The authors built a theoretical model of indoor heat and mortality, using no new data or study population. It maps published outdoor exposure-response curves onto indoor temperature, using how regional indoor temperature varies with outdoor temperature. A proof shows that, above the heat threshold, the indoor curve is steeper whenever indoor temperature rises less than outdoor. In 616 English living rooms, the cited indoor-outdoor temperature slope was 0.40. A cited Chinese study found mortality above threshold rose 5.5% per 1°C indoors versus 3.0% outdoors. The proof assumes heat deaths act wholly through indoor exposure, and that indoor risk rises only above a threshold.
Why it is interesting: Impact studies of cooling buildings have assumed that indoor changes act like equal outdoor changes. This model suggests that assumption may misstate benefits, either way, depending on indoor temperature relative to its threshold.
Abstract — the authors' own words, CC BY
Most individuals spend the majority of their time indoors. However, epidemiological evidence of the association between heat and mortality is dominated by studies using outdoor temperature as a proxy for personal exposure. To demonstrate how an exposure-response relationship between indoor heat and mortality may relate to that between outdoor heat and mortality, we develop a novel mathematical modeling approach. This approachuses the relationship between regional daily average indoor and outdoor temperature to map the exposure-response relationship for outdoor heat, estimated by epidemiological studies, to indoor heat. Due to the modifying effect of buildings on heat exposure, we show that a change in indoor temperature may be associated with a greater change in mortality than an equal change in outdoor temperature. This has implications for researchers seeking to assess the health impact of changes in indoor heat exposure. Furthermore, it provides a new theoretical framework for interpreting potential differences in the temperature-mortality relationship of indoor and outdoor heat exposure in epidemiological studies.
Cite this item
BibTeX
Free sign-up. A digest of the new papers twice a week, grouped by domain.
Other drivers in Tomorrow's world
-
Innovation in treatment
Treatments that did not exist before — drugs, operations, devices — and whether they reach the people who would benefit.
4 this week -
Changing behaviour at scale
Whether new technology can change what people do at the scale of a population: apps, wearables, automated messages, digital programmes and platforms, and how far their effects last and reach.
2 this week -
Medicine at a distance
What wearables, remote monitoring and care at home add to how health is measured and delivered, and whether it shows in outcomes.
1 this week -
A changing climate
How air pollution, heat and cold affect deaths and survival, how the attribution is made, and how the balance is changing.
4 this week -
Slowing ageing itself
Whether anything yet slows ageing itself, rather than treating one disease at a time, and how we would know if it did.
2 this week
