A deadly smog blanketed a western Pennsylvania town from the October 27 to 31 in 1948, killing over a dozen people and hundreds of animals.

The dangerous weather event is officially known as the "1948 Donora smog" which killed approximately 20 people and 800 animals, as well as sickened 7,000 people.

It was caused by a trapped air pollution, which will pave the way for a greener future.

Almost eight decades ago, several days before the Halloween saw residents of the Pennsylvanian town of Donora waking up in a scene out of a sci-fi horror movie.

A thick plume of fog covered their community and the event consists of smog and airborne pollutants as well.

Within four days, most of the victims died due to asthma-related ailments or respiratory problems triggered by the deadly fog.

It was only until rain cleared out the smog local authorities and inhabitants of the small industrial town realized the magnitude of the unprecedented disaster.

The 1948 Donora smog was regarded as the worst air pollution in the history of the United States.

However, the event would lead to awareness of the growing threat of human-induced air pollution combined with the dangers posed by climate change.

The Donora Smog of 1948

smog pollution
Photo by George Frey/Getty Images

Prior to the foggy incident, Donora, which is about an hour's drive south of Pittsburgh, was reportedly proud of its industrialization, and its people were reliant on industrial plants for their livelihood.

This actually the case even if their work heavily contributed to pollution.

During such time, Donora residents worked for two local steel and wire manufacturing plants.

Donora Historical Society volunteer Mark Pawlewec told AccuWeather that Donora was considered a bustling town in the 1940s, wherein some individuals living in the town and working at the mill immigrated to the community for various reasons.

These people survived and experienced World War I, the Great Depression of the economy, and World War II, Pawlewec added.

In spite of the local economic progression, a weather phenomenon called "temperature inversion" occurred in the area in October 1948 and produced a choking smog, according to the US weather forecasting company.

Dawn of Environmental Protection

The Donora town smog of 1948 sparked the dawn of environmental protection in the succeeding decades, heeding lessons from the past about the dangers of steel and zinc industries.

These sectors provided the Donora residents with work but also endangered their health and took some of their lives, according to the Smithsonian Magazine.

The looming threat reached its toll during the Donora Halloween parade when a yellow fog descended into the town and caused a nearly impenetrable haze and zero visibility.

Residents exposed to the toxic air mass reportedly had difficulty in breathing.

In contemporary times, the occurrence of smog is no longer a mystery ever since we have determined that the main ingredients of a photochemical smog are caused by ground-level ozone and particulate matter, which also occurred in Los Angeles, California, and other urban areas, according to the California Institute of Technology.