The layer of smog lingering over Delhi thickened on Tuesday, lowering visibility and smudging landmarks from view, as the air quality turned ‘severe’ amid calmer winds and raging farm fires in Punjab.

NASA’s satellite images showed a dense cluster of red dots denoting farm fires in Punjab and parts of Haryana, and a layer of smoke blanketing huge swathes of the Indo-Gangetic plains from east Pakistan to east Uttar Pradesh.

Delhi’s air quality index (AQI) stood at 429 at 10 am on Tuesday, worsening from 352 at 4 pm on Monday. An AQI above 400 is considered “severe” and can affect healthy people and seriously impact those with existing illnesses.

According to the Energy Policy Institute at the University of Chicago (EPIC)’s Air Quality Life Index (AQLI) released in June, residents of Delhi stand to lose 10 years of life expectancy due to poor air quality.