Indicators at a glance - indoor environment

This section summarises the latest Environmental Health Indicators about the indoor environment and health in New Zealand. 


A poor indoor environment can affect our health through a range of ways.

  • Household crowding increases the risk of infectious diseases.
  • Second-hand smoke exposure can cause asthma, lower respiratory tract infections, sudden unexpected death in infancy (SUDI), middle ear infection and low birth weight in children, and ischaemic heart disease, stroke and lung cancer in adults. 
  • Cold, damp, mouldy housing can worsen asthma, and is associated with asthma onset and respiratory tract infections.  

Young children and the elderly are particularly at risk from the effects of poor housing.

Indicator Key findings
Household crowding
  • About 366,000 New Zealanders (10%) lived in a crowded household in 2013. This included almost 131,000 children aged 0–14 years (about 15% of children).
  • Household crowding rates have decreased since 1991.
  • People of Māori and Pacific ethnicity were the most affected by household crowding in 2013.
Second-hand smoke exposure
  • The percentage of mothers who smoked at two weeks postnatal has decreased from 13.7% in 2009 to 9.4% in 2018. Maternal smoking rates were highest among Māori mothers in 2018 however their smoking rates have declined since 2009.
  • In 2015/16, about 29,000 children (3.2%) and were exposed to second-hand smoke in their home. A similar prevalence was reported among non-smoking adults.
  • The rates of second-hand smoke exposure had more than halved since 2006/07. 
  • Children living in the most deprived areas were 18 times as likely to be exposed to second-hand smoke in the home than those in the least deprived areas.
  • In 2018/19, about 110,000 children aged 2–14 years had asthma and were taking medication for it. The asthma rate had decreased from 16.6% in 2015/16 to 13.1% in 2018/19. Rates of medicated asthma were higher among boys, and Māori and Pacific children.
  • In 2018, there were 7,182 hospitalisations for asthma among children aged 0–14 years. The asthma hospitalisation rate had increased since 2002. Asthma hospitalisation rates were highest among younger children (0–4 years), Pacific children, and children living in more deprived areas. 
Lower respiratory tract infections
  • In 2016, there were 9262 hospitalisations for lower respiratory tract infections among children aged 0–4 years. The hospitalisation rate had increased since 2001. The hospitalisation rate was higher among Pacific and Māori children, and among children living in more deprived areas.  
Sudden unexpected death in infancy (SUDI)
  • In 2017, 48 children aged under one year old died from SUDI, a rate of 0.8 per 1,000 live births. Since 2008, the SUDI rate has remained relatively steady.
  • In 2013–17, SUDI rates were higher among Māori and Pacific babies, babies of younger mothers, and among babies living in the most deprived areas.   
Meningococcal disease
  • In 2018, there were 46 notifications (out of 120) of meningococcal disease in children aged 0–14 years. 
  • The rate of meningococcal notifications has doubled since 2014.
  • Meningococcal Group B continues to be the most dominant strain in children.
  • The highest notification rates were in infants, Māori children, Pacific children, and children living in the most deprived areas.  
Health burden due to second-hand smoke
  • In 2010, an estimated 104 people died from second-hand smoke exposure in New Zealand. 
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