More than 600 Bay of Plenty pre-schoolers have been admitted to hospital and diagnosed with preventable respiratory illnesses in the past year, according to Ministry of Health data.
But one Tauranga doctor says the number of kids with those illnesses who do not reach hospital is actually in the thousands.
Ministry of Health statistics showed the leading cause of hospital admissions for children aged four and under was bronchiolitis, with 364 children diagnosed in the Bay of Plenty region.
The viral chest condition is preventable by washing hands before handling children and keeping them in smoke-free environments.
Respiratory diseases have also long been associated with cold, damp housing.
The total number of pre-schoolers diagnosed with preventable respiratory illnesses in Bay of Plenty in the past year was 619 - 133 had asthma, 111 had pneumonia, and 11 had bronchiectasis.
Dr Luke Bradford, from 5th Avenue Family Practice in Tauranga, said the number of children who did not reach hospital and instead were seen by GPs was in the thousands.
The 619 number was "the tip of the ice berg".
"It wouldn't be unreasonable for each working doctor to see five kids aged under five a week with these respiratory symptoms, and there are well over 100 GPs in the area," he said.
He estimated that in winter the number could easily reach 4000 or 5000 in the Bay.
Dr Bradford, also the co-chair of the Western Bay of Plenty Primary Health Organisation, said early assessment and ongoing monitoring and treatment by a GP would often avoid a worsening of the illness and decrease the chances of an admission to hospital.
"However, to truly improve the situation, work needs to be done on housing as we know incidence is higher in poorly ventilated, poorly heated, damp and overcrowded homes," he said.
Dr Bradford said education also needed to go into lessening children's exposure to cigarette smoke, both in the womb and in the wider world, "as these kids have more chance of having lungs which are more susceptible to these bugs".
He said immunisation was vital to reduce the cases of unnecessary and dangerous respiratory infections caused by pneumococcus, whooping cough and haemophilus influenza, all of which caused preventable admissions.
Dr Tony Farrell from Mount Medical Centre said this year had been particularly bad for respiratory viruses other than flu viruses.
"I have seen many cases over the past two months. I am aware that colleagues are concerned about the impact of overcrowding and homelessness on increasing communicable illness," he said.
"Any measures to improve warmth and ventilation of homes are paramount as well as hand washing and not going out to work if you are unwell."
Bay of Plenty District Health Board health equity/public health manager Brian Pointon said there was a well-known link between crowded, cold, damp, mouldy housing and respiratory infections in children.
The health board had a number of programmes in place to make an impact on unhealthy housing, one of which was designed to reduce rheumatic fever in children, he said.
He said there was also a second programme specifically aimed at reducing hospital admissions for pre-schoolers from bronchiolitis, meningitis and other respiratory infections.
Pregnant women could be referred so the housing could be improved before bringing a new baby home from the maternity ward.
- Research shows the risk of a cold and damp house can be reduced by keeping the house warm and dry with a well-insulated fabric, good ventilation systems, regularly opening windows and doors and heating the house in winter.
- Portable LPG heaters are also not recommended, as they release harmful gases and increase moisture levels in the home.