The relationship between wealth (or poverty) and environmental degradation varies with each factor analysed. For instance, emissions of carbon dioxide increase with wealth. Emissions of sulphur dioxide also increase with industrialisation, but diminish when a country becomes richer and filters are installed in power stations or metal smelters. As for water quality, it is lower in poor countries and increases with wealth, but the consumption of water also increases with wealth; hence water reserves are overexploited in some rich countries and suffer salinisation in coastal areas. Finally, the production of domestic wastes increases as living standards increase, and their composition makes them harder to recycle.