A mysterious fog enveloped the land, alarming residents who fear it may be a biological weapon (photo).

During one week in September 1950, the U.S. Navy released a vast amount of bacteria into the air just 3 kilometers off the coast of San Francisco, California. The aim of this secret experiment in biological warfare was to determine how vulnerable major American cities, such as San Francisco, were to a biological attack by terrorists, reports Daily Mail.

At that time, researchers utilized Serratia marcescens bacteria, which can cause respiratory issues and meningitis, as well as Bacillus atrophaeus, which can be lethal for individuals with weakened immune systems. It is important to note that the U.S. Navy considered these bacteria harmless to humans at that time.

Unfortunately, after the experiment, residents of the coast began seeking medical assistance. It soon became clear that inhaling thousands of bacterial spores was quite unsafe: 11 individuals were hospitalized with rare and severe urinary tract infections, which doctors ultimately identified as related to the experiment.

Seventy-five years have passed since the experiment, and now some Americans fear that it could happen again, as they claim that an "unnatural" fog with a "burnt chemical-like smell" has been affecting communities in recent weeks. Some witnesses also report that the fog caused symptoms resembling respiratory illness.

Residents of Florida who unfortunately found themselves outdoors during the fog report feeling unwell just 10 minutes after exposure. Approximately an hour later, sneezing continued, and their eyes remained swollen for about three hours. One witness also felt feverish, and experienced stomach cramps.

It is worth noting that warnings about the fog were issued this week across several states, including Texas, Wisconsin, Iowa, Maryland, Virginia, West Virginia, Nebraska, Kansas, Oklahoma, North Dakota, Florida, and Minnesota. Similar incidents have also occurred in parts of Canada and the UK, raising widespread concern.

As a result, more conspiracy theories are emerging online. People are worried that the fog could be a form of chemical weapon or linked to drones that have mysteriously flooded the entire country. The latest theory suggests that the U.S. government is behind the fog, potentially testing a new type of biological weapon.

At the same time, the National Weather Service (NWS) issued a dense fog advisory for several states at the time these reports surfaced, suggesting a scientific explanation for the fog.

Researchers acknowledge that the appearance of the fog as "white particles" may seem unusual, but it is not entirely so. Scientists note that fog is a visible aerosol made up of tiny water droplets or ice crystals suspended in the air near the Earth's surface. In simple terms, if the fog is illuminated, these particles become visible.

According to atmospheric scientist Rudolf Husar from the University of Washington, when fog forms, sulfur oxides, nitrogen oxides, and other pollutant gases are absorbed or "washed out" by the water droplets in the fog. This also explains the odor. Moreover, odors become more pronounced in humid air because the water droplets hold onto the odor-causing molecules, allowing them to linger longer and remain concentrated.