Effects of Air Pollution on the Honey Quality in Thimphu District, Bhutan

Abstract

Integrating beekeeping into farming operations is crucial for improving livelihoods, but little is known about the effects of air pollution on bees and honey quality in Bhutan. This study investigates the concentrations of heavy metals found in the honey of summer season from both rural and urban areas of the Thimphu District, Bhutan. AirVisual Pro was used to record PM_2.5, PM₁, temperature, and humidity simultaneously in urban and rural areas of the Thimphu District in 2022. Honey samples and airborne dust particle (ADP) samples were collected from both the study sites to determine the concentrations of heavy metals (Pb, Ni, Cu, and Cd) using atomic absorption spectrophotometer (AAS). The results showed that PM_2.5 and PM₁ concentrations were higher in both study sites during the pre-monsoon, post-monsoon, and winter seasons. The concentrations of Cu and Ni in urban ADP were 2.43 and 2.29 times higher, respectively, compared to rural ADP. Three ADP samples from the rural and five samples from the urban had a Cd content more than 3 µg/g. Ni and Pb were absent in the honey samples from both locations, and Cu were within the Codex Alimentarius Commission (CAC) permissible limits. Three honey samples from both the study sites had Cd levels higher than 0.30 µg/g. Given the toxicity of Cd in honey, further empirical researches are required for identifying and characterizing Cd sources in honey samples of Thimphu District.