Abstract
Airborne emissions from concentrated animal feeding operations (CAFOs) have the potential to pose a risk to human health and the environment. Here, we present an assessment of the emission, dispersion, and health-related impact of ammonia and hydrogen sulfide emitted from a 300-head, full-scale dairy farm with an exercise yard in Beijing, China. By monitoring the referred gas emissions with a dynamic flux chamber for seven consecutive days, we examined their emission rates. An annual hourly emission time series was constructed on the basis of the measured emission rates and a release modification model. The health risk of ammonia and hydrogen sulfide emissions around the dairy farm was then determined using atmospheric dispersion modeling and exposure risk assessment. The body mass-related mean emission factors of ammonia and hydrogen sulfide were 2.13 kg a−1 AU−1 and 24.9 g a−1 AU−1, respectively (one animal unit (AU) is equivalent to 500 kg body mass). A log-normal distribution fitted well to ammonia emission rates. Contour lines of predicted hourly mean concentrations of ammonia and hydrogen sulfide were mainly driven by the meteorological conditions. The concentrations of ammonia and hydrogen sulfide at the fence line were below 10 μg m−3 and 0.04 μg m−3, respectively, and were 2–3 orders of magnitude lower than the current Chinese air quality standards for such pollutants. Moreover, the cumulative non-carcinogenic risks (HI) of ammonia and hydrogen sulfide were 4 orders of magnitudes lower than the acceptable risk levels (HI = 1). Considering a health risk criterion of 1E-4, the maximum distance from the farm fence line to meet this criterion was nearly 1000 m towards north-northeast. The encompassed area of the contour lines of the ambient concentration of ammonia is much larger than that of hydrogen sulfide. However, the contour lines of the ammonia health risk are analogous to those of hydrogen sulfide. In general, the ammonia and hydrogen sulfide emissions from the dairy farm are unlikely to cause any health risks for the population living in the neighborhood.
Highlights
Concentrated animal feeding operations (CAFOs), such as dairy and cattle farms, have been extensively developed in recent decades to meet peoples’ demands for meat and dairy products (Hu et al 2017)
The emission factor of ammonia and hydrogen sulfide was realized by a twofold strategy: (1) the emission factor e was first determined directly from the measurements; (2) using the release modification factor R, the measurements were detrended to eliminate the impact of the predictors during the measurements, which gives the reference emission factor e0
The emission rate E can be calculated by the body mass-specific emission rate eM and the activity value M according to E = eM M
Summary
Concentrated animal feeding operations (CAFOs), such as dairy and cattle farms, have been extensively developed in recent decades to meet peoples’ demands for meat and dairy products (Hu et al 2017). Gaseous compounds emitted from dairy farms have evoked increasing social and environmental concerns (Jahne et al 2015; Wang et al 2018). Residents are concerned with potential health risks due to gas emissions from dairy farms. Workers and neighbors of CAFOs such as dairy farms can be directly exposed to emitted noxious gases primarily through inhalation. Long-term exposure to these pollutants has been associated with potential health risks such as respiratory irritation and central nervous system damage (Jaars et al 2018; Wu et al 2018). There is a need to evaluate the potential health risks induced by noxious gases emitted from CAFOs such as dairy farms
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