Mysterious Fog in the US , Canada and UK: A dense, eerie fog with a "burning chemical-like smell" has spooked a good part of North America and parts of the United Kingdom and Canada. With social media amplifying all concerns, this phenomenon has sparked attention across all social media platforms. However, at the heart of this mysterious fog are a conjunction of natural events, social psychology, and environmental conditions that culminated in all the conspiracy theories and public health fears. Here's a closer look at the mysterious fog, its potential causes, and the societal response it has triggered.

Fog that Feeds Fear

The first reports of this "mysterious fog" came in from Florida where a resident said that they experienced respiratory symptoms, feverish warmth, and stomach cramps after contact with the fog. Similar stories started flooding social media, and within a day or two, a sinister force seemed to sweep across the United States, Canada, and parts of the UK. From Texas to Minnesota, people reported weird odors and health issues that they thought were linked to this bizarre atmospheric event.

Some witnesses were said to see "white particles" swirling through the air; theories ranged from a chemical attack or experimental weapon to drone-related chemical dispersals and references to historical military experiments, such as the infamous 1950s "Operation Sea-Spray."

Fuel to the fire were added when videos and posts, hundreds of thousands in number, began circulating on social media sites like TikTok and X (formerly Twitter) speculating on the origin of the fog. Hashtags like #ToxicFog went trending for days. Hysteria created a self-reinforcing loop in which every post spurred further scrutiny and fear.

Scientific Explanation of the Dense Mysterious Fog

1. What is Fog?

Fog is essentially a low-lying cloud formed when the air temperature cools to its dew point, causing water vapor to condense into tiny droplets or ice crystals. Several types of fog—advection fog, radiation fog, and valley fog—can form depending on conditions such as warm, moist air moving over cooler land or when temperatures plummet rapidly under clear skies.

2. Why the Chemical Smell?

Such chemical-like smell as reported during the occurrence of fog events is sometimes attributed to air pollution. It acts like a sponge, where it absorbs these pollutants, which include sulfur dioxide and nitrogen oxides, among others, that emit from industries. This mixture, therefore, leads to a stench that could be mistaken as unnatural or even toxic.

Also Read: Health Concerns Rise As US, Canada, and UK Come Under The Blanket Of Thick, Dense, Toxic Fog

3. What are the Health Concerns?

High moisture levels from fog can significantly exacerbate symptoms related to respiration, but especially in already predisposed asthmatics and allergy patients. The connection of these symptoms with actual fever, stomach cramps, and puffy eyes is too remote. Experts assume that the irritating effects of entrapped pollutants trapped in fog tend to affect more the eyes and throat rather than the rest of the body affected by some report.

Psychological Effects of Mass Panic Caused by Social Media

Social media amplified a natural weather event into a health epidemic. It made the personal experience of individuals become a cause for fear and speculation, a domino effect.

According to psychologists, this is a concept of selective perception, wherein once people's attention is drawn to environmental anomalies, they begin to notice them. This mirrors earlier panics, such as the Seattle windshield pitting panic of 1954. Then, atomic bomb testing caused fear in many and started to have people looking at their windshields for small marks that they had not seen before. Likewise, postings on the strangeness of the fog probably increased public awareness and suspicion, with people looking to attach unrelated symptoms to the phenomenon.

The fog hysteria shares a commonality with other instances of mass panic, such as the "drone sightings" of recent years or the Cold War-era fears of biological warfare.

Also Read: Mysterious Fog Is Making Americans Sick

These events underscore how fear can cloud judgment, especially when amplified by social media and sensationalist headlines. While historical cases, such as "Operation Sea-Spray," offer concrete evidence of the existence of unethical experiments, the jump from a natural weather condition to theories of chemical attacks exemplifies a more modern trend of connecting unrelated dots, all wonderfully seeded in distrust and anxiety.

Despite the swirling rumors, meteorologists and scientists are in agreement that the mysterious fog is not as alarming as it seems. It is well known that fog traps and amplifies pollutants, especially in urban and industrial regions. Moreover, winter months are the most conducive for fog formation, so its recent prevalence is unsurprising.

On the other hand, environmentalists advise that the fog should wake everyone up to increased levels of pollution. The reported odors and health irritations could be just symptoms of far deeper systemic issues like industrial emissions and lack of control over air quality.

The authorities must be transparent in their communication to combat misinformation and allay public fears. Governments and environmental agencies must provide timely updates on weather phenomena, air quality, and health risks. Initiatives like real-time pollutant tracking and public education campaigns can help demystify natural occurrences while addressing valid environmental concerns.

The mysterious Canada fog is a compelling case study in how environmental events intersect with psychology and societal dynamics. While rooted in natural phenomena, the fog became a vessel for collective fears, amplified by modern technology and historical anxieties.

In this information era where communication occurs at an almost lightning pace, the fog becomes a metaphor that reminds everyone about scientific literacy, environmental responsibility, and an effective balance when considering public concern. Whether perceived as a marvel of nature or as a tale that serves to teach, it left a very powerful mark in people's minds.

Plague is highly treatable if caught early, newly appointed CDC Director Erica Schwartz said, adding that the US is monitoring travelers arriving from Siberia following the reported death of a worker in Russia.

Speaking at the WSJ’s Future of Health event, Schwartz said the risk to the US from an unconfirmed case of pneumonic plague in Siberia was extremely low. She noted that the reported illness involved Yersinia pestis, the bacterium that causes plague.

“It’s a bacterial disease, a very serious bacterial disease. The one good thing is that it’s a treatable, highly treatable bacterial disease with common antibiotics that most physicians within the United States can utilize,” Schwartz said.

“This is a disease that is spread person to person through respiratory droplets, but as I said, if we can identify cases early, they’re absolutely treatable,” she added.

Read More: Russia Plague Scare: Could It Trigger A New Pandemic? Experts Explain

Schwartz said the CDC was prepared to monitor and screen travelers, particularly those arriving from Russia. She also discussed steps public health officials are taking to ensure Americans are protected from a potential threat linked to the reported case in Russia.

“There are about 200 flights that come into the United States from Siberia, that region. We are working with Department of Homeland Security, working (with) Department of State, Department of War, and other agencies within the government to make sure that we know exactly if anyone from that area comes into the United States,” Schwartz said.

She said flights from Siberia, where the plague-linked Irkutsk Anti-Plague Research Institute is located, typically arrive at JFK International Airport.

“We have a port health station set up in JFK so that we can do appropriate surveillance and screening if anyone from that area comes into the United States. So we’re very well positioned to make sure that we are protected from a potential threat like that,” Schwartz said.

An HHS spokesman said about 200 individuals per year from the Siberian region travel to the United States. Direct flights between Russia and the United States have been suspended since the start of the Ukraine war in 2022.

Also Read: Russia Plague Scare: Is Pneumonic Plague Deadlier Than Bubonic & Septicemic Plague?

Russia Plague: What We Know So Far

Russia has reportedly seen two deaths allegedly linked to pneumonic plague. One was Darya Shipilova, a 28-year-old laboratory technician at the Irkutsk Anti-Plague Research Institute. The identity of the other person remains unknown.

Shipilova fell ill on September 29, was placed on a ventilator, and died on October 2. Around 200 contacts were reportedly placed under medical observation after she allegedly told doctors that she had accidentally broken a test tube containing live bacteria.

However, Russian authorities maintain that Shipilova died from “unidentified pneumonia”. Authorities said tests of her contacts found no dangerous infectious-disease pathogens, although some reportedly tested positive for COVID-19 or rhinovirus.

Russia has also denied reports of a second death linked to plague, calling them “fake news”.

In a statement published by Russian news agencies, the regulator denied what it called “fake information circulating on social media regarding a second case of illness”.

It said it had completed checks on all contacts of the dead woman, adding that “no health issues related to an infectious disease were detected” and that nearly 5,000 laboratory tests showed no dangerous pathogenic microorganisms, Reuters reported.

US President Donald Trump and Senator Rand Paul have publicly criticized Russia’s handling of the situation, with Trump calling it a “big problem for Russia” and Paul accusing Russia of not fully cooperating with international health authorities.

The XFG COVID-19 variant is driving a rise in cases and hospitalizations in the UK and France, while some US regions are also reporting increases.

XFG, nicknamed ‘American COVID’ or Stratus, is a recombinant SARS-CoV-2 variant from the Omicron lineage, formed from LF.7 and LP.8.1.2. The WHO recorded the earliest documented XFG sample on January 27, 2025, and designated it a variant under monitoring in June 2025.

The NHS has advised infected people to stay home to limit spread. The UK is rolling out COVID vaccination, while France is expected to begin its campaign next week.

COVID and flu symptoms can overlap, including cough, fever, sore throat, headache, runny nose and fatigue.

COVID Activity Rises in UK, France

In France, the estimated number of people with COVID consulting GPs for acute respiratory infections rose to 13 per 100,000, from nine the previous week, according to The Connexion. This translates to around 8,806 new cases, up from about 6,000.

In England, hospital PCR positivity rose from 5.9% to 7.0% in the week to September 20, while hospital admissions increased from 0.81 to 1.20 per 100,000. Overall activity remained low.

US CDC data from September 29 showed cases rising in some states while falling or remaining stable in others.

Also read: ‘American Covid’ Strain Drives 50% Surge in UK Hospital Admissions: XFG Symptoms to Know

Is India At Risk?

HealthandMe spoke to experts who said the UK-France rise does not necessarily mean India will see a similar increase.

“The rise in COVID-19 cases in the UK and France does not necessarily mean that India is headed towards a similar increase,” said Dr Suranjit Chatterjee, Senior Consultant, Internal Medicine, Indraprastha Apollo Hospitals, Delhi.

XFG is being monitored because it has become more common in some countries, but available evidence does not indicate that it causes more severe illness than other circulating variants.

“For India, the more relevant question is whether XFG is increasing locally and whether this is translating into a rise in symptoms or hospitalizations,” Dr Suranjit told HealthandMe .

Does XFG Cause More Severe Disease?

Dr Amit Prakash Singh, Consultant - Internal Medicine, CK Birla Hospital, Delhi, said the spread of XFG highlights the need for continued surveillance as SARS-CoV-2 evolves.

“Yet at present there is no evidence to indicate that the XFG variant causes more severe disease than the other Omicron-lineage variants,” he said.

However, the “main concern for India would be a greater rate of transmission, especially among older people, those with comorbidities and the immunocompromised, should the variant become more common in the country”.

What Should India Watch?

Read More: COVID-19 Cases Rise In France, Vaccination Campaign Set To Start Next Week

Dr Amit told HealthandMe India should continue genomic surveillance and monitor hospitalizations and severe disease rather than focusing only on case numbers.

Dr Suranjit said international travel can introduce new variants, but their impact depends on community spread and existing immunity.

“At this stage, there is no reason for people (in India) to be unduly concerned or change their daily routine.”

He added that continued surveillance, timely testing when symptoms occur and sensible precautions during respiratory infections remain appropriate.

Are XFG Vaccines Available?

XFG-specific vaccines have been developed and are either in use or authorized in several countries. The US and UK have opted for XFG-targeted formulations for the 2026–27 season.

In India, an XFG-specific vaccine should be considered available only after regulatory approval and commercial supply.

The WHO continues to stress that vaccination should not be postponed while waiting for an updated formulation.

Canada has determined to restrict medical assistance in dying (MAID) for patients whose sole underlying condition is a mental illness, shelving plans to expand the eligibility in 2027.

Justice Minister Sean Fraser said the government will introduce legislation to maintain the exclusion beyond the current deadline of March 17, 2027.

The decision comes weeks after an Ontario court rejected a woman's request for an exemption that could have allowed her to seek MAID because of severe, longstanding mental illness.

Canada Extends Ban On Medical Assistance In Dying

The government says there is still no sufficient medical consensus on when a mental illness can be considered irremediable, a key requirement under Canada's MAID policy.

Fraser said, “When I hear that there is a lack of consensus within the medical community about the irremediable nature of certain mental illnesses, that gives me real cause for concern.” He also pointed out that access to mental health care in the country is uneven.

He acknowledged that the issue does not have unanimous agreement but defended the government's decision. “While there is not a perfect consensus on this issue, we believe this is the correct approach at this particular time,” Fraser said.

Canada had originally kept the exception as temporary. When MAID eligibility was expanded in 2021 to people whose natural death was not reasonably foreseeable, mental illness as the sole underlying condition that was deemed ineligible.

The exclusion was subsequently delayed several times, with March 2027 becoming the latest planned date for possible expansion.

Also read: Canadian Parliamentary Panel Urges Indefinite Ban on Assisted Dying for Mental Illness Alone

Ontario Court Rejected A Woman’s MAID Request

The announcement comes just after a controversial case involving Claire Elyse Brosseau, a 49-year-old Toronto woman who sought a constitutional exemption from the existing MAID exclusion.

Brosseau said she has lived with severe mental-health problems for decades and had undergone multiple forms of treatment. In May, she asked the Ontario Superior Court for emergency relief that would allow her to apply for MAID.

On September 3, Justice Carissima Mathen rejected that request. She also ordered the federal government to respond to Brosseau's constitutional challenge to the exclusion.

Mathen described Brosseau's evidence of suffering as credible and compelling, but said the case also involved Parliament's role in making decisions on “sensitive social issues” and interpreting the Charter rights involved.

Brosseau, meanwhile, said the decision was nothing but another barrier for people with mental illness. “It is yet another example of governmental systems telling people with mental illnesses that we do not have the same rights nor the same autonomy as others,” she said.

Also read: Impact Of Canada’s Delay In Approving MAID For Mental Illness: Patients Say They Feel Abandoned & Hopeless

Parliament Had Already Recommended An Indefinite Exclusion

The government's decision also follows a recommendation that was passed in June from a joint parliamentary committee, which called to exclude people from MAID eligibility whose only underlying condition is mental illness.

The committee's review highlighted disagreements among experts over whether clinicians can reliably determine that certain mental illnesses are permanently irremediable.

It was based on a report that noted a "divergence of perspectives" on the issue and highlighted concerns raised during testimony about the "pressing need for increased and more equitable access to adequate mental health services".

However, the recommendation was not unanimous. Four senators issued a dismissed the report, questioning the committee's process, arguing that the government should consider seeking guidance from the Supreme Court of Canada.

Also read: New York Assisted Suicide Law: Nearly 20 People Reportedly Died Since August

The government's proposed legislation is expected to circle back to advance requests, which is another another debatable aspect of MAID.

Under the proposed changes, people diagnosed with serious illnesses who may eventually lose the ability to consent could be able to make an advance request for MAID.

According to the latest available figures from 2024, MAID accounts for around 5 per cent of all deaths in Canada. About 96 per cent of MAID cases involved people whose deaths were reasonably foreseeable, most of them terminal cancer patients.

The remaining 4 per cent involved patients whose deaths were not imminent but who had a "grievous and irremediable medical condition".