According to the advisory, while the city with high volume of pollutants in the air is bad for exercising, running or participating in a marathon can add at least two tablespoonfuls of toxic ash to the lungs.
Wednesday saw a further fall in Delhi's air, with Air Quality Index (AQI) ranging from 440 to 400 considered "severe" being recorded at different locations including R.K Puram and Siri Fort in South Delhi, Delhi Technical University (DTU) in North Delhi, ITO in Central Delhi, Anand Vihar in Northeast Delhi and Punjabi Bagh in West Delhi.
The data was based on the readings of monitoring stations of Central Pollution Control Board (CPCB).
All other regions in Delhi and NCR recorded either "severe" or "very poor" air quality, with PM2.5, or particles with diameter less than 2.5mm, acting as the major pollutant.
"Running a marathon in these air conditions can deposit approximately two tablespoonfuls of toxic ash in your lungs," the advisory stated, adding that it was vital to plan exercise environment very carefully.
The PM2.5 value of 10 monitoring stations of the System of Air Quality and Weather Forecasting and Research (SAFAR) was found ranging between 392 and 326 units against the permissible limit of 60 units as per national standards and 25 units as per international standards.
"The current level of air pollution in Delhi affects even the unborn child in mother's womb," advisory added.
The advisory points out that while a normal adult breathes approximately six litres of air per minute at rest, during exercising it increases to 20 liters. With current air-pollution in Delhi and NCR, this increases toxins in lungs.
"Exercising is vital for health but not when we are breathing poison."
The advisory endorsed by seven medical practitioners, including those from the Department of Respiratory Medicine and Chest Surgery of Sir Ganga Ram Hospital states that even N-95 standard masks, which stops fine particles, "could be suffocating while exercising".
"Exercise areas should be at least 200 meters away from roads, construction sites and smoke-emitting industry," advisory says, adding that "even this does not guarantee clean air".