Abstract

Suspended particulate and bioaerosol levels were measured at three sites downwind of an agricultural non-point source during the wheat harvesting season. Suspended particulates were detected at mean values ranging from 10000 to 2420 µg m⁻³ at distances of from 20 to 60 m downwind of the source, respectively. Airborne viable bacterial counts were recorded at mean values ranging between 10⁴ and 10⁶ colony forming units (cfu) m⁻³, whereas, Gram negative (Gram −ve) bacteria varied between 10³ and 10⁵ cfu m⁻³. Fungi levels were detected at mean values varying between 10⁵ and 10⁶ cfu m⁻³. However, streptomycetes were found at lower counts than those recorded for viable bacteria and fungi. Total viable bacteria, Gram −ve bacteria, fungi and streptomycetes associated hay fragments were determined at mean values of 1.5 × 10⁶, 1.6 × 10³, 2.2 × 10⁴ and 6 × 10³ cfu g⁻¹ of hay, respectively. Cladosporium, white and red yeasts as well as Alternaria were the predominant airborne fungi, whereas, Alternaria was the dominant species associated with hay fragments. Pseudomonas, Acinetobacter and Enterobacteriaceae were the dominant Gram −ve bacteria. The most common fungal genera, such as Cladosporium and Fusarium (minor short axis), as well as Streptomyces species have an aerodynamic diameter (dae) of less than 5 µm, which can penetrate and deposit in the alveoli. Farmers and nearby residents are exposed to high levels of organic dust and bioaerosols during the wheat harvesting season. This may cause health problems in exposed persons based on toxic or allergic reactions.