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Association between home insulation and hospital admission rates: retrospective cohort study using linked data from a national intervention programme

BMJ 2020; 371 doi: (Published 29 December 2020) Cite this as: BMJ 2020;371:m4571

Linked Editorial

Housing as a public health investment

Rapid Response:

Insulation also saves lives by reducing wood stove pollution

Dear Editor,

Re: Association between home insulation and hospital admission rates: retrospective cohort study using linked data from a national intervention programme

This really interesting study found major health benefits of retrofitting insulation in New Zealand (NZ) homes.
Warmer, more comfortable homes (thanks to improved insulation) have other advantages.  They save lives by reducing the need for wood heating.  In NZ, 56% of all health costs of man-made air pollution were attributed to home wood heating  –  an estimated NZ$4,425 per wood heater per year.[1]

In 2005, NZ attempted to solve its pollution problem by introducing stricter wood stove standards than currently required anywhere else in the world.  Sadly, the efforts failed. Average real-life emissions of new wood stoves were almost 8 times worse than lab test measurements, with virtually no relationship between real-life and lab test emissions.[2]  The magnitude of NZ’s health problems was demonstrated by the ‘Growing up in NZ’ study, which reported a 7% increased risk of non-accidental hospital emergency presentations in children under 3 for every additional wood-heater per hectare.[3]

Similar health problems are now emerging in the UK.  Dr Nick Hopkinson, medical director at the Asthma UK and British Lung Foundation highlighted the seriousness of the issue in Jan 2021, saying: 'To protect yourself and others, especially children who are particularly vulnerable as their lungs are smaller and still developing, avoid buying a wood-burning stove or using an open fire if you have another source of fuel to cook and heat your home with’. [4]

Experience in NZ implies that the current UK proposals for new stove standards and dry fuel are unlikely to make any real difference.  The emissions limits for Eco-design stove (Table 2 of the Air Quality Expert Group’s Report[5]) are much higher than the 1.5 g/kg required since 2005 in all urban areas of NZ.

PM2.5 is the UK’s most health-hazardous air pollutant, associated with 32,900 premature deaths in 2018, five times worse than NO2 (6,000) and O3 (1,000).[6]  Domestic wood combustion accounted for just 5.7% of the UK’s PM2.5 emissions in 1990, compared to 38% in 2018.[7]  

Since 2014, UK PM2.5 emissions from all other sources fell by 5,746 tonnes (71.96 to 66.21 kt), but this was insufficient to offset the 6,492 tonne increase in wood stove emissions (34.18 to 40.68 kt), leading to 1,100 more PM2.5-related premature deaths in 2018 than 2016.[7] Yet only about 7.5% of UK households used wood heating in 2015 and only 2.5% used it as sole heating.[8]

Good choices depend on good advice.  Sarah MacFadyen, head of policy at Asthma UK said: ‘We also need to see politicians doing more to raise awareness on the health dangers of wood and coal burning as part of a national health campaign on toxic air so people can make the best choices for their own health as well as the health of others around them’.[4] 

Using a Defra-approved wood stove ‘nearly tripled harmful indoor pollution’.[9]  The researchers recommended a health warning at the point of sale for new residential stoves to indicate the risks posed to users.[10]

Given the above, and that wood smoke contains the same and very similar toxic chemicals to cigarette smoke, health professionals should ideally reinforce Asthma UK’s message not to use wood stoves by supporting policies to:  1) not allow new stoves to be installed because of their really high health costs – thousands of pounds per stove per year and 2) provide subsidies to remove existing wood stoves.

We now know of the strong links between PM2.5 pollution and increased risk of Covid-19, that alternatives such as electric heat pumps help slow down global warming and provide cheaper heating for everyone who buys firewood. Consequently 1) and 2) above would be a win-win-win for the entire community!

Dr Dorothy L Robinson

Additional Information
1. Robinson, D.L. Accurate, Low Cost PM2.5 Measurements Demonstrate the Large Spatial Variation in Wood Smoke Pollution in Regional Australia and Improve Modeling and Estimates of Health Costs. Atmosphere 2020, 11, 856.
2. AAQG. Health Cost of Allowing New Wood Heaters – over $3,000 per heater per year; Australian Air Quality Group. Available at: 2020.
3. Lai, H.K.; Berry, S.D.; Verbiest, M.E.A.; Tricker, P.J.; Atatoa Carr, P.E.; Morton, S.M.B.; Grant, C.C. Emergency department visits of young children and long-term exposure to neighbourhood smoke from household heating – The Growing Up in New Zealand child cohort study. Environmental Pollution 2017, 231, 533-540, doi:
4. Taylor, M. Avoid using wood burning stoves if possible, warn health experts. Guardian 1 Jan, 2021.
5. Air Quality Expert Group. The Potential Air Quality Impacts from Biomass Combustion. Available at: 2017.
6. EEA. European Environment Agency. Air quality in Europe — 2020 report. EEA Report No 09/2020. Available at:; 2020.
7. NAEI. UK emissions data selector. Available at (select domestic combustion). Available online: (accessed on 1 August 2020).
8. UK DECC. Summary results of the domestic wood use survey. Department of Energy & Climate Change. Energy Trends: March 2016, special feature article. Available at: 2016.
9. Carrington, D. Wood burners triple harmful indoor air pollution, study finds. 19 Dec. 2020.
10. Chakraborty, R.; Heydon, J.; Mayfield, M.; Mihaylova, L. Indoor Air Pollution from Residential Stoves: Examining the Flooding of Particulate Matter into Homes during Real-World Use. Atmosphere 2020, 11, doi:10.3390/atmos11121326.

Competing interests: No competing interests

04 January 2021
Dorothy L Robinson
Adjunct Senior Research Fellow, University of New England,