Introduction

Longitudinal studies investigating air pollution from livestock farms and respiratory health effects in neighboring residents are lacking. The aim of this study was to assess the relationship between livestock farm exposures and lung function decline over a 7-year period in people living in livestock-dense areas.

Methods

Spirometry was performed in 2014/2015 and 2021/2022 for 847 adults (28-80 years). We analyzed the annual rate of change in FEV1, FVC, FEV1/FVC, PEF and MMEF in relation to the annual-average livestock-emitted endotoxin concentration at the home address, which was predicted by dispersion modeling at baseline. Data analysis was performed using generalized additive models with a non-linear term for endotoxin exposure. Models were adjusted for age, sex, height, BMI, education level, smoking history, atopy, and growing up on a livestock farm.

Results

Endotoxin exposure was not associated with the annual rate of change in lung function (p>0.05). Subjects with a farm childhood had larger annual decreases in FEV1 (-5.63 ml/y, p=0.018) and MMEF (-11.15 ml/s per year, p=0.032), compared to those who did not grow up on a farm. Models stratified for atopy revealed that the association between accelerated FEV1 decline and farm childhood was more pronounced in individuals without atopy.

Conclusions

Early-life farm exposures were associated with accelerated lung function decline in non-atopic adults. As growing up on a farm was associated with increased livestock exposure later in life (e.g. visiting farms), further investigation of current exposures is needed. Air pollutants other than livestock-emitted endotoxin could also play a role.