A recent study published in the journal Nature, shows a strong link between El Nino and increased air pollution in Indonesia to the Philippines, Vietnam, and Thailand. This is because during an El Nino, rainfall is typically lighter than normal in that part of the world. Farmers in the region thus increase the use of fire to burn and clear the land for agriculture in El Nino years. The additional pollution is believed to be responsible for as many as 15,000 fatalities in El Nino years.
The study which was conducted jointly by Columbia University and NASA’s Goddard Institute for Space Studies used emissions estimates taken from satellite measurements from 1997 to 2006. They fed the data into atmospheric chemistry models to plot out air pollution for the region.
For example during the strong El Nino of 1997, their analysis showed that there was a jump in the amount of fine particles in the atmosphere exceeding World Health Organization standards by 300% for at least 200 days of the year. Ozone levels, a component of smog, also increased substantially. In comparison, during the La Nina episode in 2000, the level of carbon particulates was 98% lower than in 1997. La Nina provides enhanced rainfall for Indonesia and southeast Asia.
The region is home to over half a billion people. Furthermore the researchers found that even though most of the burning occurs in rural areas such as Sumatra and Bornea, the impacts are great even well away in large cities such as Singapore and Kuala Lumpur. Carbon particulates are of most concern, as the are linked to heart disease. The study concludes of the 15,000 deaths contributed to this fire pollution in El Nino years, around 10,000 would come from carbon exposure, with the ozone responsible for as many as 5,000. Smog, containing oz0ne is hard on the respiratory system, especially for those with pre-existing conditions.