Levels of air pollution have reached toxic levels particularly in some countries that the World Health Organization (WHO) said it has become one of the world's biggest public health issues.

Toxic fumes have reached levels so dangerous that the number of annual deaths caused by air pollution across the globe is now greater than those of Human Immunodeficiency Virus (HIV) and malaria combined.

The scientists warn that the number of fatalities could reach 6 million a year by 2050. The warning comes ahead of a new report showing the number of deaths caused by poor air quality.

"This is one of the biggest public health issues we have ever confronted," Dr. María Neira, WHO public health chief, said.

The predicament of toxic levels of air pollution or smog affects many of the world's major cities, from Kabul in Afghanistan to Hong Kong and Shijiazhuang in China. Even cities in Latin America are already affected. The increasing levels of toxic substances dispensed in the air cause a battery of respiratory and heart problems across the globe.

In late 2015, schools and offices were closed in China because of the toxic levels of smog that lasted for weeks. In December 2015, a blanket of thick gray smog covered skies in New Delhi, India. Tehran and Turkey also suffer tremendous levels of air pollution, especially during winter.

Exposure to air pollution has been linked to a surge in cardiovascular disease, around seven million premature deaths and respiratory diseases.

"It is an enormous cost not only in terms of mortality, but in terms of treating diseases and the costs of hospitalization - as most of these diseases are chronic. It will also lead to less working days and lower quality of life," Dr. Neira added.

The report to be released by the health agency on February was based on data collected from 2,000 world cities. It aims to raise awareness to the populations exposed to levels of air pollution beyond safe levels imposed by WHO.

Major pollutants in the air include particulate matter, carbon monoxide, ozone, nitrogen dioxide and sulphur oxide.

Dr. Neira added that the improvement of public transport systems, the increased number of energy-efficient houses and renewable energy can help lessen the detrimental effects of poor air quality. With joint commitment of both governments and citizens, air pollution issues and its consequent health effects can be addressed.

Photo: Simone Ramella | Flickr