London, Jan 26 (IANS): In 2019, around 4,000 deaths in London could be attributed to air pollution, with the highest number of fatalities recorded in the city's outer boroughs, according to a new study.

"This calculation is for deaths from all causes including respiratory, lung cancer and cardiovascular deaths," Xinhua news agency quoted the study published on Monday by researchers from the Imperial College London.

Commissioned by the Transport for London and the Greater London Authority, researchers from the Imperial's School of Public Health's Environmental Research Group found that "if London is enabled to meet the WHO (World Health Organization) guideline for PM2.5 by 2030, the population in London would gain a 20 per cent increase in life years saved over the next 20 years".

The researchers predicted in the report that London specific air quality policies, alongside wider improvements in air quality, "will increase the average life expectancy of a child born in London in 2013 by six months, compared with 2013 concentrations remaining unchanged".

Calling the report as "a stark reminder", London Mayor Sadiq Khan said air pollution in the city still represents a public health crisis and urgent action is needed.

According to a City Hall spokesperson, 99 per cent of London does not meet WHO recommended limits for PM2.5.

The PM2.5 reading is a gauge monitoring airborne particles of 2.5 microns or less in diameter, which can penetrate deep into people's lungs.

The air pollutant is a concern for people's health when levels in air are high.