"It is very hard to manage now that it is so cold. We sleep on an open verandah at our host's home because he has only two rooms indoors and these are occupied by his own family of 10," said Waris Mehsud, aged 35.
He was displaced from South Waziristan in November when the government's military operation against militants intensified. He now lives with relatives in Dera Ismail Khan town, NWFP. "Two of my four young children are sick with high fever and bad colds and it is hard to keep them warm at night," he said.
An acting UN Refugee Agency (UNHCR) spokesperson told IRIN last week that up to "900,000 people could still be displaced, most of whom remain with host families". Estimating the number of IDPs outside camps has been hard as many of them move between their homes in conflict zones and their hosts in other areas, the spokesperson said.
"We thought about going back earlier this month because our hosts were under strain because of us, but our home near Wana, [in South Waziristan] has been damaged and we cannot move back until repairs are carried out," said Mehsud.
In addition to IDPs living with hosts, UNHCR says there are 110,368 IDPs in 13 camps - in Peshawar, Nowshera, Mardan, Charsadda, Lower Dir and Hangu districts. Most are from Bajaur Agency.
"Winterization packages", including all-weather tents, blankets and plastic sheets, have been distributed to these IDPs but living conditions are still hard, according to an update by the Office for the Coordination of Humanitarian Affairs (OCHA) covering 26 November to 9 December 2009.
To keep warm some IDPs have tried to light fires very near their tents, or even inside them, and "we have had to stop them because it is dangerous," said Muhammad Husain, an organizer for the local authorities in Hangu District, where a camp has been set up in the town of Muhammad Khoja.
Two weeks ago, four children were burnt to death after a tent caught fire at Jalala Camp in Mardan District, due to an electrical short circuit.
Tough for women, children
Life is especially tough for women and children.
"It is very hard to wash clothes or bathe the children because there is no hot water, and we cannot heat more than a small pan on our stoves," Zareen Bibi, a displaced woman living in Muhammad Khoja Camp with some 50 other families, told IRIN.
There are also unexpected problems: "Now that it is winter, the men from our host family sleep indoors instead of in the courtyard. We can only reach the toilet if we pass through the room where my cousin and his adult sons sleep, and this is not appropriate. Sometimes my two teenage daughters and myself cannot relieve ourselves for over 14 hours, until the men leave the room," said Uzma Bibi, 40, in Mardan.
"Upper respiratory tract infections are common in children at this time of the year. Children are especially vulnerable, and there have been reports of sickness among child IDPs," Maheen Khan, a pediatrician in Peshawar, said.
Insecurity has hampered access to IDPs by both international agencies and female health professionals.