The activity sectors of energy production and industrial
combustion (SNAP 1 and 3) are the ones that most contribute to
SO2 emissions, giving also an important contribution to NOX
emissions. Nevertheless, the transport sector (SNAP 7) is the main
responsible for NOX total emissions in Portugal. Domestic and
industrial combustion and processes (SNAP 2, 3 and 4) emit mainly
NMVOC, PM2.5 and PM10. For NMVOC, the major emission source is
the use of solvents (SNAP 6).