Around March and April each year, most of Lao is shrouded in a toxic haze. In 2023, this haze pollution contributed to 2000 premature deaths in 2021. Exposure to air pollution inside people’s homes poses an even greater risk, contributing to an additional 7000 deaths yearly. Air pollution is one of the largest risks to public health globally. In Lao, outdoor air pollution is four times higher than global guidelines for human health and peaks during the crop-burning season in March and April.

How can we reduce this risk in Lao?

Multiple tools are available to tackle air pollution globally. Air quality monitors allow the concentration of air pollutants to be measured and record how they change over time and space. They are an essential component of air quality management. Still, monitoring networks are costly, and in many countries like Lao, resources need to be improved to establish and maintain an effective monitoring system.

Emission inventories can help overcome these challenges. Emission inventories are estimates of the air pollutants and greenhouse gases emitted in a defined region and time. Emissions can be estimated with existing activity data and standardized emission factors. For example, to estimate the emissions from the transport sector, take data on the average distance traveled by vehicles (e.g., the kilometers driven by cars in a year) and multiply by the amount of pollutant emitted per kilometer traveled (e.g., kilograms of particulate matter emitted per kilometer). Emission inventories quantify the magnitude of emissions and, importantly, allow the identification of key sources of pollutants. This information provides evidence for decision-makers when identifying and prioritizing mitigation actions.

Until recently, Lao PDR had no national air pollutant emission inventory. So, through a collaboration with the Ministry of Environment and Natural Resources, SEI researchers have helped develop the first national and subnational air pollutant and greenhouse gas emission inventory. The emission inventory was primarily developed using activity data from national statistics and covers all 18 provinces in Lao PDR. It includes emission estimates of all the major air pollutants important to human health and key greenhouse gases contributing to climate change.

The emission inventory identifies the key emission sources within Lao PDR. Significant sources include vegetation fires, household cooking, agriculture, electricity generation, and industry. Vegetation fires, specifically forest fires, are Lao’s largest contributor to air pollutants, accounting for 69% of fine particulate matter (PM2.5) emissions in 2019.

The benefit of quantifying emissions at the provincial scale means we can see how the magnitude and sources of emissions vary spatially. For example, emissions from agriculture, such as from rice production, and household cooking are higher in rural areas due to the large proportion of rural households cooking with wood and charcoal and the substantial land area used for crop and livestock production.

Saving lives and curbing climate change

The inventory also highlights the opportunity for co-benefits of reducing emissions for climate and air quality. Sources of air pollutants that are a risk to human health overlap with sources of greenhouse gases, which contribute to climate change. For example, electricity generation is the largest source of nitrogen oxides and carbon dioxide, impacting human health and climate.

The inventory also includes estimates of black carbon and methane, which are short-lived climate pollutants. Such pollutants can warm the atmosphere more than carbon dioxide and stay in the air for a shorter time. Black carbon directly impacts human health, while methane impacts health indirectly, contributing to ozone formation and affecting both human and crop health. Taking action to reduce black carbon and methane emissions could reduce the number of premature deaths in Lao PDR and contribute to achieving the Paris Agreement.

The emission inventory can also be used to project future emissions. The data can be used to evaluate different mitigation measures in terms of their potential to mitigate climate and health impacts simultaneously while also revealing any potential trade-offs.

A clearer future from Vang Vieng

In June 2023, representatives from various governmental departments assembled in Vang Vieng, Lao. The representatives were keen to enhance their understanding of the emission sources in Lao and explore mitigation measures to reduce emissions. SEI researchers at this meeting trained government officials on air quality planning and management as well as the use of the Low Emissions Analysis Platform (LEAP), a tool used globally for integrated energy, climate change mitigation, and air pollution abatement planning.

Building on the work at that meeting, the Ministry of Natural Resources and Environment plans to develop a National Clean Air Plan. The Lao emission inventory can help inform this plan, as well as provide an evidence base for integrated action on air pollution and climate change. Lao PDR still faces significant challenges to tackle air pollution, but the road ahead needs to be more modern.