Environment
Air pollution varies across London:

Concentration of nitrogen oxides: selected areas, 2004

These oxides are produced during combustion. They are believed to aggravate asthmatic conditions, and are involved in tropospheric production of ozone. They eventually form nitric acid when dissolved in atmospheric moisture, forming a component of acid rain.

Forty-two per cent of all Middle Layer Super Output Areas (MSOAs) in London have the highest emission intensity scores for nitrogen oxides. This compares with just 6 per cent of MSOAs in the North East and 9 per cent in Yorkshire and The Humber.

Heathrow airport has particularly high concentrations of four air pollutants: nitrogen oxides, particulate matter, sulphur dioxide and benzene. London also has pockets of green space, such as Richmond Park and Epping Forest, which have lower concentrations of emissions.

Sources of air pollution include car and diesel fumes. These accounted for 40 per cent of emissions of nitrogen oxides and nearly 70 per cent of fine particulates in London in 2003. Gas consumption and gas leakage are also major sources of oxides of nitrogen in Inner London, together contributing about 50 per cent of these emissions in 2003.

The chemical quality of London's rivers and canals has improved since 1990. In 2005, 78 per cent were graded 'fair' or 'better' compared with 71 per cent in 1990. However, this is still low compared with the average of 93 per cent for all rivers and canals in England.

Water consumption in unmetered households supplied by Thames Water (which covers most of the London area) has grown from 164 litres per head per day in 2003/04 to 167 litres per head per day in 2005/06. In contrast, consumption in metered households has remained at 154 litres per head.

Eighty-eight per cent of estimated abstractions from surface and groundwaters in the London area are used for public water supply. This compares with just 45 per cent across England and Wales in 2004.

An average London household produces 20.5kg of household waste per week compared with the average for England of 23.2kg. In 2005/06 London recycled 21 per cent of household waste, up from 11 per cent in 2002/03. In England the average was 27 per cent.

Forty-four per cent of land turned over to residential use in London during 2002 to 2005 was vacant land that had previously been developed. Redevelopment of existing residential land increased to 27 per cent compared with 17 per cent in 1995 to 1998.