Johannesburg – The South African National Blood Service (SANBS) has warned that it was experiencing critical blood shortages and that November was going to be "a testing month".The SANBS revealed on Wednesday that it was experiencing critical shortages because it wasn’t able to hold blood drives at schools and universities across the country during the end of year examinations.It said there were only 1473 units of blood-type O in stock, or just about one and a half days of O type, while the situation in KwaZulu-Natal seemed dire with less than one day's supply of blood available."The blood supply in the province is currently at 0.7 days of stock (129 units), compared with a [usual] healthy blood stock for KZN of 500 units," the SANBS said.It said Gauteng had about one and a half days of blood in stock, while the Free State and the Northern Cape had just a little more.The SANBS said it was considered a ''crisis'' when blood stocks dipped below two days of stock available.The SANBS' national marketing manager, Silungile Mlambo, described the shortages as "dangerously low"."The situation has, in fact, reached a critical level in KwaZulu-Natal and we appeal to all South Africans – active donors, lapsed donors and potential donors – to go to their local donor centre and donate blood to bolster the national blood stock," Mlambo said."So many people in life-threatening situations require blood. It’s what saves a haemorrhaging mother's life so that she can raise and love the baby she has just brought into the world. It's what saves someone suffering complications during major surgery. It's what helps cancer patients endure and survive treatment," she said.Mlambo said the SANBS appealed to South Africans to donate blood immediately."More than that, however, we appeal to South Africans to become regular donors. By donating blood only four times a year, we can easily avoid situations such as the one in which we find ourselves," she said.