Human activities and natural processes produce many airborne pollutants that are harmful to our health or the environment. These can be solid particles, drops of liquid or gases.
The main natural sources of air pollution are wildfires and volcanic eruptions, which produce smoke, dust and ash containing hazardous substances.
Airborne pollutants such as sooty particles, low-level ozone, and sulfur and nitrous oxides can contribute to lung cancer, cardiovascular illnesses, asthma, bronchitis and other respiratory disorders.
Air pollution is especially bad in cities with heavy industry or large numbers of cars.
Globally, outdoor air pollution causes as many as one million early deaths, according to the World Health Organization.
In 2009, the Times of India reported on research by India’s National Allergy Asthma-Bronchitis Institute. It showed that half of non-smokers in Kolkata had lung disease that would normally be found only in heavy smokers, and said outdoor air pollution was largely to blame.
The problem is not confined to developing nations. A 2010 report by a UK parliamentary committee concluded that air pollution may cause up to 50,000 premature deaths in the country each year.
Forest fires that occur naturally or are started on purpose (such as to clear land) can create vast amounts of airborne pollution that travels long distances. In dry conditions, such fires can burn widely, triggering dense “haze” that can cause regional health and transportation problems.
Air pollutants with high nitrogen content could also lead to eutrophication or harmful algal blooms in nearby bodies of water.
Carbon dioxide and other greenhouse gases that contribute to climate change are also a form of air pollution.
ALTERNATIVES / SOLUTIONS
People can do little to protect themselves from air pollution so government action is needed to control pollutants. The World Health Organization says stricter controls on air pollution could reduce deaths in cities by 15 percent.
Many countries have set emissions standards to limit the amount of pollution from industry and/or cars but these vary greatly between countries are not always monitored and enforced effectively.
Efforts to address the health effects of air pollution caused by burning fossil fuels will also help to limit climate change.
REPORTING TIPS AND FURTHER READINGS
The World Health Organization has a large collection of information that can help journalists who are reporting on outdoor air pollution.
Another useful source is the Air Pollution and Climate Secretariat, an alliance of four Swedish environmental organizations.
CASE STUDY – Haze in Southeast Asia
Large areas of Southeast Asia are periodically stricken with an intense form of air pollution known as haze, which is caused by soot, dust, smoke and other particles.
Haze can be so severe that it drastically restricts visibility at ground level and can trigger a variety of respiratory illnesses.
Haze was particularly bad in 1997 when rampant burning in Indonesian forests led to a haze cloud that extended across much of Southeast Asia (as shown in this satellite image).
The 1997 haze led to direct economics costs of billions of dollars and prompted the Association of South-East Asian Nations (ASEAN) to agree a Regional Haze Action Plan.
In 2002 they signed an Agreement on Transboundary Haze Pollution but Indonesia – the source of many of the forest fires – did not sign it.
This has caused international tensions when fires in Indonesia led to haze in other countries such as Malaysia and Singapore.
At one point during 2006 there were at least 500 fires burning every day in the Indonesian province of West Kalimantan, according to the UN Office for the Coordination of Humanitarian Affairs.
In the provincial capital Pontianak the air pollution index reached 913. An index of 101-200 is considered ‘unhealthy’ while 300-550 is ‘dangerous’.