Airborne fine particulate matter (PM2.5) represents the greatest ambient air pollution risk to health. Wildfires and managed burns, together referred to hereafter as ‘landscape’ fires, are a significant PM2.5 source in many regions worldwide, able to affect air quality in areas far away from the fires themselves. We use 0.125°, 3 hourly outputs (2016-2019) from the Copernicus Atmospheric Monitoring System (CAMS) to investigate patterns of global population exposure to ambient surface level PM2.5, and specifically to the contribution coming from landscape fires. We calculate both the air quality impacts and annual average mortality at the level of the nation state, and our analysis highlights both the burden of poor air quality and the significance of landscape fire sources in developing nations in particular. We find 143 countries to have an average population weighted (PW) total PM2.5 surface level concentration exceeding the 10 μg.m-3 guideline recommended by WHO, with 67.2 million people annually exposed to PM2.5 levels classed as ‘hazardous’ (> 250.5 μg.m-3) according to the US Environmental Protection Agency (EPA) air quality index (AQI). Landscape fires alone result in 44 million people annually being exposed to air quality considered unhealthy (PM2.5 > 55 μg.m-3), and 4 million to that considered ‘hazardous’ to health (> 250.5 μg.m-3). Populations in central and west Africa and south and south east Asia are most affected by the landscape fire smoke, and eight countries exceed the WHO annual mean 10 μg.m-3 guideline from this source only - with the contribution from fires highest in Laos (61% of the total PM2.5), Democratic Republic of Congo (45%) and Sierra Leone (44%). Combining published dose-response functions with these landscape-fire PM2.5 contributions, we estimate that 677,745 premature deaths annually result from exposure to landscape fire smoke, with almost 39% of these in children under five. This mortality represents between 8 and 21% of the estimated 3.2 to 8.9 million people dying annually from outdoor air pollution exposure, highlighting landscape fires as a significant contributor. Our results indicate that environmental programmes aimed at lessening the use of fire in land clearance and agricultural residue management in developing nations would very likely result in significant co-benefits for health.