INDOOR AIR QUALITY
The European Union and the American Environmental Protection Agency (EPA) conducted a study on the air quality values and norms of the air we breathe indoors and published the table below.
The table is based on PM 2.5 figures because these are inhaleable particles with diameters 2.5 micrometer or smaller. These fine particles pose greater risk to health. The table below defines the air quality as defined by EPA.