NIWA scientists test air quality in our kiwi homes


NIWA has a new invention for monitoring indoor air quality: PACMAN, a small box filled with air-quality instruments. This is a significant new tool that will help scientists understand pollutants that take the form of small airborne particles. It will help reveal where these particles come from, and our exposure to them in our homes.

PACMAN stands for Particles, Activity and Context Monitoring Autonomous Node. It is a small instrument package developed to continuously observe particles, carbon dioxide, temperature and movement at relatively low cost. PACMAN also has motion and distance sensors to identify activities of people in the home that influence indoor air quality.

In New Zealand, poor air quality is estimated to cause 730 premature deaths and cost over $1 billion dollars in restricted activity days per year. So far, most of the health research into air quality has been outdoors. Poor air quality impacts on the cardiovascular system and causes respiratory diseases. Different types of pollutants cause different health impacts.

"Exposure to pollutants can be much higher indoors than outdoors," says NIWA air quality expert Dr Guy Coulson. "We spend about 80 per cent of our time indoors, so we need to know more about indoor air quality." Initial measurements have shown that some activities, particularly cooking and using wood-burning stoves for heating, can lead to very high levels of indoor pollutants.

"We want to know if exposure to short lived, high levels of pollution are bad for you. Can one five minute exposure to very high levels of pollution have an impact on health?"

"PACMAN will be used to help us understand how many small airborne particles are in Kiwi homes, where they come from and what activities control their fate. In addition to the indoor sources, pollution from outdoors penetrates into most homes, even when doors and windows are shut," says Dr Coulson.

Toasting and cooking can be an intense source of airborne particles, along with incense, pesticides, heating, pets and evaporation from solvents. Cleaning products that are pine scented can also react with sunlight and produce particles.

"We are focusing on particles that get deep into your lungs. The highest measured concentrations have come from the poor use of wood-burning stoves or solid wood-burners."

Understanding air pollution in the home is difficult because everyone uses their home in a unique way.

"People are living in different atmospheres that they are creating, and breathing in different mixtures of particles. Working out how those mixtures are created and how they interact with each other, and with the surfaces in your home, will eventually lead to healthier homes," says Dr Coulson.

"We aim to be able to tell whether the pollution comes from inside or outside the house, and to see if neighbours' wood-burners are influencing your indoor air quality as well."

PACMAN has recently been tested in two Auckland homes. University of Canterbury PhD student Woody Pattinson became part of a living, breathing experiment for several months in a weatherboard 1960's style house in Waterview, Auckland. He had a roomful of instruments including PACMAN. He was cooking as part of the controlled experiment.

A short series of controlled tests were performed in the house aimed at testing specific questions around the PACMAN's performance. These included the ability to provide enough information to determine the source of indoor pollutants.

The tests alongside more expensive specialised instruments showed that PACMAN is a reliable tool for measuring indoor pollutant concentrations and can be used to distinguish indoor sources from outdoor sources.

Further work is required for the scientists to be able to use and interpret the data from PACMAN so that sources of indoor pollutants can be identified.

NIWA plans to build 15 or 20 PACMEN and put them in volunteers' homes, working with the equipment and the volunteers as part of the study. PACMAN is simple to use and unobtrusive, so it doesn't interfere with people's daily lives.

PACMAN was recently presented at the International Healthy Buildings 2012 Conference in Brisbane and generated considerable interest among the scientists gathered there.

PACMAN is part of an international online community involved in Open Source development of instruments and software for measuring and recording indoor air quality. The community consists of both researchers and participants working together to share resources and ideas.

You can even build your own PACMAN: it's been designed with open source hardware and software and the relevant files are available at

Join in, and be part of what could be the biggest indoor air quality experiment ever.

This research was funded by the Ministry of Business, Innovation and Employment.

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Air Quality Scientist
PACMAN stands for Particles, Activity and Context Monitoring Autonomous Node. Photographer NIWA Nick Talbot.
Nick Talbot cooking at his home in Mt Eden - PACMAN unit in foreground. Photo taken by Dave Allen on 6 Dec, 2012.
Nick Talbot cooking at his home in Mt Eden - PACMAN unit in foreground. Photo taken by Dave Allen on 6 Dec, 2012.