Pollution general:

 Air pollution emission database EMEP
Database of officially reported emissions by country and year.

Indoor pollution

 Indoor pollution global
Extensive overview (scientific summary paper) of estimated burdens through indoor air pollution world wide, with graphs and tables.

 Indoor air pollution, energy and health
Report of the World Health Organisation on the relation of indoor air pollution, energy and health with a focus on developing countries.

Nitrogen oxides

 Modeling lightning and ozone formation
Scientific paper introducing the relation of lightning, nitrogen oxides and ozone formation and showing modelled maps of the global distribution. (NASA)

Ozone

... see separate link list

Nitrous oxide

 N2O from European forest soils
Scientific article about nitrous oxide emitted at different measurement points in Europe from the forest soil.

Carbon monoxide

... see separate link list

Heavy metals

 European Assessment reports
Report on European heavy metals, text only, technical paper of the EC, 2000

 Poisoning symptoms and treatment
Detailed explanation of poising symptoms of severa heavy metals and treatment in particular by chelating.