As many Indian cities battle air pollution, officials at the country's top medical institute AIIMS said poor air quality has increased the number of patients visiting hospitals with respiratory problems. All India Institute Of Medical Sciences (AIIMS) Director Dr Randeep Guleria said there has been an increase in the number of patients visiting hospitals with complaints of respiratory problems and after suffering cardiac arrests during the months when pollution levels are high. Studies are being conducted to asses the impact of pollution on public health, he told reporters at the sidelines of an event at the AIIMS here. Delhi's air quality remained in the 'severe' category for the fourth consecutive day Tuesday as meteorological conditions continued to be unfavourable for dispersion of pollutants. Also read|\u00a0Delhi Weather: Fog disrupts air, rail traffic; air quality \u2018severe\u2019 The city is facing its worst pollution crisis since Diwali. While the Central Pollution Control Board (CPCB) data showed the overall air quality index (AQI) at 'severe' level of 416, the Centre-run System of Air Quality and Weather Forecasting (SAFAR) recorded an AQI of 423. While, the national capital has been battling air pollution for quite a few years now, air quality in Kolkata has dropped significantly over the last few months and in November it was the most polluted city in India. Guleria asked people to avoid visiting most polluted areas and taking preventive measures. Meanwhile, Finance Minister Arun Jaitley and Health Minister J P Nadda Tuesday inaugurated water cooler facilities in AIIMS, donated by the Girdhari Lal Memorial Trust.