Asthma and nasal allergies occur less frequently in people who live near livestock farms. It was already known that these occur less frequently in people who grew up on farms; the study shows that this also applies for people who live in the surrounding area. Fewer people with COPD, a chronic respiratory tract disease, live near livestock farms. But the COPD patients who do live there are more likely to have severe symptoms, in comparison with people who live farther away from livestock farms. COPD patients who live near livestock farms also use more medication against respiratory symptoms and their pulmonary function is reduced. People with COPD are therefore an important risk group for respiratory symptoms with respect to livestock farms.
The researchers have observed reduced pulmonary function in people who have a large number of livestock farms in their immediate surroundings. This is particularly noticeable among people who live less than 1 km away from fifteen or more of such farms. It seems most likely that this is caused by exposure to substances produced by livestock farming. The researchers observed not only that people living close to a large number of livestock farms have reduced pulmonary function, but also that pulmonary function throughout the research area is reduced if there is a high concentration of ammonia in the air. Ammonia is a substance that is released by livestock farms (particularly in manure). The effects of exposure to ammonia are comparable to those of exposure to traffic in the city.
The researchers found more cases of pneumonia in the research area than in the rest of the country, a difference that has however become smaller since the Q fever epidemic of 2007-2010. When the researchers analysed this according to the type of livestock farm, a relationship was found between poultry farms within a distance of 1 km from the place of residence and a slightly elevated risk of pneumonia. There are strong indications that emissions of fine particulates from livestock farms make people more susceptible to infections. The possibility that specific pathogens from poultry cause a portion of the cases of pneumonia cannot be excluded. It is not possible to exclude the fact that other types of livestock farming may also contribute to the elevated risk of pneumonia in various rural areas.
The study Livestock Farming and the Health of Local Residents was carried out by the Dutch National Institute for Public Health and the Environment (RIVM), Utrecht University (IRAS), Wageningen UR and the Netherlands Institute for Health Services Research (NIVEL) using various methods to examine the possible health effects. Data from GPs was used, questionnaires were completed and almost 2500 people had a medical examination. The air quality and emissions from a number of types of livestock farms were determined at various locations. The study took three years and was financed by the Ministry of Health, Welfare and Sport, the Ministry of Economic Affairs and partly by the Longfonds (Lung Fund) charity. The results of ongoing follow-up studies will be published at the end of 2016.