Data indicates that stubble burning's contribution to Delhi's PM2.5 levels this winter was limited, accounting for approximately 3.5% between October and December, a decrease from previous years. Despite this, Delhi's air quality worsened in December after the farm fire season concluded, with PM2.5 levels increasing by 29%. This suggests other factors significantly impact pollution levels, as air quality deteriorated even when stubble burning's contribution dropped to about 0.2%.