to issue a daily report of air quality across the region.