Applause broke out in Committee A at the World Health Assembly last month as representatives from health ministries around the globe agreed a historic resolution to address the health impacts of air pollution.
Spontaneous applause of this kind is a rare event in the generally rather formal proceedings at the Health Assembly. But this was a momentous event. The Health Assembly had never discussed this issue before. Conversations had been lengthy and complex. And for the first time governments had agreed a way forward to address the world's largest single environmental health risk: 1 in 8 deaths are linked to air pollution.
There are two types of air pollution. Both can be deadly. Every year, 3.7 million deaths are attributable to outdoor air pollution, and 4.3 million people die as a result of exposure to indoor air pollution.
Last year, WHO revealed that air quality in most of the world's cities that monitor outdoor air pollution fails to meet the Organization's guidelines for safe levels, putting people at additional risk of respiratory disease and other health problems. Only 12% of the people living in these cities reside in places where the air meets WHO air quality standards. About half of the urban population being monitored is exposed to air pollution that is at least 2.5 times higher than the levels WHO recommends.
In most cities where there is enough data to compare the situation today with previous years, air pollution is getting worse. There are many reasons for this - including reliance on fossil fuels such as coal fired power plants, dependence on private transport motor vehicles, and inefficient use of energy in buildings.
And the situation is even worse indoors. Nearly 3 billion people worldwide still lack access to clean fuels and technologies for cooking, heating and lighting. Women and young children are at particular risk, especially in lower-income countries where households still use kerosene and solid fuels - wood, crop waste, charcoal, coal and animal dung.
Around 6 in 10 of indoor- air-pollution related deaths are due to heart disease and stroke, but respiratory diseases are another major problem.
Hundreds of thousands of children die each year from pneumonia, because they breathe unhealthy air at home. WHO estimates that globally, more than 50% of pneumonia deaths among children under 5 are linked to household air pollution. Most of these deaths occur in lower income countries. But air pollution is also a problem in richer countries, where it is particularly associated with asthma.
For me, the impact of air pollution on children is the most poignant prompt to take action. When you see a child struggling to breathe because she has pneumonia or asthma, you realize how fragile life is and how easily it can be snuffed out. I still vividly recall how scared I felt as young doctor treating tiny Sudanese babies with pneumonia.
At WHO, we have produced a number of evidence-based recommendations to help countries reduce air pollution and improve people's health. But a recommendation can really only have impact if a government and its people embrace it - and commit to implement it.
That is why this new World Health Assembly resolution is so important. The world's governments have agreed to act.
One important step will be to develop air quality monitoring systems and health registries to improve surveillance so we have a better picture of who is being affected where. Another is to promote clean cooking, heating and lighting technologies and fuels. A third is to strengthen international transfer of expertise, technologies and scientific data in the field of air pollution.
At the same time, WHO will help countries build their own capacity to tackle air pollution and put together a new global plan to enhance health sector action.
This is an amazing moment. We are finally poised to act on what has been one of the world's most intransigent, and pernicious, health problems - and stop 8 million people, many of them very young children, dying every year because they breathe polluted air.