Around seven million premature deaths annually are attributed to air pollution – one in eight premature deaths globally.

A significant proportion of these deaths occur in developing cities where air pollution levels are high and growing rapidly. Indeed, only 12% of cities worldwide achieve World Health Organization (WHO) guideline levels for air pollution – and some cities suffer from air pollution levels that are as much as 10 times, or more, above the guideline limits.

Already, more than half of the world’s population lives in cities. By 2050, the world’s urban population will double in size, and most of that growth will occur in low and middle-income cities.  Acting to control urban air pollution is therefore an urgent health issue.  By reducing urban air pollution levels, cities and countries can reduce the burden of disease from stroke, heart disease, lung cancer, and both chronic and acute respiratory diseases, including asthma.

Urban air pollution is also a critical climate issue.  Short-lived climate pollutants such as black carbon and methane are main contributors to health-harmful air pollution. These SLCPs have a short lifespan in the atmosphere, meaning that harmful concentrations of SLCPs can be reduced in a matter of weeks to years, resulting in near-term climate benefits as well as health benefits from improved air quality.

There are a range of affordable technologies, investment strategies and policy options that municipalities can choose to significantly reduce short-lived climate pollutants. These involve land use/spatial planning, transport, building efficiencies, energy production and waste management. Many of these same strategies, such as planning infrastructures for mass transit or non-motorized transport, also reduce long-lived CO2 – and support better health in other dimensions such as physical activity and traffic safety. This is why fast action now in cities can save lives today as well as reducing the impact of climate change on the next generation.  

Top facts

Over half the world’s population live in urban areas yet only 12% of cities worldwide achieve WHO guidelines for air pollution.
Globally, one in eight premature death is caused by air pollution, amounting up to ~7 million premature deaths annually.
By reducing air pollution levels, cities and countries can reduce the burden of disease from stroke, heart disease, lung cancer, and respiratory diseases for more than half the world’s population.



The initiative’s mission is to help empower cities to take effective action on air quality, in collaboration with health, environment and development sectors.

The CCAC initiative is led by WHO, UNEP, the World Bank, governments of Norway and the United States, as well as urban and civil society stakeholders, such as ICLEI (International Council for Local Environmental Initiatives) and ICIMOD (the International Centre for Integrated Mountain Development). Working through our respective organizations and agencies, we aim to harness the energies of existing sustainability initiatives, focusing on synergies among health, air quality and environment, and development leaders.  Traditional practitioners will play a particularly important role in reaching high-risk and vulnerable populations.

The initiative will link with other related CCAC initiatives such as those promoting cleaner heavy-duty diesel vehicles, better management of municipal solid waste, and cleaner brick production and domestic cookstoves to improve people’s health in the near-term and for future generations.  Lessons learned in urban areas will be used to support action in rural areas.


Initiative contacts

Sandra Cavalieri
Sandra.Cavalieri [at] un.org

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What are health risks associated with air pollution?

Air pollution is responsible for an estimated 7 million deaths annually, or one in eight premature
deaths every year. This makes it the world’s largest environmental health risk, and among the largest
global health risks – comparable with “traditional” health risks such as smoking, high cholesterol, high
blood sugar and obesity.

Some 4.3 million air pollution-related deaths are due to household air pollution and 3.7 million
deaths are due to outdoor air pollution. Most air pollution-related deaths are from heart disease and
stroke, followed by chronic obstructive pulmonary disease, acute and chronic respiratory conditions and cancers.

The air pollutant linked most closely to excess death and disease is PM2.5 (particulate matter less
than 2.5 micrometres in diameter), heavily emitted by both diesel vehicles and the combustion of biomass, coal and kerosene. Ozone is another pollutant that causes significant respiratory illness, including chronic asthma. There is growing evidence that oxides of nitrogen (NOx), a major contributor to ozone and heavily emitted by diesel vehicles, is also linked to significant health risks.

What is the link between air pollution and climate?

Black Carbon is a short-lived climate pollutant that is a major component of health-harmful PM2.5 air pollution – particularly from diesel vehicles, diesel engines, coal and biomass stoves and waste incineration. Since black carbon persists for only a short time in the atmosphere, reducing black carbon emissions can have significant near-term climate and health benefits.

Ground-level Ozone is also an SLCP, formed by a mix of air pollutants typically emitted over cities or nearby rural areas, including methane (another SLCP) from urban sewage, waste, and agriculture,as well as NOx from vehicles. Along with being a key factor in respiratory illness, ozone decreases crop yields and contributes to climate change.

Why is it important to take immediate action to reduce short-lived climate pollutants?

By acting now to reduce short-lived climate pollutants that are also air pollutants we will see substantial and immediate gains in public health, saving millions of lives, as well as slowing near-term climate change. The United Nations Environment Programme and the World Meteorological Organization have estimated that reducing SLCP emissions from key sources such as traffic, cookstoves, waste, agriculture and industry could reduce global warming by about 0.5° C (2010-2050).

Public health benefits are enjoyed locally – The largest initial benefits of reductions in short-lived climate and air pollution emissions will be enjoyed by people living in the areas where actions are taken – making measures very attractive to policymakers. Public health benefits of reduced ozone and black carbon emissions may begin to be realized within in a matter of days or weeks through improved air quality.

What groups are most affected by air pollution and its impact?

Air and climate pollutants have their greatest health impacts among the poor – but the poor are not the only victims of air pollution. Reducing household pollution risks from smoky biomass and coal cookstoves, in particular, can help alleviate the burden of poverty-related diseases. Urban air pollution levels also tend to be higher in many low-and middle-income cities and in poor neighbourhoods of high-income cities. This means reductions in SLCPs can have particularly large health benefits for lower income groups as well as for children, elderly, and women.

It is important to remember, however, that urban air pollution disperses very widely. Ozone pollution levels may often be highest on the urban periphery. So rich and poor alike benefit when SLCP emissions, and consequent air pollution, are reduced.

Why is it critical to address SLCPs in urban areas?

Urgent action to tackle air pollution in cities is needed to improve the health and well-being of over half of the world’s population. Only 12% of cities globally meet WHO air quality guidelines, with some cities suffering from pollution levels 2-5 higher than guideline thresholds. The good news is that urban planning, urban transport, building design and waste methane gas capture can reduce urban emissions from traffic, building energy, power systems and municipal sewage/waste.

Strategic changes in urban development priorities may be the most effective means of reducing reduce air and climate pollutants while optimizing health benefits. Cities are suffering from soaring rates of noncommunicable diseases. This is due not only to air pollution, but also to physical inactivity, poor diets, unsafe housing and other urban health inequities. Urban policies that target climate and air pollution emissions, as well as other causes of ill health, can yield multiple benefits. For instance, investing in clean urban transit, pedestrian and bike networks can help reduce traffic injury and support physical activity – as well as reducing SCLPs, air pollution and CO2 emissions. More physical activity, in turn, helps reduce obesity and obesity related-diseases.


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