The air is only deteriorating by the day and is affecting our health adversely.

However, exposure to air pollution--particularly smog--does not lead to respiratory diseases only. A new report, released by UNICEF (United Nations International Children's Emergency Fund) has revealed glaring details about how it also impacts a child's brain development.

According to the report that was released a day after the first International Smog Day (December 5), a majority of South Asian babies, under the age of one, face the risk of poor brain development due to air pollution.

This is what the report unveiled:

1. Air pollution is associated with some of the biggest killers of children, such as pneumonia, which is responsible for the deaths of 920,000 children, under 5 years of age, every year.

2. Air pollution is also linked with asthma, bronchitis and other respiratory infections and diseases, which can be debilitating, force children to miss school and even cause long-lasting damage to their health and well-being.

3. Scientific research has also pointed out a potential new risk that air pollution poses to children's lives and futures--its impact on their developing brains.

4. The first 1000 days of a child's life are crucial. That's when the brain undergoes the most critical and rapid growth. Every neural connection, made during this critical window of brain development in early childhood, forms the foundation for future neural connections and ultimately influences the likelihood of healthy development of a child's brain.

According to the new UNICEF analysis, nearly 17 million babies live in areas where outdoor air pollution is at least six times higher than international limits, potentially putting their brain development at risk, simply because of the air they breathe. The vast majority of these babies--over 12 million--are in South Asia.

How does air pollution affect brain development?

Air pollution potentially affects children's brains through several mechanisms. First, particulate matter can cause neuro-inflammation by damaging the blood-brain barrier, a thin, delicate membrane that protects the brain from toxic substances.Ultra-fine pollution particles (particulate matter that is equal or less than 2.5 microns in diameter) pose an especially high risk because they can enter the blood stream more easily and travel through the body to the brain.

In older people, the breakdown of the blood-brain barrier has been strongly linked with Alzheimer's and Parkinson's disease. The dosage of toxic chemicals required to damage the growing brain in the first stages of life is much lower than what would cause damage to an adult brain.

Second, specific air pollution particles, such as magnetite, are so small that they can enter the body through the olfactory nerve and the gut. Magnetite is very common in urban outdoor air pollution, and a recent study found that it was considerably more present in brains of people living in areas where urban air pollution is high. Magnetite nanoparticles are highly toxic to the brain due to their magnetic charge and their ability to help create oxidative stress, which is often the cause of neurodegenerative diseases.

Third, several studies also show that polycyclic aromatic hydrocarbons (PAHs), a specific class of pollutants formed from fossil fuel combustion and commonly found in areas of high automobile traffic, contribute to a loss of or damage to white matter in the brain.

White matter contains nerve fibers that are critical in helping neurons communicate across different parts of the brain. As children grow and experience the world around them, well-functioning neural connections provide the foundation for continued learning and development.