Environmental Engineering Reference
In-Depth Information
(e.g., after a manhole cover has been removed or a basement door opened). Carbon dioxide is
colorless and odorless and therefore not readily detectable. Carbon dioxide concentrations of
10% or more can cause unconsciousness or death. Lower concentrations may cause headache,
sweating, rapid breathing, and increased heartbeat, shortness of breath, dizziness, mental
depression, visual disturbances, and shaking. The seriousness of these symptoms depends on
the concentration and duration of exposure. The response to carbon dioxide inhalation varies
greatly even in healthy normal individuals.
In assessing the public health issues of migrating landfill gas, environmental health
professionals should investigate the presence of buried utility lines and storm sewers on or
adjacent to the landfill. These structures not only provide a pathway for migrating gases, but
also pose a special asphyxiation problem for utility workers who fail to follow confined space
entry procedures prescribed by OSHA. On-site or adjacent residences and commercial
buildings with basements or insulated (or sealed) crawl spaces should also be investigated for
potential asphyxiation hazards.
3. Landfill odors
Landfill odors often prompt complaints from community members. People may also have
concerns about health effects associated with these odors and other emissions coming from
the landfill. People in communities near landfills are often concerned about odors emitted
from landfills. They say that these odors are a source of undesirable health effects or
symptoms, such as headaches and nausea. At low-level concentrations—typically associated
with landfill gas— it is unclear whether it is the constituent itself or its odors that trigger a
response. Typically, these effects fade when the odor can no longer be detected. Landfill gas
odors are produced by bacterial or chemical processes and can emanate from both active and
closed landfills. These odors can migrate to the surrounding community. Potential sources of
landfill odors include sulfides, ammonia, and certain NMOC, if present at concentrations that
are high enough. Landfill odors may also be produced by the disposal of certain types of
wastes, such as manures and fermented grains. The following are major landfill gases
generated:
Sulfides
.
Hydrogen sulfide, dimethyl sulfide, and mercaptans are the three most common
sulfides responsible for landfill odors. These gases produce a very strong rotten-egg smell—
even at very low concentrations. Of these three sulfides, hydrogen sulfide is emitted from
landfills at the highest rates and concentrations. Humans are extremely sensitive to hydrogen
sulfide odors and can smell such odors at concentrations as low as 0.5 to 1 part per billion
(ppb). At levels approaching 50 ppb, people can find the odor offensive. Average
concentrations in ambient air range from 0.11 to 0.33 ppb. According to information collected
by the Connecticut Department of Health, the concentration of hydrogen sulfide in ambient
air around a landfill is usually close to 15 ppb.
Ammonia.
Ammonia is another odorous landfill gas that is produced by the
decomposition of organic matter in the landfill. Ammonia is common in the environment and
an important compound for maintaining plant and animal life. People are exposed daily to
low levels of ammonia in the environment from the natural breakdown of manure and dead
plants and animals. Because ammonia is commonly used as a household cleaner, most people
are familiar with its distinct smell. Humans are much less sensitive to the odor of ammonia
