Studying the Contribution of Indoor Emissions to Outdoor Air Quality

E-sampler at a village in Nepal.
Photo: Parth Sarathi Mahapatra/ICIMOD

Particles of emissions produced by cook stoves are deposited on kitchen walls and ceilings, turning them black over time. This is a common sight in many villages in Nepal. This observation led a team supervised by Siva Praveen Puppala, an Atmosphere Initiative scientist at the International Centre for Integrated Mountain Development (ICIMOD) to conduct a study to better understand the contribution of indoor emissions to outdoor atmosphere. “Generally, when conducting studies, cook stoves are taken to a lab and their emissions measured directly. It is assumed that the emissions generated are released into the atmosphere when in truth some particles are trapped indoors,” says Puppala. He explains that the study intends to find out the amount or percentage of smoke that makes it out.  

Instruments installed next to a cook stove to measure emissions.
Photo: Sagar Adhikary/ICIMOD

The team used two sets of instruments to measure particulate matter (PM2.5), black carbon (BC), carbon dioxide (CO2), carbon monoxide (CO), and total volatile organic compounds (TVOCs). One was placed right next to a cook stove to measure the total emissions produced. The other set was installed at the most prominent smoke exit spot. “The most visible spots were selected to do the measurements,” confirms Sagar Adhikari, an emissions measurement research associate at ICIMOD. 

Measuring emissions escaping a house.
Photo: Parth Sarathi Mahapatra/ICIMOD

The percentage of emissions going out into ambient air is calculated by deducting the amount of emissions existing the kitchen from the total emissions produced by the cook stove. Researchers collected samples from five houses in Gauthali, a village in Chitwan, for the study. All samples were of biomass fuel burning cook stoves. 

In addition, four e-samplers were installed in four different locations for 20 days (as shown in Figure 1). Two were installed at the village centres—in Simreni and Gauthali; and two at background locations—Baghmara and Chitrasen Community Forest. The background locations don’t have any emission sources and are away from human intervention. The Chitwan National Park Air Quality Observatory (CAQO) will also be considered one of the background sites for this study.

Figure 1: Map showing the points where e-samplers were installed.

The measurements extracted from the background will later be deducted from the village measurements to calculate the contribution of village household level emissions to village ambient air quality. “The information generated from this study could help us understand the impact of household level emissions and background air pollution on villagers’ health. We will be able to calculate the percentage of risk that people are exposed to in a given area,” says Puppala. This study will extract both household and village level contributions to ambient air. Parth Sarathi Mahapatra and Alpha Thapa from ICIMOD’s Atmosphere Initiative were also involved in the study.