Cameron: “extraordinary” pollution levels reached in UK

The UK has seen a significant rise in emergency calls as high levels of air pollution continue to affect large areas.

London Ambulance Service reported a 14 per cent rise in 999 calls related to breathing difficulties on Wednesday.

Prime Minister David Cameron described the pollution as "extraordinary" and urged people to seek advice from the Met Office and Public Health England.

Air quality data from the Department for Environment, Food & Rural Affairs (Defra) shows London and the South East experiencing pollution on Thursday at the maximum level of 10.

Cameron admitted the capital's atmosphere was "unpleasant" and health warnings have been issued for people with lung and heart conditions.

Levels in eastern England have reached nine with north-west England, Yorkshire and Humberside, the Midlands and south Wales also affected.

The smog-like conditions are expected to clear by Friday and have been caused by a combination of local and continental pollution, and dust from the Sahara.

The London Ambulance Service reported that it had received 227 emergency calls for patients with breathing problems on Wednesday which was up from a daily average of 200.

Defra uses a 10-point scale for measuring air quality - with level one signifying a "low" risk of air pollution and 10 for "very high" levels.

According to Defra, levels in eastern England reached level nine by Thursday morning with “moderate" levels expected in parts of Northern Ireland and "many other parts of England and Wales" throughout the day.

Levels were recorded at eight on Wednesday in parts of south-east England and East Anglia, with level seven in Greater London.

Levels are determined by the concentration of five pollutants in the air - ozone, sulphur dioxide (SO2), nitrogen dioxide (NO2) and two types of particulate matter.

In February, the European Commission began legal action against the UK for failing to reduce levels of NO2 air pollution.