Direct-reading gas monitors can alert farmers to life-threatening concentrations of gases on the farm. These monitors are relatively inexpensive and easy to use. Below are guidelines to identify hazards and select sensor types based on potential hazards in your farming operation.
Gas
Hydrogen Sulfide (H2 S)
- Health effects at low levels (2 to 20 ppm): nausea, headache, dizziness
- Health effects at medium levels (100 to 300 ppm): altered breathing, fluid in lungs
- Health effects at high levels (500 to 700 ppm): collapse, death
Methane (C H4, L E L)
- Health effects at low levels (less than 0.1% or 1000 ppm): not harmful
- Health effects at medium levels (less than 1% or 10,000 ppm): no known toxicity
- Health effects at high levels (5 to 15% or 50,000 ppm): explosive
Ammonia (N H3)
- Health effects at low levels (5 to 20 ppm): odor, eye irritation
- Health effects at medium levels (20 to 50 ppm): moderate eye and upper respiratory tract irritation
- Health effects at high levels (2500 ppm): chemical pneumonitis, edema, cyanosis, death
Carbon Dioxide (C O2)
- Health effects at low levels (600 to 2000 ppm): muscle stiffness, drowsiness, poor judgment
- Health effects at medium levels (5000 ppm): 8-hour maximum
- Health effects at high levels (30,000 ppm or 3%): increased pulse rate, nausea, mental impairment
Carbon Monoxide (C O)
- Health effects at low levels (less than 9 ppm): comfortable living concentration (35 ppm = 8 hours allowable)
- Health effects at medium levels (200 ppm): headache, dizziness, nausea in 2 hours
- Health effects at high levels (400 ppm): life threatening in 3 hours
Children, elderly, pregnant women are at risk at lower C O concentrations. The concentrations listed are relevant only at sea level.
Livestock Production
[Simple drawing of a cow and a pig.]
Manure Storage
- Under slatted floor, outside lagoon, pit, or tank
- Sensor types: H2 S, L E L, N H3
Manure Pumping
- Under slatted floor, outside lagoon, pit, or tank
- Sensor types: H2 S, L E L
Foaming Manure
- If foaming is present, significant methane risk (see additional materials)
- Sensor types: H2 S, L E L
Pressure Washing
- Inside building
- Sensor types: H2 S, L E L, N H3
Animal
- Exhaled breath
- Sensor types: C O 2
Gas-Fired Heaters
- Combustion byproducts
- Sensor Types: C O 2, C O
Grain Bins
[Simple drawing of two grain bins.]
Inside Bins
- Out-of-condition grain, gas-fired dryers
- Sensory types: C O, C O2
Equipment
- Overheated equipment, smoldering product
- Sensor types: C O
[Logo: Great Plains Center for Agricultural Health]