A critical review of advancement in scientific research on food animal welfare-related air pollution

Air pollution generates hazardous pollutants that have resulted in safety, health, and other welfare issues of food animals. This paper reviewed scientific research advancement in food animal welfare-related air pollution based on 219 first-hand research publications in refereed journals (referred to as RPs) over the past nine decades. Scientific studies in this area began in the 1930s. The number of RPs has increased significantly with each decade from the 1960s to the 1980s, then decreased until the 2010s. Twenty-six countries have contributed to this multidisciplinary research. About 52% of the studies were conducted in the U.S. and U.K. Research activities have surged in China since the 2010s. On-farm discoveries in air toxicity that resulted in animal death or injury were all from observational studies. About 75% of the studies were experimental and conducted primarily under laboratory conditions. Ammonia (NH3) was the main pollutant in 59% of the RPs, followed by dust, hydrogen sulfide (H2S), bacteria and endotoxins, carbon dioxide (CO2), carbon monoxide (CO), silo gas, sulfur dioxide (SO2), and odor. Approximately 23% of RPs reported multiple pollutants in the same study. The most intensively studied animal species were poultry (broilers, hens, turkeys, ducks, and eggs and embryos in 44% of the RPs) and pigs (also 44%), followed by cattle, and sheep and goats. Scientific investigations in this area were driven by the research focuses in the areas of animal agriculture and industrial air pollution. Some major research teams played important roles in advancing scientific research. However, research in this area is still relatively limited. There is a great need to overcome some technical challenges and reverse the trend of decreasing research activities in North America and Europe.

Automated summary

This paper reviewed scientific research advancements in food animal welfare-related air pollution over the past nine decades. The studies have shown that air pollution is closely related to the health and safety of food animals, with research primarily conducted in the United States, United Kingdom, and China. Experimental studies were mainly conducted in laboratory conditions, focusing on pollutants such as ammonia and dust. Observational studies identified air toxicity causing animal death or injury, and there is a need to address the decreasing research activities in North America and Europe.