Setting odour impact index and developing a setback distance model for livestock farms

密集畜牧业活动产生的气味和有毒气体（H2S和NH3）排放已成为公众关注的问题，因为它们对环境的影响和对邻近居民的潜在健康影响。确定基于科学的后退距离已成为迫切需要。利用气味扩散模型预测下风向的气味羽流，然后根据可接受的气味标准确定合理的折流是一种科学的方法。源气味释放速率是气味扩散模型所需的基本数据，它随动物和气候条件的变化而不断变化。在气味扩散模型中，需要揭示和考虑昼夜和季节性气味排放曲线。确定主要气味源将有助于开发和应用针对主要来源的气味控制技术。考虑气味强度、攻击性、持久性、频率等的可接受气味标准（如气味影响指数），需要建立。H2S和NH3是有毒气体，也是牲畜气味的主要气味物质，需要量化。

Odour and toxic gas (H2S and NH3) emissions from the intensive livestock operations have become a public concern due to their environmental impact and potential health impact on neighbouring residents. Determining science-based setback distance has become an urgent need. Using odour dispersion model to predict odour plume downwind and then determine reasonable setbacks based on acceptable odour criteria is a scientific approach. Source odour emission rates, which are changing constantly with animal and climatic conations, are the basic data needed for odour dispersion modeling. The diurnal and seasonal odour emission profiles need to be revealed and considered in odour dispersion modeling. Identifying major odour sources will help development and applying odour control technologies targeting major sources. Acceptable odour criteria (such as odour impact index) considering odour intensity, offensiveness, persistence, frequency, etc., need to be established. H2S and NH3 are toxic gases and the major odorants of livestock odour and need to be quantified.