Environmental issues such as poor air quality and water pollution have turned away inbound tourists during the first quarter of the year, according to the Chinese tourism authority.

The number of overseas tourists to China was estimated at 31.66 million in the first three months, a drop of 1.8 percent compared with the same period last year, according to a report released on Tuesday by the China Tourism Academy, affiliated with China National Tourism Administration.

Chen Xu, a researcher from the academy, added that the revenue brought by overseas tourists was about $11.3 billion, a 3 percent drop from last year.

The data were calculated based on the figures from January and February as well as historical data from past years, Chen said. The actual figures from March will not be available till late this month.

The report was based on the national tourist satisfaction survey the academy conducted. The academy started the quarterly survey during the second quarter of 2009.

The survey is based on a questionnaire, online comments from tourists as well as complaints in the surveyed cities, Chen said.

The tourist satisfaction index for the first quarter in 2013 stood at 77.62, according to the report. The full score is 100,

Though a score above 75 means "basically satisfactory", the score for the first quarter dropped by 5.83 compared with the same period in 2012 and 9.16 compared with the fourth quarter in 2012, the report said.

Suzhou, Huangshan and Chengdu were the top three cities in terms of tourist satisfaction among the 60 cities surveyed in China, with Suzhou, Jiangsu province, receiving the highest score of 85.47, the report said.

The researchers also conducted undercover investigations for the survey, Chen said.