Asian Journal of Geographical Research

Open waste burning in informal settlements contributes to localized air pollution, posing significant health risks. This study investigated the distance-decay relationship of air pollutant concentrations near open waste burning sites in Kibera, Nairobi City County, Kenya. Air samples were collected at 21 sampling points across three distance ranges (0-500 m, 500-1000 m, and > 1000 m) from active burning sites over a two-month period in 2025. Pollutants measured included PM_2.5, SO₂, CO₂, and CH₄, using calibrated portable and fixed air quality monitors. Data were analyzed using linear regression and one-way ANOVA to examine relationships between pollutant concentrations and distance. PM_2.5 levels were highest within 0-500 m, reaching 150 \(\mu\)g/m³ ten times the WHO 24-hour guideline of 15 \(\mu\)g/m³ and decreased to 45 \(\mu\)g/m³ beyond 1000m. SO₂ exhibited a similar decline from 55ppb to 15ppb. Regression analysis indicated a significant negative relationship between distance and pollutant concentration (R² = 0.530), while ANOVA confirmed differences across zones (F = 49.521, p<0.001). CO₂ and CH₄ showed more gradual declines but remained elevated near burning sites, highlighting greenhouse gas contributions. Pollutant concentrations declined sharply with distance from waste burning sites, with PM _2.5 and SO₂  posing the highest immediate health risks. These findings support the establishment of buffer zones and targeted mitigation strategies in Nairobi’s informal settlements to protect public health.