Every year, like clockwork, Delhi chokes.
A thick, toxic haze settles over the city - stinging eyes, burning throats and sending air quality monitors into panic mode.
For the past few days, the air in Delhi and its neighbouring satellite cities has hovered between the "poor" and "very poor" categories.
It worsened sharply after Diwali, one of India's biggest festivals, as fireworks lit up the night sky and filled the air with smoke. Headlines reported that it was the worst post-Diwali air quality the city had experienced in the past four years.
With that, the city once again found itself confronting its annual, predictable - yet avoidable - crisis: air pollution.
