On Wednesday, the US embassy's website calculated Delhi's air quality index (AQI) at 248 at 8 am and 260 at 6 pm. The index is a measure of air quality on a progressively deteriorating scale of 0 to 500, based on fine particulate matter (PM2.5) in the air.
The embassy releases hourly AQI figures.
Readings in the range of 201-300 are termed 'very unhealthy' as per US health standards. These readings have prompted an international web portal warn against letting kids out for prolonged periods.
Air quality in the national capital deteriorated alarmingly a day after Diwali, SAFAR claimed last week.
The Respirable Suspended Particulate Matter (RSPM), which directly affects breathing, had gone up by five times from the national ambiance air quality standard.
"These pollutants can harm the heart and brain as well. People with existing heart or lung diseases such as asthma, chronic obstructive pulmonary disease, congestive heart disease, or ischemic heart disease are at increased risk of admission to hospitals based on the severity of already existing problem," senior scientist Dr Gufran Beig at SAFAR had said, last week.