Mercer’s overall ranking for quality of living has revealed that Zurich again ranks as the world’s top city, with a rating of 108.1. The city narrowly out-ranks Geneva, which scores 108. Vancouver and Vienna follow in joint third place and score 107.7. However, the 2007 Worldwide Quality of Living Survey by Mercer Human Resource Consulting has found that four of the world’s five top-scoring cities for health and sanitation are in North America. Calgary ranks top with a score of 131.7, followed by Honolulu, which scores 130.3. Ottawa and Minneapolis take fourth and fifth places with scores of 127.2 and 125.7 respectively. Montreal and Vancouver both rank in 10th place (score 123.7). Toronto is at position 21 with a rating of 122.4. Scores are based on the quality and availability of hospital and medical supplies and levels of air pollution and infectious diseases. The efficiency of waste removal and sewage systems, water potability and the presence of harmful animals and insects are also taken into account. Cities are ranked against New York as the base city which has an index score of 100. The analysis is part of Mercer’s Worldwide Quality of Living Survey, covering 215 cities, which is conducted to help governments and major companies to place employees on international assignments. The analysis is based on an evaluation of 39 quality of living criteria for each city including political, social, economic and environmental factors, personal safety and health, education, transport and other public services.