Smog covers buildings in New Delhi. (Agence France-Presse)
US today termed as "very unhealthy" the air quality level in the national capital, which could result in significant aggravation of heart or lung diseases.
The US Embassy in Delhi, which has recently established an air quality monitoring programme with on-site measuring instruments, said the Air Quality Index value 260 falls in the category of "very unhealthy".
The 260 AQI is a measure based on the amount of fine particulate or PM 2.5 in the air, a standard recognised by the US Environmental Protection Agency (EPA) and which allows the comparison against US standard measures.
The category defines "significant aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly, significant increase in respiratory effects in general population" as resultant health effects.
The US warning came with a cautionary statement that "people with heart or lung disease, older adults, and children should avoid all physical activity outdoors. Everyone else should avoid prolonged or heavy exertion."
The embassy further said that US EPA has developed a formula to convert raw PM 2.5 readings into an air quality index (AQI) value that can help inform health-related decisions.
However, when contacted, officials in the Earth Sciences Ministry said that the air quality level in Delhi during this time last year was even poorer.
They said that the average air quality at PM 2.5 today was bracketed in the poor category. They also forecast a "poor" quality level in the city in the next three days.