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Reducing COVID-19 transmission through increased ventilation


COVID-19 is predominantly transmitted indoors via exhaled aerosols with risk strongly influenced by ventilation. In most spaces ventilation practice is driven by energy conservation (keeping rooms warm or cool).

Improving ventilation in indoor spaces is a key strategy to prevent Covid-19 transmission, but it is unclear whether extensive messaging about this is changing behaviour or reducing transmission. 

Funded by the Ministry of Health, NIWA air quality researchers are carrying out research to understand ventilation behaviour and examine how well spaces used by our most vulnerable populations are, and could be, ventilated.

This New Zealand-specific research will take place in over 100 early childhood education centres (ECEs), aged care facilities (ACFs), marae and churches. These will be geographically concentrated in areas with high Māori and/or Pacific populations (who are particularly vulnerable to COVID-19) and selected in partnership with Kokiri Marae and Hapai Research.

Project objectives

  1. Use carbon dioxide (CO2) measurements to calculate ventilation levels and transmission risk in buildings used by those most vulnerable to the acute health effects of COVID-19 infection.
  2. Understand current ventilation behaviours and the reasons for these behaviours (including barriers), through occupant interviews.
  3. Implement an intervention to improve ventilation practice in these buildings through generic advice, air monitoring, tailored data-driven advice, and portable air cleaners (PACs).

Study methods

We are studying the effectiveness of low-cost improvements to ventilation practices – better use of windows, fans and air filtration) and assessing the effectiveness of these through ongoing air monitoring data. 

Air samples will be taken from study locations and polymerase chain reaction (PCR) analysis used to validate the link between improved ventilation and reduced levels of airborne virus. 

Expected outcomes

The research findings will add knowledge and impact in the following areas:

  • Changes in ventilation practices in a variety of building types to reduce the risk of COVID-19 transmission.
  • Identifying behavioural barriers to adopting changes and how they may be overcome.
  • Better understanding of how building ventilation affects disease transmission and inequities in infections, and how such inequities might be proactively reduced.
  • Reproducible guidance and processes to improve ventilation for all sectors of society across Aotearoa.

The key people who we expect to benefit from this project will be users of participating aged care facilities, early childhood education centres and other buildings. 

However, we expect findings from this research to also be applicable to users and managers of buildings. Our outcomes have potential to feed into the development of New Zealand-specific indoor air quality guidelines for the prevention of airborne infectious diseases.


Principal Scientist - Air Quality