system to filter airborne particles. An abrasive blasting was used, with the lead waste collected and safely removed from the site for disposal. Between December 2006 and March 2010 the bridge was subject to works designed to ensure its longevity. The work included some strengthening. Since 2013, two grit-blasting robots specially developed with the University of Technology, Sydney have been employed to help with the paint stripping operation on the bridge. The robots, nicknamed Rosie and Sandy, are intended to reduce workers' potential exposure to dangerous lead paint and asbestos and the blasting equipment which has enough force to cut through clothes and skin. Tourism South-east pylon Even during its construction, the bridge was such a prominent feature of Sydney that it would attract tourist interest. One of the ongoing tourist attractions of the bridge has been the south-east pylon, which is accessed via the pedestrian walkway across the bridge, and then a climb to the top of the pylon of about 200 steps. Not long after the bridge's opening, commencing in 1934, Archer Whitford first converted this pylon into a tourist destination. He installed a number of attractions, including a café, a camera obscura, an Aboriginal museum, a "Mother's Nook" where visitors could write letters, and a "pashometer". The main attraction was the viewing platform, where "charming attendants" assisted visitors to use the telescopes available, and a copper cladding (still present) over the granite guard rails identified the suburbs and landmarks of Sydney at the time. The outbreak of World War II in 1939 saw tourist activities on the bridge cease, as the military took over the four pylons and modified them to include parapets and anti-aircraft guns. In 1948, Yvonne Rentoul opened the "All Australian Exhibition" in the pylon. This contained dioramas, and displays about Australian perspectives on subjects such as farming, sport, transport, mining, and the armed forces. An orientation table was installed at the viewing platform, along with a wall guide and binoculars. The owner kept several white cats in a rooftop cattery, which also served as an attraction, and there was a souvenir shop and postal outlet. Rentoul's lease expired in 1971, and the pylon and its lookout remained closed to the public for over a decade. The pylon was reopened in 1982, with a new exhibition celebrating the bridge's 50th anniversary. In 1987 a "Bicentennial Exhibition" was opened to mark the 200th anniversary of