Over 12 million babies (under one year of age) live in areas of South Asia where outdoor pollution is six times higher than the international limit.

Another 5 million babies live in areas with similar levels of air pollution outside of South Asia. Globally, around 121 million babies live in areas where outdoor pollution levels are higher than international limits.

Air pollution is one of the biggest killers of children under five, being directly responsible every year for around 920,000 deaths from pneumonia.

Air pollution is also directly linked to incidences of other respiratory diseases such as bronchitis and asthma.

While these may not have as high a risk of death as does pneumonia, they are debilitating, often causing children to either miss school or under-perform at school, as well as contributing in long-term health and wellbeing impairments.

Air pollution is more likely to be bad in built-up areas such as cities and slums. In slum environments children are already facing multiple risks to their health such as inadequate sanitation, limited or no health care, lack of clean water and inadequate nutrition.

Adding air pollution to these risks greatly increases the chances that children's developing brains are adversely effected.

When the air carries with it small particles breathing these in causes neuro-inflammation. The thin membrane that protects the brain from toxic substances is damaged putting the brain at risk.

Very small particles (less than 2.5 microns in diameter) easily enter the blood stream and thus travel through the circulatory system to the brain, also challenging the integrity of the blood-brain membrane.

We know that in older people damage to this barrier is linked with Alzheimer's and Parkinson's diseases and we also know that children's brains are more vulnerable so lower levels of exposure are more dangerous.

In addition, even smaller particles (eg magnetite - a very common air pollutant in urban outdoor areas) can enter the body through the olfactory nerve and gut.

These particles are highly toxic as they carry a magnetic charge and contribute to oxidative stress which is in turn linked to neurodegenerative diseases.

Areas with high levels of car/truck traffic have high levels of hydrocarbons in the air and these are known to damage the white matter in the brain.

The nerve fibres children need to establish pathways in the brain to process information are contained in this white matter, so damage here impacts on the neural connections needed to continue to learn and develop.

Children living in areas where there are high levels of air pollution are found to have lower verbal and non-verbal IQ, less effective memory functioning, poorer school performance and behavioural challenges.

Air pollution impacts on the developing foetus in similar ways so that by age three, children exposed to air pollution in utero are likely to demonstrate developmental delay and later in childhood present with psychological and behavioural challenges (including ADHD, anxiety and depression).

Physical health is also affected.

Reducing air pollution is important. Reducing our dependence on fossil fuel combustion is a key step and this involves further investment in solar, wind and thermal sources of energy.

Public transportation systems can help reduce traffic levels. Parks, trees and green spaces help improve air quality.

Waste management, appropriate disposable and recycling systems for paper, plastics, metals and organics can help prevent the burning of harmful chemicals.

We need to think about how to reduce children's exposure to air pollution.

We need to think about the chemicals we use in the home (paints, cleaning products, cigarette smoke) as contaminants can enter the air through their use.

Where children are already vulnerable it is now possible to wear small monitoring devices that can identify levels of air pollution so that behaviour can be adjusted accordingly.

This is something we need to think about in Armidale, particularly in the winter.