Columbia subject headings:
Air quality management--OECD countries.
Air--Pollution--OECD countries.
Hazardous substances--Environmental aspects--OECD countries.
Harvard subject headings:
Air quality management
Air quality management--European Economic Community countries.
Air--Pollution
Air--Pollution--European Economic Community countries.
Hazardous substances--Environmental aspects--European Economic Community countries.
Hazardous substances--Environmental aspects.
Princeton subject headings:
Air quality management--European Economic Community countries.
Air--Pollution--European Economic Community countries.
Hazardous substances--Environmental aspects--European Economic Community countries.