Small intestine
It is approximately 1.5 cm in diameter in newborns after 35 weeks of gestational age, and 2.5–3 cm (1 inch) in diameter in adults. On abdominal X-rays, the small intestine is considered to be abnormally dilated when the diameter exceeds 3 cm. On CT scans, a diameter of over 2.5 cm is considered abnormally dilated. The surface area of the human small intestinal mucosa, due to enlargement caused by folds, villi and microvilli, averages 30 square meters.
Pit latrine
A pit latrine, also known as pit toilet or long drop, is a type of toilet that collects human feces in a hole in the ground. Urine and feces enter the pit through a drop hole in the floor, which might be connected to a toilet seat or squatting pan for user comfort. Pit latrines can be built to function without water (dry toilet) or they can have a water seal (pour-flush pit latrine). When properly built and maintained, pit latrines can decrease the spread of disease by reducing the amount of human feces in the environment from open defecation. This decreases the transfer of pathogens between feces and food by flies. These pathogens are major causes of infectious diarrhea and intestinal worm infections. Infectious diarrhea resulted in about 700,000 deaths in children under five years old in 2011 and 250 million lost school days. Pit latrines are a low cost method of separating feces from people.
A pit latrine generally consists of three major parts: a hole in the ground, a concrete slab or floor with a small hole, and a shelter. The shelter is also called an outhouse. The pit is typically at least three meters (10 feet) deep and one meter (3.2 feet) across. The hole in the slab should not be larger than 25 centimeters (9.8 inches) to prevent children falling in. Light should be prevented from entering the pit to reduce access by flies. This may require the use of a lid to cover the hole in the floor when not in use. The World Health Organization recommends the pits are built a reasonable distance from the house, balancing issues of easy access versus that of smell. The distance from water wells and surface water should be at least 10 meters (32 feet) to decrease the risk of groundwater pollution. When the pit fills to within 0.5 meters (1.6 feet) of the top, it should be either emptied or a new pit constructed and the shelter moved or re-built at the new location. Fecal sludge management involves emptying pits as well as transporting, treating and using the collected fecal sludge. If this is not carried out properly, water pollution and public health risks can occur.
A basic pit latrine can be improved in a number of ways. One includes adding a ventilation pipe from the pit to above the structure. This improves airflow and decreases the smell of the toilet. It also can reduce flies when the top of the pipe is covered with mesh (usually made out of fiberglass). In these types of toilets a lid need not be used to cover the hole in the floor. Other possible improvements include a floor constructed so fluid drains into the hole and a reinforcement of the upper part of the pit with bricks, blocks, or cement rings to improve stability. In developing countries the cost of a simple pit toilet is typically between US$25 and $60. Recurring expenditure costs are between US$1.5 and $4 per person per year for a traditional pit latrine, and up to three times higher for a pour flush pit latrine (without the costs of emptying). 
As of 2013 pit latrines are used by an estimated 1.77 billion people, mostly in developing countries. About 892 million people (12 percent of the global population), practiced open defecation in 2016, mostly because they have no toilets. Southern Asia and Sub-Saharan Africa have the lowest access to toilets. The Indian government has been running a campaign called "Swachh Bharat Abhiyan" (Clean India Mission in English) since 2014 in order to eliminate open defecation by convincing people in rural areas to purchase, construct and use toilets, mainly pit latrines. It is estimated that 85 million pit latrines have been built due to that campaign as of 2018. Another example from India is the "No Toilet, No Bride" campaign which promotes toilet uptake by encouraging women to refuse to marry men who do not own a toilet.