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.

The US Food and Drug Administration (FDA) has approved Merck's Idvynso (doravirine/islatravir), a new, once-daily pill for the treatment of HIV-1 infection in adults.

The two-drug single tablet replaces the current antiretroviral regimen in those who are virologically suppressed (HIV-1 RNA <50 copies per mL).

The single tablet contains 100 mg doravirine and 0.25 mg islatravir. The FDA has approved it for adults on a stable antiretroviral regimen with no history of virologic treatment failure and no known substitutions associated with resistance to doravirine.

“IDVYNSO combines islatravir, a next-generation NRTI with multiple mechanisms of action, including translocation inhibition, with doravirine, an NNRTI with an established efficacy and safety profile,” said Dr. Eliav Barr, senior vice president and chief medical officer, Merck Research Laboratories, in a statement.

How Was The Pill Approved?

The approval is based on data from two randomized, active-controlled, noninferiority trials. In the double-blind Trial 052, participants were randomly assigned to stay on Glilead's Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide; 171 individuals) or switch to Idvynso (342 individuals).

Results showed that 1 per cent of participants in both groups had a viral load of ≥50 copies/mL at 48 weeks.

In the open-label Trial 051, participants were randomly assigned to stay on their oral antiretroviral therapy (ART) regimen (185 individuals) or switch to Idvynso (366 individuals).

Results showed that 1 per cent of participants who were switched to Idvynso had a viral load of ≥50 copies/mL at week 48 versus 5 per cent who continued on ART.

"As the only two-drug, non-integrase strand transfer inhibitor, tenofovir-free regimen, Idvynso expands therapeutic diversity beyond the currently available oral treatment options," Barr said.

"As the health needs of adults living with HIV change over time, Idvynso gives clinicians a new choice for HIV treatment."

What Is IDVYNSO? How Does It Work?

IDVYNSO is a fixed-dose combination of two medicines, doravirine with islatravir.

Doravirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that inhibits HIV-1 replication by non-competitive inhibition of HIV-1 reverse transcriptase.

Islatravir is a potent, next-generation nucleoside analog reverse transcriptase inhibitor (NRTI) that blocks HIV-1 replication by multiple mechanisms, including:

• inhibition of reverse transcriptase translocation, resulting in immediate chain termination,
• induction of structural changes in the viral DNA (delayed chain termination).

Global Burden Of HIV

According to the latest data from UNAIDS, 40.8 million people globally were living with HIV in 2024. Of these, 39.4 million were adults (15 years or older) and 1.4 million were children (0–14 years).

While 1.3 million people became newly infected with HIV in 2024, 630,000 died from AIDS-related illnesses.

About 87 per cent of all people living with HIV knew their HIV status, and 5.3 million people did not know that they were living with HIV.

The US eliminated measles in 2000, but since 2025, the highly infectious disease has spread to 45 states. As of early May 2026, the US has recorded 1,814 confirmed measles cases this year across 36 states. This follows a record-high 2,288 cases in 2025.

Now, the US Centers for Disease Control (CDC) has warned about additional measles cases ahead of the travel season.

The CDC urged public health agencies across the US to be prepared for more measles cases in the coming months.

"With continued measles transmission in areas across North America and expected increases in international and domestic travel and large events during spring and summer, additional measles cases are anticipated in the coming months," the agency said.

Travel Guidance By CDC

The guidance advised public health agencies to document and report details of each case of measles, including close contacts and locations visited while a person was infectious.

Active surveillance should be conducted to identify any additional suspected cases and quickly transport specimens for laboratory confirmation, the guidance said.

The agency also encouraged outreach to under-vaccinated communities and suggested using state-based syndromic surveillance systems to detect changes in health care–seeking behavior for fever and rash illnesses or signs of vitamin A toxicity.

Measles is a highly contagious virus that spreads through direct contact or through the air when an infected person coughs or sneezes. It is a vaccine-preventable disease that can cause devastating complications, including blindness, pneumonia, encephalitis, and long-term immune dysfunction.

Is The US At Risk Of Losing Measles Elimination Status?

Also read: Robert F. Kennedy Jr. Denies Link To Measles Outbreak At Senate Hearing

So far, there have been 24 new outbreaks reported in 2026, and 93 per cent of confirmed cases (1,688 of 1,814) are outbreak-associated (415 from outbreaks starting in 2026 and 1,273 from outbreaks that started in 2025).

In 2025, 48 outbreaks were reported, and 90 per cent of confirmed cases (2,065 of 2,288) were outbreak-associated.

According to researchers at Boston Children's Hospital, the US has missed four of the seven criteria for measles elimination status, which could put the country off track. More are at risk, they said.

In a Correspondence published in The Lancet, the researchers explained the missed indicators of measles elimination status in the US.

• Low number of cases with a cutoff of less than one case per 10 million people. As of early 2026, the US had about 93 cases per 10 million people, exceeding this limit.

• Most of the measles cases should come from abroad rather than from internal spread. Since the start of 2025, only 6–7 per cent of the measles cases have come from abroad, meaning most cases derive from within the US.

• A limited number of outbreaks (a cutoff of approximately four) with no more than about six cases each. Last year in the US, 48 outbreaks resulted in more than 2,000 cases. And in early 2026, at least 19 outbreaks have already resulted in more than 1,600 cases.

• A level of transmission less than one, meaning one infected person only spreads measles to fewer than one other person on average. The US exceeded this rate more than 75 per cent of the time since early 2025.

Indicators At Risk

Read More: India Concerned Over Measles Outbreak, Action Underway: Dr N K Arora| Exclusive

• The country achieves four weeks with all infections deriving from outside the US. Since the first infection in January 2025, the US hasn't gone four weeks without infections, with 90 per cent of cases acquired here.

• Herd immunity through vaccination. An estimated 95 per cent of people need to receive two doses of the measles vaccine to achieve herd immunity, typically given as part of the MMR (measles, mumps, and rubella) vaccine. However, the US average vaccination rate of kindergartners in the 2024–2025 school year was 92 per cent, meaning this indicator is at high risk.

• Measles cases don't share a common viral strain. From ongoing genetic analyses, preliminary data show that the majority of cases share the same viral strain and are likely part of the same transmission chain.

The researchers believe these findings make a strong case for vaccinating children to protect them from a young age.

"Viral infections aren't all benign, and a measles infection, even when cleared, can result in lifelong problems," said Maimuna Majumder, from Boston Children's.

"Babies less than a year old are among those at greatest risk for severe complications, and the full impact on children exposed during the current outbreak may only show up years later," Majumder added.

Pancreatic cancer is one of the most painful forms of tumour and is also likely to become the second-leading cause of cancer-related deaths in the US by 2030. This could be because 85 per cent of cancer cases in the US are not diagnosed until the disease has spread. Pancreatic cancer is a disease that is usually diagnosed at an advanced stage because there are no prominent early signs. However, a newly developed AI model from the Mayo Clinic and the University of Texas MD Anderson Cancer Center could change that—a new CT scan-based system can help with the timely diagnosis of pancreatic cancer.

Can AI help with pancreatic cancer diagnosis?

REDMOD (radiomics-based early detection model) was tested on CT scans of patients who were later diagnosed with pancreatic cancer. Researchers found that in nearly three out of four cases, REDMOD successfully identified the most common form of pancreatic cancer 16 months before diagnosis. It nearly doubled the detection rate of specialists reviewing scans without AI assistance. In some cases, REDMOD recognised suspicious tissue patterns more than two years before diagnosis. Researchers said that the AI system can detect cancer up to three years in advance.

How does AI work for pancreatic cancer diagnosis?

Experts found that the greatest barrier to saving lives from pancreatic cancer was the inability to detect the tumour when it was still curable. AI can identify cancer signs from a normal-looking pancreas, and it can do so reliably across clinical settings. Researchers used 969 CT scans of the pancreas as training data for REDMOD to help it detect early-stage cancer signs.

Instead of looking for a prominent tumour, the model analysed radiomic patterns that disrupt tissue structure and texture—changes that are too subtle for the human eye to detect. Many cancers begin when normal cells acquire DNA mutations, which affect how cells divide and grow. However, it can take years before these changes develop into a tumour that produces symptoms or becomes clearly visible on a scan.

How accurate was REDMOD at diagnosing pancreatic cancer?

REDMOD was tested on a varied set of CT scans after training — 63 from patients who later developed cancer but were scanned before diagnosis, and 430 from healthy individuals. Out of the 63 cases, REDMOD flagged 46 as suspicious, resulting in a 73 per cent success rate. All these scans had previously been given the all-clear by radiologists who evaluated them at the same time as REDMOD.

Out of the 430 healthy individuals, 81 were identified as suspicious cases by REDMOD. This means that if AI were deployed in a real-world scenario, some individuals might be recommended for additional tests before receiving a final all-clear. A similar performance was observed in two other datasets from different hospitals using different equipment. For patients who had multiple scans available, AI produced consistent results, even when the scans were taken months apart.

Are there any drawbacks of REDMOD?

The sooner REDMOD is implemented in clinical practice, the earlier it can detect pancreatic cancer. It could identify tumours at a stage when treatment is still possible. This could significantly improve survival rates and reduce cancer-related mortality. However, researchers now aim to test the effectiveness of AI in larger and more diverse populations.

The research has been published in the Gut.