Chennai is the capital of the Indian state of Tamil Nadu. Located on the Coromandel Coast off the Bay of Bengal, it is one of the biggest cultural, economic and educational centres in South India. According to the 2011 Indian census, it is the fourth-largest city and fourth-most populous urban agglomeration in India. The city together with the adjoining regions constitute the Chennai Metropolitan Area, which is the 36th-largest urban area by population in the world. Chennai is one of the Indian cities most visited by foreign tourists, and is the 47th most visited city in the world. The Quality of Living Survey rated Chennai as the safest city in India. Chennai attracts 45 percent of health tourists visiting India, and 30 to 40 percent of domestic health tourists. As such, it is termed "India's health capital". As a growing metropolitan city in a developing country, Chennai confronts substantial pollution and other logistical and socio-economic problems.