More than one billion people worldwide experience at least one day of air pollution caused by indoor fires each year. This is according to a study published in Science Advances.

Particles from fires that are smaller than 2.5 micrometers (PM 2.5) unquestionably cause damage to health. However, little is known about exposure to these particles in indoor environments. Researchers from the School of Public Health at the University of California, Los Angeles, used modeling to map concentrations with high spatial resolution from 2003 to 2022 globally.

According to the study’s results, approximately 1.009 billion people experienced at least one day per year of significant indoor fire-related air pollution during the period 2003-2022. However, this exposure was unevenly distributed across the globe. The highest average annual concentration of indoor fire-related PM 2.5 relative to population density was found in Africa, followed by Asia and South America.

Additionally, simulations of global air purifier device deployment and the related costs per country revealed disparities in this sector as well. The estimated worldwide cost for purchasing and using these devices (including electricity consumption and filter replacement costs) to keep indoor PM 2.5 levels below the WHO recommended limit of 5 μg/m³ may exceed four trillion US dollars annually. Of this, 69 billion dollars are allocated to reducing particulates from fires.