Estimating long-term husbandry hydrogen sulfide exposure from satellite ammonia observations: A new epidemiological tool

Husbandry trace gases that have climate change implications such as carbon dioxide (CO₂), methane (CH₄) and ammonia (NH₃) can be quantified through remote sensing; however, many husbandry gases with health implications, e.g., hydrogen sulfide (H₂S), cannot. This study demonstrates an approach that derives H₂S concentration maps from satellite-derived ammonia concentration maps for use as an epidemiological tool by coupling in situ mobile data with remote sensing maps.

AMOG (AutoMObile trace Gas) Surveyor, a mobile air quality and meteorology laboratory, measured in situ concentration of CH₄, CO₂, NH₃, H₂S and winds at a university research dairy in coastal Southern California. In addition, NH₃ emissions from the Chino Dairy Complex in the Los Angeles Basin were derived from Infrared Atmospheric Sounding Interferometer (IASI) satellite data, 2008-2017 and the average morning winds implying a 2.7 hour flushing time, yielding 8.9 Gg NH₃ yr^-1 emissions.

The ratio of emission factors, E_F, E_F(H₂S) to E_F(NH₃) for the research dairy were applied to IASI NH₃ data to derive Chino H₂S exposure maps, which ranged to 10-30 ppb H₂S for many highly populated downwind areas. Such satellite-derived exposure maps can guide epidemiological studies, helping to identify reference and affected populations. Satellite data are direct observations and thus provide advantages relative to solely numerical transport models in complicated wind environments, although models can extend satellite observations over the diurnal cycle.