Look at satellite images from Southeast Asia this week and you will see large areas of Indonesia, Malaysia and Singapore blanketed by dense plumes of smoke. These smoke plumes have severely degraded ground-level air quality.
Extreme air pollution has caused Malaysia to declare a state of emergency and Singapore to embark upon strained dialogue with Indonesia about its responsibilities.
Forest destruction, carbon and biodiversity
The fires are set purposely to convert rainforest into land that can be used for agriculture and plantations, mostly for palm oil production. Maps show that many fires escape control into surrounding forests and plantations.
Research from United Nations University shows that collectively, these fires are destroying a global hot spot of tropical biodiversity.
The fires also ignite peatlands, releasing enormous stores of carbon into the atmosphere. For example, the fires in Borneo during 1997’s drought released the equivalent of 13-40% of the annual global carbon emissions from fossil fuels.
In the past, high levels of catastrophic fire activity in tropical rainforests have been associated with EL Niño induced droughts. But this year the region is not in the grip of a severe EL Niño drought, and yet the 2013 fires are shaping up to be among the biggest on record.
The widespread fires may signal a positive feedback between forest fragmentation and fires. As dense road networks and partially cleared forests are coupled with high temperatures and numerous human ignitions, we could be in a cycle where burning increases fragmentation and fragmentation increases burning.
Human health
The consequences of exposing densely populated regions to extreme concentrations of air pollutants are serious. The extreme regional haze from fires lit during the strong EL Niño drought of 1997-8 was associated with a 40% increase in mortality in Malaysia on days when the average concentration of smoke particles, at a size that can lodge deep in the lungs, exceeded 210 micrograms per m3. While there is no lower concentration of smoke related particles that is known to be safe for all people, in most Australian cities the daily average concentrations are around 20 micrograms per m3 and, in line with WHO guidelines, our daily average air quality standard is set at 50.
Research published in Environmental Health Perspectives showed that throughout Southeast Asia between September 1997 and August 1998, smoke pollution from forest fires was likely to have claimed around 296,000 lives. This is in marked contrast with the estimate of 43,000 smoke-related deaths during an equivalent time period (1999-2000) when strong wet La Niña conditions were associated with far fewer fires.
Human mortality is the tip of the iceberg. The evidence concerning the respiratory impacts of forest fire smoke - from worsening symptoms of asthma and chronic lung diseases to precipitating emergency hospital admissions - is clear, and evidence associating fire smoke pollution with other health impacts such as worsening heart diseases is emerging.
Whatever way health impacts are measured, the personal and economic costs of severe air pollution are substantial.
What needs to change?
Protecting large populations from protracted periods of poor air quality is extremely challenging. Smoke particles penetrate indoors easily, and indoor environments give little protection in the absence of air-conditioning.
According to research published in the Journal of Exposure Science and Environmental Epedemiology, high-efficiency particle air filters can considerably reduce indoor concentrations of particulate matter, but this technology is not an option for many poorer people who live in rural areas across Southeast Asia.
Public refuges with filtered air conditioners can provide relief for particularly susceptible people, but again there is limited capacity to provide this to the broader population. Masks are a common response during these events. But to work, masks need to be designed specifically to exclude smoke, fit tested and used continually during exposure. This is only really practical in short-term occupational settings.
Preventing deforestation fires is the most effective way to avoid these disasters. But the social and economic drivers are running counter to this. There are schemes such REDD+ that can pay local communities to conserve forests and store carbon but they are not obviously slowing deforestation in South East Asia. A quantum leap in funding from the developed world would be required to do so.
Fires in tropical rainforest areas rarely occur in nature and the current rash of fires have been set to convert land from rainforest to agriculture - undertaking this land conversion mechanically, without using fire, is not a realistic option. The graphic smoke pollution is a visible symptom of an ecological collapse of one of the most biologically diverse regions on Earth.