Public Health

Authors:

• Bhavini Gohel | Clinical Associate Professor, Cumming School of Medicine, University of Calgary
• Muskaan Muse Laroyia | MSc Candidate & Graduate Researcher, Neuroscience, Hotchkiss Brain Institute, University of Calgary

Anyone who has experienced wildfire smoke knows how it can leave you with a scratchy throat, stinging eyes and impact your lungs. However, smoke can also affect your brain. Tiny airborne pollutants found in smoke have been linked to increased risk of stroke, dementia and flare-ups in neurological diseases like multiple sclerosis (MS).

Alongside harmful gases and heavy metals, wildfire smoke contains fine particulate matter, also known as PM2.5. These tiny particles can travel deep into your lungs, slip into your bloodstream and even reach your brain. Some even bypass the lungs entirely, entering the brain directly through the nose.

After entering the brain, these toxins can cause inflammation and stress, damage nerve cells and even accelerate cognitive decline. Studies have linked exposure to air pollution to an increased risk of stroke and dementia. Even short-term spikes in smoke exposure, like those during wildfires, lead to a surge in emergency visits for strokes, especially among people over 65.

A 2022 experiment had thousands of adults participate in an online attention task under smoky conditions. It found that just a three-hour spike in fine particulate matter, typical of a heavy smoke episode, led to measurably worse attention scores. This fits other evidence that breathing smoke makes people mentally foggy, forgetful or fatigued.

As cannabis use among youth rises in Canada — and THC potency reaches record highs — emergency departments are seeing a surge in cases of a once-rare condition: cannabis hyperemesis syndrome (CHS).

Characterized by relentless vomiting, abdominal pain and temporary relief through compulsive hot showers or baths, CHS is increasingly affecting adolescents and young adults. Yet few people — including many clinicians — know it exists.

Canada ranks among the highest globally for youth cannabis use, with 43 per cent of 16-19-year-olds reporting use in the past year. Usage peaks among those 20–24 years, with nearly half (48 per cent) reporting past-year use.

This rise in regular, heavy use coincides with a 400 per cent increase in THC potency since the 1980s. Strains with THC levels above 25 per cent are now common. As cannabis becomes more potent and accessible, clinicians are seeing more cases of CHS, a condition virtually unheard of before 2004.

CHS unfolds in three phases:

1. Prodromal phase: Nausea and early morning discomfort begin. Users increase cannabis consumption, thinking it will relieve symptoms.

2. Hyperemetic phase: Intense vomiting, dehydration and abdominal pain follow. Hot showers or baths provide temporary relief — a hallmark of CHS.

3. Recovery phase: Symptoms resolve after stopping cannabis entirely.

Diagnosis is often delayed. One reason is because CHS mimics conditions like gastroenteritis or eating disorders, leading to costly CT scans, MRIs and gastric emptying tests. One telltale sign — compulsive hot bathing — is frequently overlooked, despite its strong diagnostic value.

Youth face unique risks. The brain continues to develop until about age 25, and THC exposure during this critical window can impair cognitive functions like memory, learning and emotional regulation. Heavy cannabis use is associated with heightened risks of anxiety, depression, psychosis and self-harm.

I was glad to hear from BBC crowd science (the linked show) that I’m not alone in hearing a hum. People around the world hear a low frequency (50 Hz) hum.

What I hear often when waking up in the morning is a high pitch buzz, comparable to the sound of your ears ringing the day after a concert. My theories:

• it’s microwave radiation, perhaps from wi-fi
• the eardrum itself is making noise due to a physiological condition, despite not being around loud noise (BBC mentions this as well)

I recall hearing about a woman who could hear wi-fi, to the surprise of scientists who would emit supersonic sounds and the woman would raise her hand to indicate when she hears a sound. IIRC, she moved to live in a small region where wi-fi is banned to prevent interference with an array of radio telescopes.

Here’s another link to past stories:

• https://www.tinnitusjournal.com/articles/manifestations-of-a-lowfrequency-sound-of-unknown-origin-perceived-worldwide-also-known-as-the-hum-or-the-taos-hum.html
• https://www.theguardian.com/cities/2019/mar/16/can-you-hear-the-mysterious-global-hum-apparently-many-of-you-do

I am not quite sure I would call the hum low pitched. What I hear is very similar to the ringing ears experience after a concert. Isn’t that a high pitch?

I have to say I’m bothered that the research for this requires participants to use Google. I will not submit records to the project because of that.

cross-posted from: https://sh.itjust.works/post/39836237

Recent Veritasium video on per- and polyfluoroalkyl substances.