INTRODUCTION According to ILO (2000), in developing countries about 59 per cent of labour force belongs to the agriculture sector. This is a particularly serious concern from the viewpoint of promoting the health of a population and reduction of social vulnerability in a country like Mozambique where more than half of the population depends on agriculture as their means of survival and wage earning. The current study attempts to address the agriculture mineral dust as occupational hygiene and health risk factors among agriculture workers, taking into account that dust that is breathed in may contain quartz, known as a carcinogenic and pathogenic agent. OBJECTIVE OF THE STUDY The study aims to pinpoint risk potential to health that may be caused by mineral dust through assessing occupational exposure doses to respirable dust and quartz during plowing, and primary and secondary tilling operations identified in the study, as the major dust risk operations; and the more prevailing operations in maize and root plant on medium sized farms‟ production cycle. MATERIALS AND METHODS Sampling of dust was conducted on 2 medium sized farms selected by convenience in the district of Boane (study setting) based on geological map soil characterisation of the study area. Full-time period dust samples were collected from 4 different tractor operators. The tractor operators were identified as the risky group. In total were taken seventy valid samples; thirty-nine from maize and thirty-one from root plant. Three tractor operators were fully engaged in maize cultivation and 1 was engaged in root plant during the period of the study data collection. In all occasions, the „open-cabbed‟ tractor machines were observed and used by tractor operators. The involved sampling subjects‟ operators were informed in advance about the study purpose and they accepted participation in the research. Nineteen dust samples were randomly selected for determination of the quartz fraction using the MDHS 101 Infrared Spectrophotometer Method. Active dust sampling MDHS 14/3 HD-cyclone method was applied with GLA 5000 filter type. All quality control procedures applied in active dust sampling method and gravimetric determination of concentration were checked in order to accept or reject samples for further analysis and determination of exposure concentration. RESULTS Standard statistical procedures and sampling strategy data analysis and interpretation procedures, including the SPSS software version 11.5 were used to produce valid results and findings. In the specific case of the agriculture sector, workers are found in changeable conditions and working time, therefore the effective working time distribution was estimated varying at a level of 311.6 min., 95 per cent CI (294-329.7). The observed minimal and maximal values were 179 and 500 min., respectively. The filter medium potential contamination was checked out through determination of the mass variation of the blank samples. The filter contamination was assumed possible through absorption and/or adsorption of humidity at level of minus 0.00407 mg with lower limit of minus 0.01 and upper limit of 0.00183 mg. The results on exposure indicate high exposure dose in maize crop cultivation in contrast to root plant crop cultivation. The findings show that in medium-sized farming, the average exposure to respirable dust is 0.702 (SD 0.571) and the average exposure for respirable quartz is 0.074 (SD 0.06). About 96 per cent of respirable dust exposure measurements were found in compliance with the South Africa standard for respirable dust; and for respirable quartz 74 per cent, 45 per cent and 17 per cent of exposure measurements were in compliance with the SA, NIOSH and ACGIH occupational exposure limits respectively. Each tractor operator‟s measurements showed a significant variation of the exposure concentration, probably due to the intraday and interday variation. The exposure measurements geometric standard deviation (GSD) was found equal or above 2.0 for both maize and root plant measurements and this indicates the influence of environmental factors in the exposure profile variation. CONCLUSION The research is supportive of some international published studies in which respirable quartz exposure in agriculture sector, although highly variable, has potential significance for over-exposure. The measurements of exposure to respirable quartz have shown over-exposure scenarios. However some were found below the permitted exposure limits.