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.

Delhi's AQI on Tuesday morning seemed to be doing somewhat better than Monday morning. The AQI has brought some relief to the residents who had been dealing with 'severe' pollution levels, with visibility being hit. As per Tuesday's AQI, according to Central Pollution Control Board (CPCB), Delhi's air pollution stood at 381 AQI as of 6.30 am. This has placed the air quality in the 'very poor' category.

While it has become a habit of many to check AQI before stepping out of the house, how many of us actually understand what AQI really means?

Recently, Delhi's Chief Minister Rekha Gupta claimed that AQI and temperature are the same. At a summit hosted by a news channel, Delhi CM Gupta referred to AQI as "temperature".

Such statements could further lead to misconceptions, and add to everyday confusions. Health and Me is breaking down what AQI really means and why is it not the same as temperature.

How Air Quality Index Work And What It Means

As the Delhi CM claimed that AQI is like temperature and could be "measured using any instrument", is not true. Though it is understandable why such comparisons may have been drawn as you can easily check the AQI report on your phones, like we do with temperature.

However, in real sense, AQI or the air quality index is a tool used for communicating outdoor air quality and health. The AQI includes six-color coded categories, each of which corresponds to a range of index values. The higher the AQI value, the greater the level of air pollution and the greater the health concern.

Air quality is made of dust and small particles like PM2.5 and PM10, along with gases like nitrogen dioxide from car exhaust, sulphur dioxide from factories, and carbon monoxide from vehicles. The levels are measured through specialized machines. In India, the standard of the machines are carried out by the Central Pollution Control Board or CPCB.

What Makes Delhi So Polluted?

As per a review of Delhi's air quality from 1990 to 2022, published in Sustainability (MDPI), an open access journal, these are the following sources of Delhi's Air Pollution:

• Transports emit around 10 to 30% of pollution. This includes all road, rail, and aviation modes and combustion of petrol, diesel, and gas.

• Dust make up another 10 to 30% of pollution. Dust from resuspension on the roads and construction activities.

• All industries, including small, medium, and large industries, including power plants and brick kilns lead to 10 to 30% of pollution.

• In summers, all residential activities, including cooking, lighting, and heating activities lead to 10% of pollution, whereas in winter, it makes up for 30%.

• Waste burning, including residential sides and landfills leads to 5 to 15% of pollution.

Power plants from outside the city leads to less than 7% of pollution. Dust storms contribute to less than 5% of pollution. Agricultural residue burning, which is a seasonal source of pollution leads to less than 3% of pollution, whereas firecrackers, another seasonal source, leads to less than 1% of pollution.

Earlier in November, the Public Health Ontario's (PHO) data revealed that Ontario and Canada as a whole could be in a "very tough" flu season this year, thanks to the Influenza A or the flu A. The PHO data revealed a 1.8% rise in influenza cases in the last week of October. Now, amid the influenza A outbreak, 3 children have died from the same in Ottawa and Eastern Ontario region.

Influenza A: Can Flu Kill People?

As per the infectious physician at the Johns Hopkins University Center for Health Security, as reported in Scientific American, "Dying from the flu is not like dying from a bullet or a black widow spider bite. The presence of the virus itself isn't going to be what kills you. An infectious disease always has a complex interaction with its host.”

Once the virus enters someone's body usually via their eyes, nose, or mouth, the influenza virus begins hijacking human cells in the nose and throat to make copies of itself. This triggers a strong response from the immune system, and sends battalions of white blood cells, antibodies and inflammatory molecules to eliminate the threat.

T cells work by targeting and destroying virus-infected tissue, especially in the respiratory tract and lungs where the infection usually settles. In most healthy adults, this response clears the virus and leads to recovery within days or weeks. In some cases, however, the immune reaction becomes excessive, damaging large areas of lung tissue and impairing oxygen delivery to the blood, which can cause hypoxia and, in severe cases, death.

What Is Influenza A?

As per the National Institutes of Health, US, influenza viruses that contains single-stranded RNA that are classified into three types: A, B, and C. Type A and B cause annual epidemics and even pandemics, while type C is a less common disease.

As per the Centers for Disease Control and Prevention (CDC), Influenza A viruses are descendants of the 2009 H1N1 pandemic virus that emerged in the spring of 2009 and caused a flu pandemic. These viruses, scientifically called the "A(H1N1)pdm09 virus," and more generally called "2009 H1N1," have continued to circulate seasonally since 2009 and have undergone genetic and antigenic changes.

Influenza A(H3N2) viruses also change genetically and antigenically. Influenza A(H3N2) viruses have formed many separate, genetically different clades in recent years that continue to co-circulate.

It is a fast-spreading respiratory virus responsible for seasonal flu outbreaks and, at times, global pandemics. It changes quickly through genetic shifts, which makes new strains harder to predict and control. The virus is grouped based on surface proteins called hemagglutinin and neuraminidase, with H1N1 and H3N2 among the most common strains in circulation. It spreads mainly through coughs, sneezes, or close contact and often comes on suddenly, causing fever, cough, body pain, and extreme tiredness. In some cases, it can lead to serious complications, especially in vulnerable groups.

Influenza A: Common Signs And Symptoms

• Fever or chills
• Dry cough
• Sore throat
• Headache
• Fatigue
• Some people could also get symptoms like diarrhea or vomiting, especially kids.

The symptoms usually appear 1 to 4 days after exposure and could linger for a week.

Hemoglobin is a key protein found in red blood cells. Its main job is to carry oxygen from your lungs to the rest of your body. When hemoglobin levels drop, the body may not receive enough oxygen to function well. Low hemoglobin can happen for several reasons, including health conditions, blood loss, or gaps in nutrition.

What Is Low Hemoglobin?

Hemoglobin is the oxygen-carrying protein in red blood cells. Adequate hemoglobin levels are essential for keeping organs and tissues properly supplied with oxygen. Without enough of it, the body begins to struggle to meet its basic energy needs.

Low hemoglobin is usually identified through a blood test. It is most often measured as part of a complete blood count (CBC), which checks different components of the blood, including red and white blood cells and platelets, as per Healthline.

While exact reference ranges can vary slightly between laboratories, healthy adult hemoglobin levels usually fall within the ranges listed below. These values are different for babies, children, and teenagers.

Normal Hemoglobin Count in Grams per Deciliter (g/dL) | Normal Hemoglobin Count in Grams per Liter (g/L)

Adult Males: 13.8–17.2 | 138–172

Adult Females: 12.1–15.1 | 121–151

Any reading below these ranges in adults is considered low hemoglobin and suggests that oxygen delivery in the body may be reduced, as per Mayo Clinic.

Is Low Hemoglobin Ever Dangerous?

Low hemoglobin is not always an emergency. In many cases, it develops gradually and can be managed with treatment. That said, very low levels can be dangerous. A hemoglobin level below 5.0 g/dL has been linked to serious complications, including heart failure and even death. Levels under 6.5 g/dL may be considered life-threatening and require urgent medical care.

What Causes Low Hemoglobin?

One of the most common reasons for low hemoglobin is anemia. Anemia occurs when the body does not have enough healthy red blood cells. The most frequent type is iron-deficiency anemia, which develops when the body lacks enough iron to produce hemoglobin.⁵

Other forms of anemia include pernicious anemia, which occurs when the body cannot properly absorb vitamin B12, and hemolytic anemia, where red blood cells are destroyed faster than they are produced.¹

Low hemoglobin can also be caused by:

• Blood loss or internal bleeding
• Certain cancers, including leukemia, lymphoma, multiple myeloma, and cancers that spread to the bone marrow
• Chronic kidney disease
• Deficiencies of folate or vitamin B12
• Hypothyroidism
• Liver disease
• Poor nutrition or malnutrition
• Myelodysplastic syndrome (MDS)
• Sarcoidosis
• Sickle cell disease and other inherited blood disorders
• Systemic lupus erythematosus
• Thalassemia, a genetic condition that reduces hemoglobin production
• Excess fluid in the body
• Cancer treatments such as chemotherapy and radiation can also lower hemoglobin levels, particularly in adults over the age of 65.

What Does Having Low Hemoglobin Feel Like?

Some people with mildly low hemoglobin may not notice any symptoms at first. Others may begin to feel unwell as levels drop further or remain low over time.

Common signs and symptoms include:

• Feeling dizzy or lightheaded, sometimes fainting
• Muscle weakness
• Ongoing fatigue or low energy
• Pale or washed-out skin
• Frequent headaches

How Is Low Hemoglobin Treated?

Treatment depends entirely on what is causing the low hemoglobin. A healthcare provider will first identify the underlying reason before recommending treatment.

Possible treatment options include:

Blood transfusion: If hemoglobin is low due to heavy blood loss, a transfusion may be needed to restore levels quickly.

Vitamin supplements: When nutritional deficiencies are the cause, iron, folate, or vitamin B12 supplements are often prescribed. Hemoglobin levels usually begin to improve within six to eight weeks.

Intravenous (IV) therapy: In cases where iron or B12 levels need to be raised rapidly, IV infusions may be recommended.

Bone marrow transplant: This may be required when low hemoglobin is linked to certain cancers or bone marrow disorders.

If a long-term illness is responsible, managing that condition becomes the key part of treatment, alongside monitoring hemoglobin levels regularly.