Environmental Engineering Reference
In-Depth Information
need still, nutrient-rich water to breed, rice paddies are a prime habitat for the
insect; and, rice is a staple food in many mosquito endemic regions of the world.
IRRI has proposed village layout plans that optimally increase the distance to
mosquito-breeding grounds by relocating rice paddies to certain distances from
homes. They have also developed strains of rise that are resistant to pestilence,
resulting in less use of economic chemical poisons. Other projects include reduc-
ing methane and nitrous oxide emissions from burning of rice fields at the end
of the harvest season,
29
strategies for managing water scarcity in rice producing
areas,
30
and plans for increasing biodiversity in agricultural settings.
31
Commercial air circulation systems have been implicated in the spread of
infectious diseases. Legionnaires' disease is caused by the bacterium
Legionella
.
It was discovered when attendees at a military veterans' conference staying in
the same hotel came down with pneumonia. It was later found that the infec-
tious agent was spread via exhaled droplets that traveled through the ventilation
system.
32
,
33
Air filtration systems that are capable of sequestering airborne infec-
tious organisms are routinely used in developed nations, but more can be done
in developing countries to expand this prevention measure.
The spread of infectious diseases within a health care setting is called
nosoco-
mial transmission
. Transmission of infectious diseases in clinical care settings is
of grave concern because many hospitalized patients have compromised immune
systems, due to medications they are receiving, advanced age, or immune system
disorders. A large portion of nosocomial infections can be alleviated with frequent
hand washing by health care providers and proper barrier protection. However,
some factors influencing nosocomial spread can be alleviated through informed
design of hospitals, including air and water filtration systems and proper waste
disposal. For example, the shape of sinks in hospitals has been linked to transmis-
sion of
Pseudomonas aeruginosa
, a severe respiratory infection, often resistant
to drugs, that preferentially infects hospitalized patients. One study found that
faucets and taps were contaminated by the bacterium when water poured out from
drinking glasses splashed upward.
34
In Europe, there were reports of transmission
of smallpox from hospital workers breathing in aerosolized virus particles from
dirty laundry.
35
In these cases, simple engineering and process control measures
were enacted to end the outbreaks, alongside vaccination (when available and
appropriate).
The Centers for Disease Control and Prevention have issued four guidelines
for environmental infection control in health care facilities:
36
1. Appropriate use of cleaners and disinfectants;
2. Appropriate maintenance of medical equipment (e.g., automated endoscope
reprocessors or hydrotherapy equipment);
3. Adherence to water-quality standards for hemodialysis, and to ventilation
standards for specialized care environments (e.g., airborne infection isola-
tion rooms, protective environments, or operating rooms); and
4. Prompt management of water intrusion into the facility.
