Pure, clean air is best for maintaining good upper respiratory health. Bad smells are an indication that a contaminant is present. If the smell of raw sewage or sewer gas is present, it's possibly a sign of a health hazard. The health hazards of inhaling the smell of raw sewage are not likely an immediate threat, but it's still a good idea to resolve the issue. Contact with contaminants and bacteria is a cause of illness.
Sewer gas is a term for hydrogen sulphide gas, which is detected as a smell similar to rotten eggs. Sewer gas is colourless, but has a strong odour. It is a natural byproduct of the breakdown of waste material. Its presence signals a malfunctioning sewer venting system. Sewer drains by dry taps sometimes allow sewer gas to enter a home or other enclosed space. Smelling sewer gas at low concentrations is not deadly, but it does cause eye and throat irritation, coughing and trouble breathing. Long-term effects of inhaling low concentrations of hydrogen sulphide gas include fatigue, loss of appetite and headache. Extremely high concentrations of the gas are toxic and sometimes fatal.
In open areas where raw sewage is present, the unpleasant smell is likely the worst effect, assuming there is no long-term exposure. Particles of raw sewage are able to become airborne, however, and inhalation of these particles causes adverse health effects such as gastrointestinal discomfort, diarrhoea, nausea and vomiting. Raw sewage poses the biggest threat to public health when it enters the water supply, where it is diluted and spread much wider than where it originated. While boiling water before consuming it minimises the risk of waterborne illness, there is a high risk of potentially deadly diseases such as cholera and dysentery from drinking water contaminated with raw sewage.
Contaminants and Diseases
Exposure to raw sewage poses several health threats. People who come into contact with raw sewage need to get tetanus boosters as needed, usually once every 10 years. Parasitic worms frequently present in sewage cause leptospirosis, which is transmitted chiefly by rats. Hepatitis A results from ingesting water or food prepared with water contaminated with raw sewage.
In 2007, rumours circulated about the hallucinogenic effects of directly inhaling a strong concentration of human waste material that had been allowed to "ferment" in containers for a certain amount of time. This rumour was exacerbated by the Internet, and the story was picked up by major news outlets in the United States. The rumour was later proven to be a hoax, and the hallucinogenic properties of inhaling raw sewage have not been investigated or confirmed.