Overall, air quality has improved significantly in the UK, US and Canada since precise measurements began in the mid 1970s. In part, this is a result of regulatory restrictions on emissions. However, to a considerable extent the decline in emissions of PM10s and Nitrogen Dioxide has been a consequence of profit-driven technological developments. These more efficient engines burn more of the fuel they consume and consequently emit fewer waste gases. The lack of significant decline in VOC emissions in the UK is in part a consequence of the fact that VOCs are produced naturally by trees - so policies that have increased the number of trees have inadvertently increased VOC emissions.
Water availability is the total amount of freshwater water in the system.
Water use is the amount of this freshwater that is used for human purposes. No comparable measures were available for the US and Canada. Biological water quality. Over 90 per cent of rivers and canals are classified as being in 'fair' or 'good' condition by the Environment Agency. An assessment of the quality of water based on various chemical and biochemical measures.