In the two decades prior to the 1979 revolution, natural gas became the fuel of Iran’s future. During that time, gas ceased to be a waste product burned in the fields. Instead, gas and its infrastructure became monumental testaments to the independence and progress of Iranian society. For the government planners who made gas part of the broader state-directed modernization efforts then in full swing, the new fuel source promised to power Iran’s accelerating industrialization while also permitting most of the country’s oil to still be sold abroad. Yet natural gas promised still greater benefits: the potential to alleviate Iran’s worsening air quality crisis. By replacing the oil-based fuels then in widespread use, gas brought hope that a smoke-clouded future for Iran’s cities could be avoided. Going beyond histories of industrial and economic growth, this paper aims to shed light on the crucial role that environmental concerns and attempts to address them played in the history of Iranian modernization. In the 1960s, academics and government planners began setting out expectations for the environmental benefits natural gas could bring for Iranian society. Iranian cities had started to choke on the fumes produced by rapidly proliferating workshops and motor vehicles, drawing complaints from as high as the royal family. Claims that gas could improve Iran’s air quality were tested in the 1970s, when factories across the country were converted over and a trial study for gas-powered buses was conducted in the capital. Brick kilns and asphalt plants were quickly identified as major polluters, and between 1974 and 1977 plans were set in motion to convert them to gas. Complications arose as factory owners objected to the high cost of the imported equipment, and despite the eventual conversion of the workshops, the matter pit environmental protection and its costs against overarching goals of rapid industrial development and economic growth. For Tehran’s public transit experiment, the limiting factor was not politics but technology. Inspired by the example of Tokyo, between 1975 and 1979, routes featuring gas-powered buses were established. Despite significant public attention, the test failed as the expensive foreign buses struggled to operate in the city’s notoriously hilly terrain. With these two episodes, this paper, based primarily on archival sources, studies the ability of natural gas to bridge the gap between rapid development and environmental protection, ultimately exploring the extent to which clean air and city dwellers’ quality of life were prioritized.