A new study published has found nearly eight out of 10 girls in Karnali, a province in western Nepal where the practice is prevalent, were banished from their homes while menstruating.

Because menstruating girls and women are viewed as impure, many have to sleep in huts, where they are at risk of being raped, bitten by snakes or dying from carbon dioxide poisoning from fires lit to keep warm.

In many communities, women and girls having their period are not allowed to meet other family members or venture out, must eat frugally, and are barred from touching a range of items including milk, religious idols and cattle.

"The women and girls we spoke to were terrified of snakes and animals coming in at night, or of being attacked by strangers," said Jennifer Thomson, who worked on the study, published in the journal Sexual and Reproductive Health Matters.

The centuries-old Hindu practice known as chaupadi was outlawed in 2005, but penalties including a fine and jail time were only introduced last year after the deaths of a teenager and a mother and her sons.

Researchers interviewed 400 girls in mid-Western Nepal's Karnali province for the study and found 77 per cent were subjected to chaupadi despite the ban.

Activists say more needs to be done to raise awareness and combat the perception that menstruating women and girls are impure and can bring misfortune on their communities.

"An integrated approach of health and education must be reached to every household and educate people that menstruation is a biological process and it does not make women impure," said women's rights campaigner Radha Paudel.

Australian Associated Press