Effect of heater type on CO/CO2 concentrations in a farrowing barn

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