Helena, Montana 1869, October 1871, August 1872 and January 1874 that swept through the early mining camp. On August 2, 2016 an arson attack severely damaged the "tower" and was deemed structurally unstable. The tower is to be "demolished"; however, it is to be ""rebuilt" using the same methods that were used in its original construction. In 1889, railroad magnate Charles Arthur Broadwater opened his Hotel Broadwater and Natatorium west of Helena. The Natatorium was home to the world's first indoor swimming pool. Damaged in the earthquake of 1935, it was closed in 1941. The many buildings on the property were demolished
Indoor air quality ventilation. Instead of setting throughput at a fixed air replacement rate, carbon dioxide sensors are used to control the rate dynamically, based on the emissions of actual building occupants. For the past several years, there have been many debates among indoor air quality specialists about the proper definition of indoor air quality and specifically what constitutes "acceptable" indoor air quality. One way of quantitatively ensuring the health of indoor air is by the frequency of effective turnover of interior air by replacement with outside air. In the UK, for example, classrooms are required to have 2.5 outdoor air changes per