on emissions and maintaining water quality. Since 1995, there have been significant developments in the analysis of air pollution in the Sydney metropolitan region. The development led to the release of the Metropolitan Air Quality Scheme (MAQS), which led to a broader understanding of the causation of pollution in Sydney, allowing the government to form appropriate responses to the pollution. The 2019–20 Australian bushfire season significantly impacted outer Sydney, and consequently dramatically reduced the air quality of the Sydney metropolitan area leading to a smoky haze that lingered for many days throughout December. The air quality was 11 times the hazardous level in some days, even making it worse than New Delhi's, where it was also compared to "smoking 32 cigarettes" by Associate Professor Brian Oliver, a respiratory diseases scientist at the University of Technology Sydney. Australian cities are some of the most car-dependent cities in the world, especially by world city standards, although Sydney's is the lowest of Australia's major cities at 66%. Furthermore, the city also has the highest usage of public transport in an Australian city, at 27%–making it comparable with New York City, Shanghai and Berlin. Despite its high ranking for an Australian city, Sydney has a low level of mass-transit services, with a historically low-density layout and significant urban sprawl, thus increasing the likelihood of car dependency. Strategies have been implemented to reduce private vehicle pollution by encouraging mass and public transit, initiating the development of high density housing and introducing a fleet of 10 new Nissan LEAF electric cars, the largest order of the pollution-free vehicle in Australia. Electric cars do not produce carbon monoxide and nitrous oxide, gases which contribute to climate change. Cycling trips have increased by 113% across Sydney's inner-city since March 2010, with about 2,000 bikes passing through top peak-hour intersections on an average weekday. Transport developments in the north-west and east of the city have been designed to encourage the use of Sydney's expanding public transportation system. The City of Sydney became the first council in Australia to achieve formal certification as carbon-neutral in 2008. The city has reduced its 2007 carbon emissions by 6% and since 2006 has reduced carbon emissions from city buildings by up to 20%. The City of Sydney introduced a Sustainable Sydney 2030 program, with various targets planned and a comprehensive guide on how to reduce energy in homes and offices within Sydney by