Air pollution in Delhi continued to worsen, causing serious health concerns among residents even as weather officials warned of further worsening of air quality in the coming days. On 5 November, the levels of particulate matter PM10 and PM2.5 in the National Capital spiked to ‘hazardous’, leaving Delhiites gasping for breath. Particulate matter is a complex mixture that may contain soot, smoke, metals, nitrates, sulfates, dust, water and tire rubber. Fine particulate matter, also known as PM2.5, can enter the lungs and bloodstream.