Environmental Hygiene

Environmental Hygiene - Air Hygiene

Air is a mixture of colorless and odorless gases
Composition remains constant due to continuous exchange of gases between animals and plants
At 0°C and 760 Hg, the constituents are:
- Nitrogen: 78.03%
- Oxygen: 21.00%
- Carbon dioxide: 0.03%
- Argon: 0.94%
- Inert gases (Neon, Helium, Krypton, Xenon, Ozone, Hydrogen, Nitrogen oxide, Nitrous oxide, ammonia, others): traces
Composition remains fixed due to the immensity of the atmosphere and continuous gas exchange between animals and plants.
Carbon dioxide (CO2):
- Normal atmosphere contains 0.03% (300ppm)
- Maximum permissible limit is 0.1% (1000ppm)
- Sources:
  - Expiration of humans and animals
  - Decay and decomposition of manure and organic matter
  - Burning of fuel materials
  - Underground accumulation
  - Eructation and belching of animals
  - Over amounts are removed by plant exchange
- Precipitation by rain forms carbonic acid
- Forms inorganic compounds as carbonates
Hygienic Significance of CO2:
- Not toxic but increases at the expense of oxygen
- Presence indicates air pollution
- Increased levels indicate bad ventilation, overcrowding, or faulty drainage systems
- Overdoses can lead to:
  - 50,000 ppm: deep, rapid respiration
  - 100,000 ppm: violent panting, narcosis
  - 100,000 ppm: dizziness, unconsciousness
  - 400,000 ppm: struggling, coma, death
- Higher CO2 in laying hens decreases egg production
- Chronic CO2 poisoning can occur in northern farms during winter
  - Leading to: depressed respiration, poor lung aeration, decreased appetite, and reduced productivity
Humidity:
- Definition: Amount of water vapor in the air
- Absolute Humidity: Actual amount of water vapor in the air at a given temperature
- Relative Humidity (RH%): Ratio between absolute humidity and maximum saturation at the same temperature (RH%= Absolute humidity/ Maximum saturation *100)
- Saturation Deficit: Difference between maximum saturation and absolute humidity
- Dew Point: Temperature at which water vapor condenses
- Sources of humidity in stables:
  - Evaporation of liquid manure and urine
  - Accumulation of wet bedding in poorly ventilated stables
  - Evaporation of water from cleaning and feeding materials like bran mash
Animal Specific Humidity Amounts: (Units unspecified in the text)
- Calf (birth-12 weeks): 55-135
- Growing cows: 180-370
- Adult cows: 450
- Chickens (0-7 weeks): 0.04-1.25
- Layers: 1.8-3
Hygienic Significance of RH%:
- Increased dust formation
- Increased viability of microorganisms
- Increased insect and disease vectors
- Increased susceptibility to infection in animals
- Regulation of animal body temperature through Evaporation, Respiration, and Conduction
Air Pollution:
- Any substance (natural, man-made, or animal-derived) present in the air at a concentration high enough to affect animals, people or plants.
- Natural sources: Volcanic gases, dust, pollen, grains, viruses, fungi, bacteria.
- Man-made sources: Smoking, industrial plants, motorized traffic, pesticides, radioactive materials.
- Animal sources: Ammonia, nitrites, smells, fecal matter.
Air Impurities:
- Solid impurities (biological and dust):
  - Organic dust: Includes molds, fungi, bacteria, viruses.
  - Inorganic dust: Lime salts, iron, silica, sodium chloride.
- Gaseous impurities (diffused):
  - Group 1: Carbon dioxide (CO2), Carbon monoxide (CO), Ammonia, Nitrogen dioxide, and other noxious compounds
  - Group 2: Sewer gases (Hydrogen sulfide, indol, methane)
Ammonia (NH3):
- Sources: Decomposition of urine and manure, heating of organic matter (like coal and oil) in the absence of oxygen
- Normal level: 0.03% (PL: 0.1%)
- Presence indicates bad drainage, bad management, high RH, high temp., and overcrowding
- High concentrations reduce body resistance and decrease animal health.
- At 40 ppm, it can harm chicks by affecting their eyes.
Carbon Monoxide (CO):
- Colorless, combines irreversibly with hemoglobin, and produces carboxyhemoglobin
- Higher than oxygen in binding to hemoglobin
- Source: Incomplete combustion of fuel materials
- Hygienic significance:
  - 0.06%: Harmful
  - Reaching 20% impairs locomotor control
  - 30%: Affects chemical changes in the body
  - 60%: Often fatal in animals
  - Common in pet animals but rare for farm animals
  - Symptoms include, but are not limited to hypoxia, lack of coordination, dyspnea, coma, and death (especially sudden)
Skatol and Volatile fatty acids (VFAs):
- Compounds from faulty drainage systems and animal waste

Temperature

Farm livestock are homeotherms, maintaining balance between heat loss and gain.
Heat Gain: Metabolism, Basal heat production, Digestive heat production, Muscular heat production, Solar radiation.
Heat Loss: Radiation, Convection, Conduction, Evaporation (Urine, faeces), Evaporation (sweat)

Dust

A significant environmental problem in Egypt due to its adjacent desert, dryness of the atmosphere, and lack of rain.
Types: Inorganic dust (lime salts, iron, silica, sodium chloride) and Organic dust (molds, fungi, bacteria, viruses).
Hygienic Significance: Upper respiratory tract irritation, lowered resistance to infections, lead/arsenic contamination causing poisoning in animals, especially in poultry.
Organic dust quantity may decrease with high RH%.

Other Factors (Summary)

Indoor Environment: Temperature, Relative Humidity, Air Velocity, Sunlight.
Animals: Density, Species, Sex, Health Status.
Management: Cleaning, Drainage system.
Floating Particles: Plant fibers, epithelial cells, feathers, pollen, etc.
Photoperiod: Time between sunrise and sunset, varying with altitude and season; impacting reproductive function and seasonal differences/differences in the onset of puberty in animals.
Light and Ovulation: Light transference to the neural signal to pineal body, releasing gonadotropins stimulating maturity.
Light and Rearing: Photoperiod for broiler and layer chickens (3-5, 5-7 Weeks, and 7weeks in broilers).
Temperature: Affecting growth, productivity, heat stasis, and chilling diseases.
Protection Against Hot Environment: Cold water, green fodder, cold bathing, shaded shelter, clipping (for sheep).
Prevention of Cold: Concentrate feeding, exercise, sufficient cover and bedding.
Wind-Borne Diseases.
Air Movement: Rate air moves over skin, affecting heat loss (convection).