air pollution 346 air cleanness monitoring 83 environment protection 43 health harmful substances 36 imissions 29 issues 28 contaminants 27 more ... environmental pollution 21 atmosphere (biology) 19 aerosols 18 environment 18 environmental hygiene 17 atmosphere (geophysics) 16 measurement 15 dust particles 15 combustion 15 climatic changes 14 internal climate 12 exhaust gases 11 water pollution 11 industrial air conditioning 10 air cleaners 10 anthropogenic contamination of atmosphere 9 aromatic polycyclic hydrocarbons 9 Earth warming 9 internal combustion motors 9 biofuels 8 mathematical models 8 towns 8 carbon dioxide 8 less ...