Although rains have temporarily cleared the air across vast stretches of Southeast Asia, there are still concerns that hazardous smoke from Indonesian forest fires could continue to choke the people living in the region.

While the thick, dirty, white haze that has blanketed parts of Indonesia, Singapore, Malaysia and Thailand is not a new phenomenon, it has intensified this year due to the El Niño weather phenomenon, sickening hundreds of thousands, disrupting air travel and fueling anger at the Indonesian government.

The fires are usually man-made and caused by firms and smallholder farmers who engage in illegal slash-and-burn practices as a relatively inexpensive means to clear and prepare vast tracts of land in Indonesia's Sumatra and Kalimantan islands.

In mid-October, scientists from the Center for International Forestry Research (CIFOR) traveled to Palangkaraya, the provincial capital of Central Kalimantan Province, to see the situation with their own eyes. There, they carried out tests using the latest technology to assess the extent of the harmful impacts.

Verchot: 'The fires threaten critical habitat for endangered species like orangutan, sun bears and Sumatran tiger'

In a DW interview, Louis Verchot, Director of Forests and Environment Research at CIFOR, and one of the scientists who visited the affected areas, speaks about the impact the haze crisis is having on people and the environment, the measures taken by the authorities to tackle the issue, and why it is so difficult to put out the fires.

DW: How bad is Southeast Asia's current haze crisis?

Louis Verchot: The haze cloud extends from Manila in the Philippines to Bangkok in Thailand, so this is a regional crisis. Air quality is typically measured by an index called the pollutant standards index (PSI).

PSI values above 300 are considered hazardous, but in communities and cities in Central Kalimantan province, the pollution index reading has crossed 2,000 in recent weeks.

In what other ways are the fires affecting the environment?

The fires have a number of impacts on the environment; greenhouse gas emissions are one of them. Typically in El Niño years, we can see the impact of fires on CO2 levels in the atmosphere and this year will be no different.

At the moment we are making only very rough calculations because it is difficult to see the area that has been burned through the layer of smoke overlying the region.

But Guido van der Werf from the University of Amsterdam estimates that emissions are on the order of 1.6 billion tons of CO2. To put that in perspective, that is about 30 percent of the annual emissions of the USA or 180 percent of the annual emissions of Germany.

Another important environmental effect is the loss of productivity of dry-season cropping. Many farmers produce vegetables for cities and local consumption during the dry season using ground water for irrigation.

Because the sunlight intensity has decreased due to the smoke, these crops are not growing well - a development that threatens the livelihoods of these farmers.

The fires also threaten critical habitat for endangered species like orangutan, sun bears and Sumatran tiger. We hear from some conservation organizations that one-third of Indonesia's orangutans are threatened by the fires around Sebangau forest, which is home to around 7,000 of them.

The fires are usually caused by firms and smallholder farmers who engage in illegal slash-and-burn practices

What exactly is this haze made of?

We are still processing our data, but we know that the smoke - when emitted from the peat - contains carbon monoxide, methane, nitric oxide, cyanide, formaldehyde and other aldehydes, ammonia, particulates (PM10 and PM2.5), etc.

Over time, these gases react and produce other chemicals like ozone, which is toxic to plants and people. Although many of the gases' components are harmful, they are not necessarily deadly. But in high enough dosage they could be considered poisonous.

So I think we need to reconsider the use of the term haze, which to me conjures an image of a hazy summer day, where the sky is slightly obscured. This stuff is anything but that. The smoke is acrid and irritating. I would prefer to call it noxious smoke.

Given its hazardous nature, what impact are these gases having on people's health?

The health effects are quite severe, with local newspapers reporting of half a million cases of severe respiratory problems. This is probably an underestimate as only those most severely affected seek medical attention.

What measures has the Indonesian government taken to help people in the affected provinces?

The Indonesian government has been fighting the fires across the archipelago, and recently solicited support from other countries. At the moment, six nations have sent teams and equipment to help the Indonesians.

The authorities have been digging ditches in the peatlands to get access to water to fight the fires, but this practice is questionable. While digging a ditch certainly provides water, it also drains the water out of the soil profile and increases its flammability. It also sets the stage for repeated burning as areas that are drained burn more frequently.

So when a ditch is dug, adequate human resources and equipment need to be deployed to put the fire out. But this does not always happen. We saw a few fire crews while we were in the field near Palangka Raya and none was well equipped or staffed to face the challenge.

Beyond fighting the fires, the government is working to reinforce the healthcare system to better treat the victims of the smoke.

There are anecdotes daily in the newspapers here about overstretched health facilities that do not have the resources to care for those most affected by the smoke. Evacuations have begun in some areas and that should help particularly vulnerable people like children and the elderly.

Verchot: 'An important environmental effect of the fires is the loss of productivity of dry-season cropping'

How long will it take to put out the fires in these areas this year?

Peat fires are insidious. Peat is organic matter, which when dry is very flammable. Peat soils can be many meters thick. Fortunately, only the upper layers of the peat are dry and typically about 20 centimeters below the surface the peat is quite humid.

However, the fires spread underground through the root systems of trees that have been slashed or toppled.

This dries out the surrounding peat, which ignites and the fires spread. So you end up with slow-burning wet material and that is what gives off the smoke. You have to walk carefully across burned peat as it is very porous underneath and the surface easily collapses in some places under foot.

These fires will likely go out of their own accord once the rains begin. Over the past four days there has been some rain in Central Kalimantan and elsewhere, and the number of fires detected is slowly decreasing.

However, in El Niño years we often get a second burning season beginning in late January in other parts of the country. So even if the fires die down in the coming weeks, it is probably not finished.

What about the economic costs?

It is very early and very difficult to estimate. The Indonesian government is saying that costs so far amount to $47 billion, but we don't really understand how this was calculated. The 1997-1998 El Niño cost around $9 billion.

These are domestic figures, and one would need to account for damage in Singapore, Malaysia, the Philippines, and Thailand to get a proper figure. We will not know this with any precision for a while.

What long-term solutions are needed to effectively tackle this issue?

We say an ounce of prevention is worth a pound of cure. Here we are learning that the cure is beyond the reach of the government even with outside help. So while the priority at the moment is on public health and firefighting, measures need to be taken once the crisis is past to ensure that this situation does not repeat itself.

Indonesia is a very diverse country. The causes and the solutions will vary from island to island and province to province. The response is going to need both deterrence and incentives. So law enforcement will be part of the solution as well as subsidies and support to communities and landowners to achieve their aspirations with different means. Better monitoring is also going to be required.

'The fires spread underground through the root systems of trees that have been slashed or toppled'

To definitively solve the problem, the solution may be quite radical and entail removing communities and industries from peatland areas.

These peatlands will need to be restored and we are not sure how to do that at the moment. We believe we can accomplish a lot by blocking the drainage canals so these lands can be flooded again. But we do not know just how much ecological or hydrological recovery is possible.

If Indonesia goes down this path, the local scientific community will need to play an important role and support the technical agencies to learn lessons quickly and implement restoration efficiently.

Louis Verchot is Director of Forests and Environment Research at the Center for International Forestry Research (CIFOR).