Document Type


Date of Degree

Summer 2015

Degree Name

MS (Master of Science)

Degree In

Occupational and Environmental Health

First Advisor

Anthony, T Renée

First Committee Member

Nonnenmann, Matthew W

Second Committee Member

Rohlman, Diane S


Clear evidence shows a relationship between working in swine facilities and developing respiratory illnesses. Health effects have been associated with exposures to the combination of dust, ammonia, and carbon dioxide (CO2). This study examined whether room concentrations of combustion gases could be improved by changing the in-room vented heaters common to animal production operations to heaters that vent combustion gases outside.

Concentrations of CO2 and carbon monoxide (CO) were monitored during two winter seasons, with the 2013-14 season using the traditional gas-fired heater (Guardian 60, L.B.White Co.) and the 2014-15 winter using new vented heaters (Effinity93, Modine Manufacturing Co.) Direct-reading CO (VRAE, Rae Systems) and CO2 (ToxieRAE Pro, Rae Systems) monitors were deployed at fixed stations throughout the farrowing barn to measure gas concentrations. Differences in mean gas concentrations between heater types, as well as the relationship between CO2 and temperature, sow, and piglet count, were evaluated using linear regression.

Carbon dioxide concentrations exceeded industry recommended limits (1540 ppm) on all sample days (N=18) with the standard in-room vented heaters in operation: concentrations averaged half of the TLV (2500 ppm). With the new vented heaters, 24-hour averaged CO2 concentrations exceeded industry recommended limits on only three out of 20 sample days: concentrations averaged 1400 ppm. The new heater significantly reduced CO2 by 44% and CO by 60% from 2.0 to 0.8 ppm (p2=0.75) between CO2 and production factors (temperature, sow and piglet count) for the new heater: CO2 (ppm) = 482 - 22.4(Temp °C) + 43(# sow) + 5.6(# piglet). Similar analysis for the old heater identified similar trends but substantially different intercept (1700 ppm) and temperature factor (-36.9).

While CO2 is still generated from swine respiration, we found significant reductions in room concentrations with the simple replacement of commonly used equipment. Future work will include an assessment of the longevity of these heaters in the swine barn environment

Public Abstract

Heaters that are traditionally used in swine barns release harmful gases directly into the swine barn. The purpose of this study was to see if replacing traditional swine barn heaters with heaters that sends harmful gases outside will improve swine barn conditions and ultimately protect worker health.

Gas levels were measured during two winter seasons. During the first winter the traditional heater was in operation. During the second winter the traditional heater was replaced with a heater that sends harmful gases outside. Gas measuring instruments were positioned at several locations throughout the barn. The levels of gas produced each season were compared, and other potential contributors to the gas levels found in the swine barn were also considered.

Researchers have developed recommended limits for the levels of harmful gases a person can be exposed to before they begin experiencing negative health effects. The data collected during the first winter season showed that levels produced by the first heater exceeded what has been recommended by researchers. After the new heater was installed, levels of harmful gases were dramatically reduced. The study also showed that the amount of pigs present in the room affected the levels of harmful gases present in the room.

Although the amount of pigs present in the swine barn affect the amount of harmful gases produced, gas levels may be dramatically lowered by using a heater that releases harmful gases outside. Future research will involve determining how long these heaters are able to last in swine barns.


publicabstract, carbon dioxide, combustion gas, heater, respiratory health, swine confinement, ventilation


x, 105 pages


Includes bibliographical references (pages 101-105).


Copyright 2015 Anthony Yuan-Jung Yang