Air Pollution from Industrial Swine Operations and Blood Pressure of Neighboring Residents

Steve Wing,¹ Rachel Avery Horton,¹ and Kathryn M. Rose^1,2

¹Department of Epidemiology, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA; ²Health Sciences Research, SRA International Inc., Durham, North Carolina, USA 


Abstract

Background: Industrial swine operations emit odorant chemicals including ammonia, hydrogen sulfide (H₂S), and volatile organic compounds. Malodor and pollutant concentrations have been associated with self-reported stress and altered mood in prior studies.


Objectives: We conducted a repeated-measures study of air pollution, stress, and blood pressure in neighbors of swine operations. 


Methods: For approximately 2 weeks, 101 nonsmoking adult volunteers living near industrial swine operations in 16 neighborhoods in eastern North Carolina sat outdoors for 10 min twice daily at preselected times. Afterward, they reported levels of hog odor on a 9‑point scale and measured their blood pressure twice using an automated oscillometric device. During the same 2‑ to 3‑week period, we measured ambient levels of H₂S and PM₁₀ at a central location in each neighborhood. Associations between systolic and diastolic blood pressure (SBP and DBP, respectively) and pollutant measures were estimated using fixed-effects (conditional) linear regression with adjustment for time of day.


Results: PM₁₀ showed little association with blood pressure. DBP [β (SE)] increased 0.23 (0.08) mmHg per unit of reported hog odor during the 10 min outdoors and 0.12 (0.08) mmHg per 1‑ppb increase of H₂S concentration in the same hour. SBP increased 0.10 (0.12) mmHg per odor unit and 0.29 (0.12) mmHg per 1‑ppb increase of H₂S in the same hour. Reported stress was strongly associated with BP; adjustment for stress reduced the odor–DBP association, but the H₂S–SBP association changed little.


Conclusions: Like noise and other repetitive environmental stressors, malodors may be associated with acute blood pressure increases that could contribute to development of chronic hypertension. 


Key words: agriculture, air pollution, community-based participatory research, environmental justice, epidemiology, health disparities, odors, psychosocial stress. 


Environ Health Perspect 121:92–96 (2013). http://dx.doi.org/10.1289/ehp.1205109 [Online 28 October 2012]


Address correspondence to S. Wing, Department of Epidemiology, CB# 7400, 2101F, McGavran-Greenberg Hall, University of North Carolina, Chapel Hill, NC 27599-7400 USA. Telephone: (919) 966-7416. Fax: (919) 966-2089. E-mail: steve_wing@unc.edu


J. Creason, D. Taylor Davis, B. Denzler, J. Godwin, B. Graham, G.R. Grant, S. Hutton, A. Lowman, N. Muhammad, J.W. Scott, J. Thompson, J. Watkins, and S. Wolf played key roles in field work and study support. S. Wolf, J. Creason, K. Foarde, J. Raymer, and S. Schiffman helped to design the study. C. Gray provided research assistance. The Concerned Citizens of Tillery, the Alliance for a Responsible Swine Industry, and other community-based organizations, which must remain unnamed to protect confidentiality, contributed to the design and conduct of the research. We are indebted to the study participants for their hard work and commitment to collection of data.


This research was supported by the National Institute of Environmental Health Sciences (NIEHS; grant R01 ES011359), Biostatistics for Research in Environmental Health Training Grant from the NIEHS (grant 5-T32-ES07018), and U.S. Environmental Protection Agency cooperative agreement CR829522. 


S.W. provided pro bono testimony in legal proceedings related to landfills and provided pro bono advice on radiation and health for law firms, one of which made a gift to the University of North Carolina. He conducted research, funded by the Water and Environment Research Foundation, on symptoms reported by neighbors of areas where sewage sludge is applied to land. The other authors declare they have no actual or potential competing financial interests. 


Received 16 February 2012; Accepted 18 October 2012; Online 28 October 2012.