In small doses, breathing cat urine does not pose a risk to most people. However, in concentrated amounts found in poorly ventilated areas, ammonia fumes produced by cat urine can cause a number of serious symptoms after long-term exposure. These symptoms may include burning and watering of the eyes, coughing, wheezing, headache, and nausea, among others. The World Health Organization considers ammonia to be a possible carcinogen, meaning that inhalation of these fumes may be linked to cancer growth. Never clean up cat urine that has a strong ammonia smell with bleach; mixing bleach with ammonia will cause toxic gases to form.
In most cases, the effects of short-term exposure to cat urine inhalation are minor. The most common symptoms reported include headaches and burning, watery eyes. Occasionally, high concentrations of cat urine can cause nausea, vomiting, and dizziness. Children with asthma are most at risk for these symptoms. If a person feels these symptoms after exposure to cat urine, the quickest remedy is fresh air. If symptoms do not subside within an hour, call a physician or poison control.
Instances of long-term exposure to high levels of ammonia due to cat urine are very rare. Unsanitary, unkempt animal shelters and homes with a large number of cats living indoors are the few exceptions in which people may be at risk for long-term ammonia exposure. Ammonia is considered a possible carcinogen (may cause cancer) by both the World Health Organization and the U.S. Environmental Protection Agency. Long-term exposure to highly concentrated levels of ammonia can cause respiratory distress as well as nausea, vomiting, and dizziness.
Cat Waste and Pregnant Women
Contrary to what many people believe, breathing cat urine does not pose more of a threat to pregnant women than to other people. It is the possibility of contracting toxoplasmosis from cat faeces that poses the biggest risk for pregnant women. Toxoplasmosis is a disease caused by a parasite that most cats carry sometime during their lives. This disease is zoonotic--it can be transmitted from animals to humans. Pregnant women can pass this disease to the unborn child, who in turn could suffer a number of severe symptoms such as loss of hearing or vision, mental retardation, and, in some cases, death. The best prevention of the transmission of this disease via cat faeces is for pregnant women to avoid cleaning the litter box. People can also be exposed to toxoplasmosis through skin contact with soil and eating raw or undercooked lamb or pork.