As India’s capital Delhi fights toxic smog that has blanketed the city for more than a week, Chief Minister Arvind Kejriwal announced the closure of all schools.

Mr Kejriwal said: “Schools are being shut so that children don’t have to breathe polluted air.”

On Saturday particulate matter 2.5 (PM2.5) levels reached 319 on the air quality index.

That compares to the up to 82 in London, according to the Real-time Air Quality Index.

The size of these particles means that can travel into organs that help respiration, including the nose and throat and enter the bloodstream.

The level of air pollutants is more than 20 times the maximum daily limit recommended by the World Health Organization.

As of Monday 15th November, the Central Pollution Control Board (CPCB), the organisation under the Ministry of Environment, Forest and Climate Change, classified Delhi’s air quality as being ‘very poor’ with an index value of 353 for PM2.5.

The CPCB also added that of 136 cities in the country 27 cities remain in the category ‘very poor’ and 40 cities in the category ‘poor’.