Home energy efficiency and radon related risk of lung cancer: modelling study

Abstract

Objective: To investigate the effect of reducing home ventilation as part of household energy efficiency measures on deaths from radon related lung cancer.

Design: Modelling study.

Setting: England.

Intervention: Home energy efficiency interventions, motivated in part by targets for reducing greenhouse gases, which entail reduction in uncontrolled ventilation in keeping with good practice guidance.

Main outcome measures: Modelled current and future distributions of indoor radon levels for the English housing stock and associated changes in life years due to lung cancer mortality, estimated using life tables.

Results: Increasing the air tightness of dwellings (without compensatory purpose-provided ventilation) increased mean indoor radon concentrations by an estimated 56.6%, from 21.2 becquerels per cubic metre (Bq/m(3)) to 33.2 Bq/m(3). After the lag in lung cancer onset, this would result in an additional annual burden of 4700 life years lost and (at peak) 278 deaths. The increases in radon levels for the millions of homes that would contribute most of the additional burden are below the threshold at which radon remediation measures are cost effective. Fitting extraction fans and trickle ventilators to restore ventilation will help offset the additional burden but only if the ventilation related energy efficiency gains are lost. Mechanical ventilation systems with heat recovery may lower radon levels and the risk of cancer while maintaining the advantage of energy efficiency for the most airtight dwellings but there is potential for a major adverse impact on health if such systems fail.

Conclusion: Unless specific remediation is used, reducing the ventilation of dwellings will improve energy efficiency only at the expense of population wide adverse impact on indoor exposure to radon and risk of lung cancer. The implications of this and other consequences of changes to ventilation need to be carefully evaluated to ensure that the desirable health and environmental benefits of home energy efficiency are not compromised by avoidable negative impacts on indoor air quality.

Fig 1 Modelled present day and future ventilation rate distributions of English housing stock. Scenario 1=air tightness; scenario 2=air tightness+purpose-provided ventilation; scenario 3=as for scenario 2+mechanical ventilation and heating recovery (MVHR); scenario 4=as for scenario 3+10% failures in MVHR

Fig 2 Proportions of current housing stock and attributable burden of radon related lung cancer mortality for different levels of radon

Fig 3 Change in life years lived in population (relative to baseline) over time for each scenario. Negative figures indicate loss of life years. Scenario 1=air tightness; scenario 2=air tightness+purpose-provided ventilation; scenario 3=as for scenario 2+mechanical ventilation and heat recovery (MVHR); scenario 4=as for scenario 3+10% failures in MVHR

Fig 4 Additional deaths per year (relative to baseline) over time for each scenario and for different age groups. Scenario 1=air tightness; scenario 2=air tightness+purpose-provided ventilation; scenario 3=as for scenario 2+mechanical ventilation and heat recovery (MVHR); scenario 4=as for scenario 3+10% failures in MVHR. Note changes of scale on y axes

Fig 5 Mean radon level and space heating demand due to ventilation heat losses for the English housing stock plotted against ventilation rate, and current attributable health burden (annual life years lost assuming no lag) compared with annual greenhouse gas (GHG) emissions for space heating per 10⁵ dwellings