Donora is a small borough located in Washington County, Pennsylvania, United States. It is situated along the Monongahela River and is part of the Pittsburgh metropolitan area. Founded in the late 19th century, Donora was known for its steel and zinc industries, which played a significant role in its economic development. The borough gained national attention in 1948 due to a severe air pollution event known as the Donora Smog. This incident resulted from emissions from local factories and weather conditions, leading to health issues for many residents. Today, Donora is a quieter community, with a focus on preserving its history and improving air quality.