A white piglet chewing hay

A white piglet chewing hay

  • Air quality is the degree of pollution of air.
  • The air quality can be determined by measuring the concentration of pollutants in the air.
  • Air quality has a direct influence on health, welfare and production performance of livestock.

  • The high concentrations of noxious gases, dust, and airborne microorganisms can reduce the production efficiency and the general welfare of farm animals.
  • Long term exposure to particulates in livestock buildings might also affect the respiratory health of farm workers.
  • Dust in animal buildings contains many biologically active substances such as bacteria, fungi, and endotoxins that are suspected to be hazardous to human health.

  • Airborne emissions include ammonia, methane, nitrous oxide, particulates like dust and microorganisms.
  • In addition, other potentially harmful substances such as heavy metals, antibiotic residues and components of disinfectants might be also emitted from livestock building that are potentially damaging to ecosystems.

Importance of air quality

  • Animals that continually exposed to bad air quality had reduced productivity and increased the stress.
  • Maintaining good air quality is not only important for the productivity of the animals, but also for the welfare of the animals.

Benefits of improving the air quality

  1. Improves the health, welfare and production performance of the animals.
  2. Improves the health and safety of producers and workers.
  3. Reduces emissions of harmful pollutants to the outside environment which helps reduce nuisance complaints.
  4. Results in significant energy and economic savings.
  5. Prolongs the life of building structures.

  • Generally air quality is affected by weather, livestock facilities and management conditions.
  • Air quality is getting worse during light wind conditions, as pollutants cannot be blown away.

Pollutants

Ammonia

  • Ammonia (NH3) is an important pollutant gas.
  • Livestock wastes account for 39% of global emissions.
  • Among them, pig production is globally responsible for about 15% of NH3 emissions associated to livestock.

Repartition of sources of global ammonia emissions (Galloway et al., 2004).

Repartition of sources of global ammonia emissions (Galloway et al., 2004).

  • Ammonia is emitted from manure in livestock buildings, manure storage facilities and during manure application to soils.
  • Ammonia in livestock facilities results primarily from the breakdown of urea (present in urine) by the enzyme urease (excreted in feces).
  • Typical ammonia levels in well-ventilated buildings are 10 to 20 ppm.
  • Ammonia can be easily removed from livestock buildings by proper ventilation because it is lighter than air.

Summary of effects in humans following acute ammonia exposure.
Concentration (mg/m3) Exposure time Effects reported
3480 30 min Death
350 30 min Nasal and throat irritation
70 6 h Transient irritation of eyes, nose, and throat
56 2 h Coughing, eyes, nose, and throat irritation
35 2 h No adverse effect
0.5-37(mean = 3.5) Odour threshold
12-14 Odour complaint level

Nitrogen transformations and ammonia production in manure

Nitrogen (N) transformation in livestock manure and releases to the atmosphere (NH3, ammonia; NH4+, ammonium; NO3−, nitrate; N2O, nitrous oxide; N2, dinitrogen; g, gaseous form; l, liquid form) (adapted from Philippe et al., 2011).

Nitrogen (N) transformation in livestock manure and releases to the atmosphere (NH3, ammonia; NH4+, ammonium; NO3−, nitrate; N2O, nitrous oxide; N2, dinitrogen; g, gaseous form; l, liquid form) (adapted from Philippe et al., 2011).

Suppression methods

  1. Decreasing of the length of the time manure remained.
  2. Keeping buildings and the animals clean and dry.
  3. Separation manure from urine.
  4. Using acidifying agents to suppress ammonia emissions from manure.
  5. Filtration.
  6. Landscaping: Trees, shrubs and other vegetative barriers planted around livestock buildings have the potential of reducing ammonia emissions.

Dietary strategies

  1. Reduced crude protein (CP) diets containing synthetic amino acids have been shown to reduce N excretion, which leads to reduce NH3 emissions.
  2. Reducing NH3 emissions from the slurry can also be achieved by the addition of fibrous feedstuffs in the diet.
  3. Feed additives: Non-starch polysaccharides enzymes, yucca extract, zeolites, probiotics, and so on.

Hydrogen sulphide

  • Hydrogen sulfide (H2S) is a toxic gas and has potential to cause health problems if the concentration becomes too high.

  • Hydrogen sulphide is heavier than air, soluble in water, and can accumulate in the livestock buildings.
  • It has a rotten-egg odour and it can be easily detected at low concentrations.

Suppression methods

  • Modifying diets to balance rations reduce hydrogen sulphide emissions.
  • Frequent removal of manure from static pits significantly reduces hydrogen sulphide.
  • Physical, chemical and biological treatment of stored manure such as manure additives and oil sprinkling.
  • Biofiltration is an effective method for reducing the emissions of hydrogen sulphide.

Particulate matters (Dust)

  • Particulate Matter (PM) is an unusual air pollutant in that it is defined by its physical morphology rather than chemical identity.

  • PM10: inhalable particles, with diameters that are generally 10 micrometers and smaller

  • PM2.5: fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.

Population exposure to fine particulates (PM2.5).

Population exposure to fine particulates (PM2.5).

  • Dust from swine/pourtly barns originates from feed, bedding material, manure and the animals themselves.
  • Many of the respirable dust particles are odorous because of their fecal origin.

The factors determining the amount of dust in confinement includes

  1. Animal activity
  2. Temperature
  3. Relative humidity
  4. Ventilation rate
  5. Stocking density
  6. feeding methods

  • Dust is related to the odor
  • Removal of dust in animal production facilities can reduce the odour in the air by 65-75%.
  • Filtering the dust from the exhaust air reduced VOC–odor emissions from swine buildings by up to 65%.

Suppression methods

  1. Ventilation: The major method of controlling dust and air contamination in enclosed livestock facilities is by mechanical ventilation.
  2. Air Misting: The oil/water spraying is a promising technique for dust control in livestock buildings.
  3. Fibrous Filter
  4. Wet Collectors: Wet scrubber using water to capture dust particle are very efficient in removing dust particles from air, however its use is not recommended in livestock building due to the needs for handling large amount of air in livestock buildings.