A thick haze was visible across the city from Tuesday and some government pollution monitors have recorded concentrations of 999 – the highest they can measure – as dust storms kicked up in nearby Rajasthan state blanketed the region.

river of dust, high atmospheric aerosol loading, and hazardous air quality over N.I. subcontinent, as seen today by @nasa satellites and forecast at https://t.co/wBpx9GB1Cn – data from @NASAEarthData #worldview @airqualityindia @PakAirQuality @Open_AQ @jksmith34 @CBhattacharji pic.twitter.com/KnE25oTBJs

— NGEL (@nexgenearth) June 14, 2018

Though the billowing clouds of dust and sand were blamed for the immediate spike in pollution levels, the sight of dense smog engulfing Delhi months before winter has underscored a growing awareness that harmful air is a year-round problem for the city (via).