PM10 and PM2.5 data from the NAQIS are divided into two groups (SINCA, 2015): preliminary data and official data. Preliminary monitoring data correspond to two categories of data: data that AT13148 have not been validated operationally and were received online automatically and data that have been validated operationally through a validation process performed by the station operator or measurement network. The preliminary data that have not been validated cannot be used to officially verify compliance with the current legislation. The official monitoring data correspond to data previously validated by operators and ratified by the competent authority. For PM10, 72.5% of private monitoring stations (92 stations) send preliminary data, 51.2% (65 stations) send preliminary data that has been validated operationally and 0% (0 stations) send official data. For PM2.5, only 10.3% of the stations (12 stations) send preliminary data and 0% (0 stations) send official data. Although the percentage of official data is low, stomach is common practice to use all data sent to the public NAQIS networks to assess air quality standards and implement exceptional measures to protect the public health, such as restrictions on industrial operations, limits on automobile use and bans on firewood combustion. The lack of official data highlights the existence of deficiencies in the systematization of the information, the validation methods, the assurance procedures and the quality control of the information.