The updated estimates suggest that around 7 million people every year are dying because of exposure to fine particles caused by burning non-clean fuels for cooking, public transport, industry and motor vehicles.
These fine particles can penetrate deep into the lungs and cardiovascular system and as a result can cause many diseases including stroke, heart disease, lung cancer, chronic obstructive pulmonary diseases and respiratory infections including pneumonia.
"Air pollution threatens us all, but the poorest and most marginalized people bear the brunt of the burden," says Dr Tedros Adhanom Ghebreyesus, Director-General of WHO.
"It is unacceptable that over 3 billion people – most of them women and children – are still breathing deadly smoke every day from using polluting stoves and fuels in their homes. If we don't take urgent action on air pollution, we will never come close to achieving sustainable development."
While much of the discussion around air pollution has been focused on developed nations and cities, more than 90% of air pollution-related deaths occur in low-and middle-income countries, mainly in Asia and Africa.
This is exacerbated by the fact that around 3 billion people (more than 40% of the world's population) doesn't have access to clean cooking fuels, the main cause of indoor air pollution around the world.
While access to cleaner cooking technologies is improving, the WHO reports that this access is not keeping pace with population growth, particularly in sub-Saharan Africa.
The WHO findings do show that there is change, albeit slow change.
More than 4300 cities spanning 108 countries are now included in WHO's ambient air quality database. Through this transparency and growing political interest in the subject there are some clear examples where countries and cities are trying to make a difference.
The WHO points out that India's Pradhan Mantri Ujjwala Yojana Scheme has given some 37 million women living below the poverty line free access to LPG connections so they can convert to clean household energy use.
Elsewhere countries around the world are starting to make firm commitments on the banning of heavily polluting vehicles in urban centres. Mexico City will ban soot-emitting busses and has also set a ban on all private diesel vehicles by 2025.
Here in the UK, it's believed that around 40,000 deaths every year can be made attributable to exposure to outdoor air pollution.
Many of the UK's cities also have air quality levels that far exceed the safe guidelines set out by the World Health Organisation. London broke its annual air quality guidelines in a single month this year, beating 2017 when the city broke its limits within just five days.
To try and tackle the air pollution crisis that's currently facing the capital, London Mayor Sadiq Khan has introduced a number of tough new measures including the T-charge which charges the most polluting types of car that wish to drive through the city.
Commenting on the WHO figures, Simon Gillespie, Chief Executive at the British Heart Foundation believes that while admirable, the UK government has much more to do.
"These figures from the World Health Organisation (WHO) show that as a country we still have a long way to go in the fight against air pollution, with several UK cities exceeding the air quality standards needed to protect health." he said.
"We know there is a strong link between poor air quality and heart health with almost six in ten global deaths (58%) related to outdoor air pollution caused by a heart attack or stroke. Our research has shown that air pollution, particularly from small particles in diesel fumes, increases the risk of these potentially deadly occurrences therefore it's vital that the Government takes immediate action in order to tackle this urgent public health crisis."