Seven million people die from air pollution every year. It has been linked to an increased risk of dementia. What is it, how does it work, and what is being done to reduce it?

Is air pollution the same as climate crisis?:  No. When people talk about climate crisis, they are talking about the effects of rising temperatures on the Earth's climate - its seasons, weather patterns, natural disasters, and so on. Air pollution is about the quality of air that we breathe.

What is causing it? This is where climate crisis and air pollution are closely related. The things that cause one often contribute to the other.

For example, burning wood or fossil fuels does not just release greenhouses gases that lead to global warming - it also releases particulates into the air. These are tiny particles that get stuck in your lungs and damage your health.

Many greenhouse gases are also toxic to breathe in large amounts. Take diesel cars: for a long time, they were thought to be cleaner than petrol, but recent studies have found that they release much higher amounts of nitrogen oxides. At high concentrations, these can inflame airways and cause breathing problems. They also react with the sunlight to form smogA kind of toxic fog caused by high levels of air pollution..

So, air pollution is pretty bad for us? That is putting it mildly. In 2018, a study in the British Medical Journal linked air pollution to dementiaA syndrome associated with memory loss and other declining brain functions. . Although it did not establish a direct cause, it found that people over the age of 50 in London were 40% more likely to get dementia if they lived in an area with high levels of nitrogen oxide.

What's more, in 2017, a global report on air pollution from The Lancet Commission on Pollution and Health said that it kills 7.4 million people per year, costs trillions of dollars, and "threatens the continuing survival of human societies".

Deaths from all forms of pollution come to around nine million per year, easily outstripping those from tobacco smoking, AIDsAcute Immune Deficiency Syndrome. It interferes with the immune system, leaving sufferers more vulnerable to common diseases. Around the world, almost 40 million people are believed to be living with the disease., and malariaA serious parasite infection transmitted by mosquito bites. It is one of the world's most lethal diseases..

Yikes. Who is most at risk? Poor countries suffer the highest levels of air pollution - and the most deaths. This is not just a human tragedy, it also slows down the growth of those countries. And severe air pollution makes everyday life more difficult. Last year, in Delhi, the smog was so thick that five million children were told to stay home from school, flights were cancelled, and factories temporarily closed.

But air pollution affects everyone, rich and poor. In London, one of the developed world's wealthiest cities, around 40,000 deaths are linked to air pollution each year.

How does air pollution kill people? This is where it gets a bit complicated. No death certificate lists "air pollution" as the cause. Instead, it contributes to an overall decline in a population's health. That figure does not mean that 40,000 Londoners are killed by dirty air, and everyone else is fine. The whole city is affected by it.

The health problems of vulnerable people are made particularly worse, but other factors can also contribute to their deaths.

So, while the damage caused by particulates in London is equivalent to 29,000 deaths, it is more accurate to say it led to "340,000 years of life lost".

What is being done? Luckily, many of the policies being introduced to tackle climate crisis, such as converting to renewableEnergy sources, such as wind and solar power. energies, will also help to clean the air.

Meanwhile, many countries are rolling out specific air pollution policies. In 2017, the government announced that it would be raising existing taxes on diesel cars and investing 220 million in a clean air fund. London, Bristol and Oxford are both hoping to ban polluting cars from certain areas in the next 10 years.

Is it enough? Only time will tell - although the head of policy at the Chartered Institute of Environmental Health called the clean air fund's 220 million a "drop in the ocean".