Acute respiratory effects of livestock related air pollution on a panel of COPD patients

Living close to livestock farms has been associated with increased symptoms in patients with chronic obstructive pulmonary disease (COPD). The causes of these effects are still poorly understood. This panel study attempts to assess the acute effects of livestock related air pollution in patients with COPD living in an area with intensive livestock farming in the Netherlands. Between February 2015 and July 2016, 82 patients took spirometry measurements twice daily during a 3-month period, resulting in 12,672 FEV1 and PEF records. Patients also kept a diary on respiratory symptoms as well as livestock related odor annoyance. Daily average ammonia (NH3) (a proxy for livestock-related air pollution) and fine particulate matter (PM10) levels were collected from monitoring stations in the area. Lung function was analyzed as decrements of >10% and >20% from their median as well as absolute values. Self-reported odor annoyance was analyzed as a dichotomous variable. All analyses were done using generalized estimated equations. We adjusted for age, gender, height, humidity, temperature, linear trend, and took multiple testing into account. We found an odds ratio of 1.14 95%CI [1.05;1.25] for decrements >20% in morning FEV1 per interquartile range (12µg/m3) increase in NH3 concentration (lag 2). Odor annoyance was negatively associated with evening PEF (-4.46 l/min 95%CI [-7.59; -1.33]). Sensitivity analyses comparing these associations between participants with different COPD definitions yielded no significant differences. No associations with symptoms were found. Our results show acute effects of livestock related air pollution on lung function in COPD patients living in close proximity to farms.