As per the World Health Organization, all but 1% of the world's population is exposed to unhealthy air and also exceeds the WHO limits for pollutants. However, there are some parts of the world where aur quality has improved through policies that limits pollution, while in other parts, it has not reached the desired results.

For US, more than 25% of the population is exposed to "unhealthy" air as per the Environmental Protection Agency (EPA), this is according to the report by the climate non-profit First Street Foundation. By 2050, the number of people exposed to "unhealthy" air will increase by more than half. The worst days of air pollution, reports BBC, "hazardous" or maroon under the EPA's system will rise by 27%.

Why are we talking about this today? It is because of the recent wildfire in California, which started on January 7. This is also one of the factors that is spiking the PM2.5 levels. It has increased by up to five micrograms per cubic metre in the western US in the past decade.

What is PM2.5?

It is a type of air pollution which is made of particulate matter and measures 2.5 micrometres across or less. It is roughly 30 times smaller than the width of a human hair. These particles are made with a mixture of solid and liquid substances, which varies in their chemical composition, including carbon, metals, and organic compounds.

These specks of airborne soot, dust and other substances can also trigger inflammation, which could also damage your brain.

As per a 2021 study titled The Changing risk and burden of wildfire in the United States, a quarter of US's PM2.5 pollution was caused by wildfire smoke. In 2023, US also witnessed a significant dip in air quality and visibility as smoke from wildfires north of the Canadian border entered across the continent. In May 2024, Canada also saw a start to its wildfire season, and one town was evacuated in British Colombia.

Wildfire smoke and its effects

Wildfires do not only affect those who live near forests, peatlands, and grasslands, but also to the cities and environment in general. It can send plumes up to 14 miles or 23km into the stratosphere, and from there, it can spread all over the globe. For instance, in 2023, the Siberian wildfires released smoke that travelled across the Pacific Oceans to reach Alaska and Seattle.

Other than PM2.5, wildfire smoke is also harmful to immune cells in lungs, and the toxicity could be four times greater than particulates from other types of pollution.

Another 2019 study titled Effects of Atmosphere Processing on the Oxidative Potential of Biomass Burning Organic Aerosols found the toxicity of smoke doubled in the hours after it was first emitted and reached four times greater toxicity at its peak.

Health Impact

There have been research that shows how pollution affects your brain. It can lead to impaired judgment, poorer performance in school and even higher levels of crime, as per the 2018 study by the London School of Economics.

Other health concerns include weight gain. There have been researches that links airborne pollution such as PM2.5 to obesity. The studies have found that children who live in most polluted areas are twice as more likely to have obesity. Some studies also find the link of air pollution harming our sense of smell. As per an Italian study from 2022, titled Association between environmental air pollution and olfactory functioning among Italian adolescents and young adults in Northern Italy, noses of teenagers and young adults became less sensitive to odors after being exposed to nitrogen dioxide, which is a component in traffic fumes.

From physical problems like fatigue and vision problems, people who survive the deadly bacterial meningitis are likely to live with long-term fatigue and vision problems, as well as be at high risk of suicide, according to a new study.

The study comes as the UK is experiencing an outbreak of meningitis in Kent, that began among students who visited Club Chemistry in Canterbury between March 5 and 7.

Although bacterial meningitis is treatable, it requires prompt, often immediate treatment for better recovery. Yet patients are likely to face the risk of fatal or long-term complications -- from physical, psychological, and social impacts, said researchers from the University of Otago, The Conversation reported.

The new findings, based on 16 cases from New Zealand, who reportedly suffered the fatal disease, showed that multiple chronic after-effects is permanent in some, while in others, it dragged on for years. The effects include:

• fatigue,
• difficulties with concentration,
• memory and emotional regulation,
• persistent headaches,
• issues with mobility, vision, and hearing.

• anxiety,
• depression
• suicidality.

"Our findings demonstrate that bacterial meningitis is much more than a life-threatening infection. It is an acute disease with serious, chronic after-effects which are poorly understood and often go unrecognised," the researchers said.

Kent Meningitis Outbreak

The bug that causes the infection has been identified as the known strain of meningitis B, and MenB vaccines will be offered to 5,000 students living in the University of Kent halls of residence in Canterbury.

Meanwhile, the UKHSA chief executive, Susan Hopkins, said the outbreak "looks like a super-spreader" event with "ongoing spread" through universities' halls of residence.

"There will have been some parties, particularly around this, so there will have been lots of social mixing. I can't yet say where the initial infection came from, how it's got into this cohort, and why it's created such an explosive amount of infections," she added.

As per Trish Mannes, UKHSA Regional Deputy Director for the South East, even after two doses, the MenB vaccine “does not protect against all strains of meningococcal disease, nor against all infections that can cause meningitis. It also does not prevent the bacteria from being carried and spread in the community”.

The UKHSA thus warned people to be aware of the signs and symptoms of invasive meningococcal disease, and to seek immediate medical attention if they or anyone they know develops these signs and symptoms.

Common symptoms include:

• rash
• sudden onset of high fever
• severe and worsening headache
• vomiting and diarrhea
• joint and muscle pain
• seizures.

Being tall can have its advantages, but a new genetic study linked height with significant health problems, such as a higher risk of developing heart disease and endometriosis throughout one's lifetime.

While genetics and environmental factors together influence a person’s height, the stature can also prove to be a risk factor for determining the risk of atrial fibrillation, which occurs when the heart quivers rapidly and erratically instead of beating regularly, said the researchers from the China Medical University Hospital in Taiwan.

“By integrating genetic data across multiple East Asian biobanks, we show that the genetics of stature is linked not only to growth-related traits but also to clinically relevant outcomes—most notably atrial fibrillation and endometriosis," said the team in the paper.

"These results suggest that stature-related polygenic scores could help improve early risk stratification in East Asian populations,” they added.

Also read: Woman Left Medically Infertile After Seven Surgeries For Endometriosis That She Did Not Have

Key Findings

The team led by Fuu-Jen Tsai conducted a large-scale genetic analysis on people of East Asian origin. They analyzed 120,000 Han Taiwanese individuals and compared them with 27,966 controls with familial short stature (FSS) -- a harmless condition where people are short due to inherited genetics -- to find genetic factors.

The study also linked a person’s height to overall body size and lung function, as well as cardiovascular traits and reproductive traits, including the age when menstruation starts.

Their findings, published in the journal PLOS Genetics, identified 293 genetic variants linked to height and five linked to familial short stature.

The genetic variants responsible for tall stature increased the risks of both atrial fibrillation and endometriosis. In comparison, the genetic factors for short statures offered a slight protection against endometriosis.

The results proved that taller stature increased the risk of atrial fibrillation independently. But the risk of endometriosis was determined through menarche/weight in taller people.

The Role Of Estrogen

A 2020 study from Denmark shares a possible explanation for the link between height and increased risk of atrial fibrillation: the rising estrogen levels.

Estrogen is a hormone known to promote the growth of the lining of the womb and is also believed to play a role in growth spurts during puberty.

The study, published in the Annals of Human Biology, showed that taller and slim girls in childhood had a high risk of developing endometriosis. The study also marked a lower body mass index as an increased risk of endometriosis.

However, further research is needed to validate these associations and inform clinical applications.

Early monitoring among younger populations has been the primary focus of the recently released American Heart Association (AHA) 2026 cholesterol guidelines.

The deliberate shift is reportedly based on new evidence about how heart disease develops over time.

Speaking exclusively to HealthandMe, Dr. Nils P Johnson, Professor of Cardiology, University of Texas, Houston, US, shared that atherosclerosis, or the buildup of plaque in arteries, doesn’t suddenly appear in middle age; it begins silently in youth.

That is why the AHA guidelines highlighted the importance of early screening.

“Cholesterol risk is really about long-term exposure. Just like years of breathing polluted air can damage your lungs, cholesterol builds up in the body over time. It’s not just about how high your levels are at one moment—it’s about how long you’ve lived with them. For example, one person might have very high cholesterol for 30–40 years, while another has moderately elevated levels for 60 years. Over time, their total exposure can be similar—and so can their risk," Dr. Johnson said.

What this means in practice is that treating cholesterol is about reducing total lifetime exposure.

The cardiologist explained that there are two ways to do that: lower cholesterol levels or start treatment earlier.

"Both approaches achieve the same goal—shrinking the overall ‘cholesterol burden’ by reducing how much cholesterol is in the body and how long a person is exposed to it,” the expert said.

The AHA 2026 Cholesterol Guidelines

As per the Global Burden of Disease Study 2021, the burden of heart failure in adolescents and young adults aged 10–24 years is increasing globally.

The guidelines call for early intervention through early screening and healthy lifestyle changes, starting from childhood.

It recommends:

• Children (9-11 years): Cholesterol screening if never done before.
• Adults (30-79 years): Evaluate 10- and 30-year ASCVD risk to determine the need for early intervention
• Considering lipid-lowering therapy for young adults with -- persistent LDL of at least 160 mg/dL, strong family history of ASCVD, and/or at least 10 percent 30-year risk for ASCVD

"They encourage us to think beyond the usual 5- or 10-year risk window and consider the long-term picture—what might happen 20 or 30 years down the road for someone in their 40s or 50s,” Dr. Johnson told HealthandMe.

Also read: ACC/AHA Cholesterol Guidelines 2026 Explained: Start Screening For Cardiovascular Diseases Early

Heart Disease: A Long-term Treatment

The heart expert also stated that chronic conditions like heart disease require long-term management—sometimes for decades—unlike an infection, where a two-week antibiotic course resolves the problem.

“One of the biggest challenges I see in clinics is that patients often come in after a dramatic event—chest pain, a heart attack, or a procedure. Alongside immediate treatment, I prescribe medications and recommend lifestyle changes. And then patients ask, ‘How long do I have to do this? This reflects a very different mindset”.

Dr. Johnson urged cardiologists and other healthcare workers to help patients understand, accept, and sustain these changes over the long term.

“Adjusting to the reality that life will be different for years or even a lifetime is not easy, but it’s essential,” he said.