Construction workers are routinely exposed to airborne particulate matter (PM) generated by activities such as cutting, drilling, demolition, and excavation. In Sri Lanka, where dust management practices on construction sites are often inadequate, this exposure poses a serious but underexamined occupational health risk. This study assessed PM exposure levels and associated health effects among construction workers through two complementary methods: microscopic analysis of dust samples collected from nine active construction zones in Colombo, and a structured questionnaire survey administered to 166 workers. Dust samples were sieved at 50 μm and analysed using a ZEISS Stemi 305 stereo microscope. Survey data were analysed using SPSS v27 with descriptive statistics, chi- square tests, and Spearman rank correlation. Microscopic analysis confirmed the presence of fine and ultrafine particles (PM1, PM2.5, PM10) across all nine activity-specific samples. Survey results showed that 30.7% of workers reported current health problems, and 50 workers had pre-existing respiratory conditions. A statistically significant association was found between dust exposure frequency and reported health problems (χ² = 21.304, p < 0.001). Workers exposed daily had the highest incidence of illness (19 out of 33). PPE satisfaction was also significantly linked to health outcomes (χ² = 20.019, p < 0.001), and formal safety training was positively correlated with correct PPE use (ρ = 0.358, p < 0.001). Despite high PPE provision, workers reported dust bypass through masks, and fewer than 25% confirmed regular health check-ups. The findings highlight critical gaps in dust control, PPE adequacy, and health monitoring in the Sri Lankan construction sector, and provide evidence-based recommendations for targeted intervention.