Objectives The rate of lung function decline has been recognised as a predictor for mortality. Workers in grinding wheel manufacturing exposed to inorganic fine particulates (e.g. free silica, silicon carbide, or aluminium oxide). Information about their longitudinal lung function change is relatively limited.

Method Forty five workers involved in grinding task of grinding wheel manufacturing were enrolled. Their lung function test results in the past three years (2010 ∼ 2012) were collected. Particulate matters with aerodynamic diameter less than 2.5 (PM2.5) and 10 (PM10) μm in their workplace were measured using real-time monitor. Controls (n = 175) were health care workers, who had regular lung function examination for more than three times. Linear regression was used to calculate the rate of individual lung function decline and the standard error. Multiple linear regression for individual decline rate was adjusted for age, gender, and smoking status, and was weighted by the inverse of square standard error.

Results The average concentration of PM2.5 and PM10 in the grinding room were 60 and 186 μg/m3, respectively. Mean decline rates of forced expiratory volume in 1 second among non-smokers and smokers were 33.2 and 108.1 ml/year in grinding workers, and 13.1 and 52.7 ml/year, respectively, in controls. After adjustment, age (β = −0.95, p = 0.0001), grinding work (β = −42.6, p = 0.002), and current smoking (β = −33.0, p = 0.014) were associated with lung function decline rate. The interaction term between grinding and smoking is not statistically significant.

Discussion The rate of longitudinal lung function decline is increased in grinding workers of grinding wheel manufacturing. Improvement in dust control and personal protective equipment usage are needed, as well as the further lung function monitoring annually.