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  • Particulates are liquid or solid particles fine enough to be suspended in the air. They may be naturally formed – for example, in Canterbury, two sources are sea spray and dust blown off the Canterbury plains. They can also be artificially produced, especially as a result of burning. Most particulates are produced by motor vehicles, particularly diesel engines, or wood burners. Industry can also release particulates into the air.

    Rights: EPA, United States Environmental Protection Agency

    Size comparisons for PM particles

    Particulate matter (PM) is made up of liquid droplets and solid particles fine enough to be suspended in the air. The smaller the particle the deeper it can travel into a person's lungs. Here particulate sizes are compared to the width of a human hair.

    The smaller particulates cause the most health problems. You breathe in particulates with the air that you breathe. The larger particulates get caught in your mucus membranes before they reach your lungs, but the smaller particulates can make it all the way to your lungs and the smaller they are, the further they go. The particulates that make it to the lungs are 10 microns or less or about 1/7 of the width of one of your hairs. These are known as PM10 particulates.

    Air pollution study

    Professor Simon Kingham explains how he has been asked by the government to estimate some of the costs of air pollution – how it affects people’s health and may cause them to die, to need time off work because they are sick or to go to hospital for medical treatment.

    Associate Professor Simon Kingham is a researcher in the Geography Department at the University of Canterbury. He is researching the links between transport, woodburners, pollution, and health. Scientists like Simon Kingham are interested in measuring them and comparing levels of PM10 to levels of ill health in different areas. Also of interest are even finer particles that are 2.5 microns or less, known as PM2.5, which can make it even further into your lungs.

    Ill health and pollution

    Associate Professor Simon Kingham talks about how there is an association between the level of air pollution and people’s health.

    The particulates can cause respiratory illnesses because they block the small tubes that carry air into lung tissue. People who are more at risk from particulates are children, the elderly and people who already have breathing problems such as asthma or bronchitis. Your body responds to particulates in your lungs by producing mucus, which you have to cough out. They also place your body under stress, which may lead to cardiovascular illness.

    Christchurch pollution problem

    Professor Simon Kingham talks about the high level of particulate air pollution in Christchurch, which can cause people who are already at risk of respiratory illness to die.

    Where the particulates come from is really important. The particulates that are formed naturally are not so much a problem because your immune system can deal with most of them. When there are additional particulates, such as those formed as a result of burning, your system may be overloaded and not cope, so you do not breathe as well. When materials are burned, they can form toxic molecules that may cause cancer, so particulates can make you really sick.

    Pollution exposure

    Professor Simon Kingham discusses how the amount and type of air pollution you are exposed to depends on where you live, what sort of heating is used in your house and how you get to school or work.

    You might like to find out how scientists measure the particulates in the air. How do we know that it is the particulates that cause respiratory illnesses?

    Activity ideas

    Try out this activity in which students investigate exhaust emissions, car use and air quality.

    Global Earth Challenge is an international citizen science project that has a section on monitoring air quality.

    Related content

    The 2017 Connected article Sensing data describes how a team of researchers used technology and big data to help make Christchurch a healthier smarter city to live in.

    This article uses Ururangi, a whetū in the Matariki cluster, to consider the state of air quality in Aotearoa.

    The Clear the air collection supports the House of Science Clear the Air resource kit – but it is also useful for anyone interested in the human respiratory system and air quality/air pollution.

    Useful links

    See The Ministry for the Environment’s environmental section on air for a variety of information. For latest Environment Aotearoa reports see the air section.

    See our Pinterest collection on Air quality for a range of useful resources.

      Published 8 January 2009, Updated 19 October 2018 Referencing Hub articles
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