World challenge to improve air quality

The World Health Organization (WHO) is today challenging governments around the world to improve air quality in their cities in order to protect people's health.

The call comes as WHO unveils its new Air Quality Guidelines with dramatically lower standards for levels of pollutants. WHO believes that reducing levels of one particular type of pollutant (known as PM10) could reduce deaths in polluted cities by as much as 15% every year. The Guidelines also substantially lower the recommended limits of ozone and sulphur dioxide.

The Air quality guidelines for the first time address all regions of the world and provide uniform targets for air quality. These targets are far tougher than the national standards currently applied in many parts of the world - and in some cities would mean reducing current pollution levels by more than three-fold.

Air pollution is estimated to cause approximately 2 million premature deaths worldwide per year. More than half of this burden is borne by people in developing countries. In many cities, the average annual levels of PM10 (the main source of which is the burning of fossil and other types of fuels) exceed 70 micrograms per cubic metre. The new Guidelines say that, to prevent ill health, those levels should be lower than 20 micrograms per cubic metre.

“By reducing particulate matter pollution from 70 to 20 micrograms per cubic metre as set out in the new Guidelines, we estimate that we can cut deaths by around 15%," said Dr Maria Neira, WHO Director of Public Health and the Environment. "By reducing air pollution levels, we can help countries to reduce the global burden of disease from respiratory infections, heart disease, and lung cancer which they otherwise would be facing. Moreover, action to reduce the direct impact of air pollution will also cut emissions of gases which contribute to climate change and provide other health benefits."

Given the increasing evidence of the health impact of air pollution, WHO revised its existing Air quality guidelines (AQGs) for Europe and expanded them to produce the first guidelines which are applicable worldwide. These global guidelines are based on the latest scientific evidence and set targets for air quality which would protect the large majority of individuals from the effects of air pollution on health.

“These new guidelines have been established after a worldwide consultation with more than 80 leading scientists and are based on review of thousands of recent studies from all regions of the world. As such, they present the most widely agreed and up-to-date assessment of health effects of air pollution, recommending targets for air quality at which the health risks are significantly reduced. We look forward to working with all countries to ensure these Guidelines become part of national law,” says Dr Roberto Bertollini, Director of the Special Programme for Health and Environment of WHO's Regional Office for Europe.

Many countries around the world do not have regulations on air pollution, which makes the control of this important risk factor for health virtually impossible. The national standards which do exist vary substantially, and do not ensure sufficient protection for human health. While the World Health Organization accepts the need for governments to set national standards according to their own particular circumstances, these guidelines indicate levels of pollution at which the risk to health is minimal. As such, the new WHO guidelines provide the basis for all countries to build their own air quality standards and policies supporting health with solid, scientific evidence.

Air pollution, in the form of particulate matter or sulfur dioxide, ozone or nitrogen dioxide, has a serious impact on health. For example, in the European Union, the smallest particulate matter alone (PM2.5) causes an estimated loss of statistical life expectancy of 8.6 months for the average European. While particulate matter is considered to be the main air pollution risk factor for human health, the new Guidelines also recommend a lower daily limit for ozone, reduced from 120 down to 100 micrograms per cubic metre. Achievement of such levels will be a challenge for many cities, especially in developing countries, and particularly those with numerous sunny days when ozone concentrations reach the highest levels, causing respiratory problems and asthma attacks.

For sulfur dioxide, the guideline level was reduced from 125 to 20 micrograms per cubic metre: experience has demonstrated that relatively simple actions can rapidly lower sulfur dioxide levels and directly result in lower rates of childhood death and disease. The guideline level for nitrogen dioxide remains unchanged; however, meeting these limits, which are essential to prevent the health consequences of exposure such as bronchitis, remains a great challenge in many areas where car traffic is intensive.

The guidelines propose progressive interim targets and provide milestones in achieving better air quality. “Building upon the work carried out for several years on air pollution, WHO has now set new targets which Member States can refer to in setting policy. The countries can measure their distance to these objectives, estimate the health impact of current pollution levels and benefit from health gains by reducing them,” says Dr. Michal Krzyzanowski, Regional Adviser for Air Quality, of the WHO Regional Office for Europe, coordinating the process of the Guidelines’ update from the WHO office in Bonn.