Frequently Asked Questions

What is monitoring station data?

Monitoring station data are values measured at different on-ground monitoring stations. These stations mainly monitor PM2.5 concentration in the air and send data back to data centers operated by various organizations.

From where is the monitoring station data collected?

The monitoring station data is collected from 3 main sources:

• The Northern Center for Environmental Monitoring network
• The Hanoi Environment Protection Agency network
• The stations operated by the Embassy and Consulate General of America

What characteristics does the satellite AQI data have and how is it processed?

The satellite AQI data is the map data of the PM2.5 concentration distribution over the Vietnam region. Each pixel contains the PM2.5 value that represents a 3x3km space in real life. Daily estimations of PM2.5 concentration are made using the Mixed Effect Model and various input data such as: monitoring station data, Aerosol Optical Depth (AOD) products from the MODIS Terra/Aqua and VIIRS NPP satellites, meteorological (mainly humidity) map data, planetary boundary layer height data, and land use data (normalized difference vegetation index, road density maps).

How frequent are different types of data updated?

• The monitoring station data is updated hourly
• The satellite AQI data is updated daily
• The meteorological data (WRF-Chem) is updated hourly