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Smoke, fire and Auckland's air quality

Clearing the air on smoke in the city

Published: 25 October 2019

We sat down with resource consents specialist Paul Crimmins to talk about air quality and clear the air on some misconceptions about smoke and air testing.

Firstly Paul, what’s your role at the council and what kind of air expert are you?

I work with the council’s resource consents team providing advice on air quality issues from a regulatory perspective across the region.  My role includes making sure that hazardous air pollutants in the outdoor air remain within the levels acceptable under national environmental standards and our own Auckland Unitary Plan, to minimise risks of health effects.

I know a bit about monitoring outdoor air quality as a result of my training and my work, but it’s not my main role. However, I’m really pleased to be helping out this week as teams from across the council are all pitching in on this response.

So, lets cut to the chase Paul, what’s in this smoke that has been swirling in the city centre?

That is the burning question. And also the most difficult one to answer. We’re getting used to watching the magic of film and television return detailed results from fancy labs in a flash. In reality, we can’t quite do that.

Firstly, people should always avoid breathing in or spending large amounts of time in smoky conditions.

We know that this smoke will contain a complex mixture of combustion particles similar to what you would find in any smoke, such as from home wood-burners or vehicle exhausts. When talking about the harmful aspects of smoke and air quality, we focus on particulate matter, particularly those particles that are small enough to be inhaled because these have an effect on health.

Ok, so tell us about the particulate matter that we would expect to find in smoke from a fire like this one.

We monitor two sizes of particulate – PM10 and PM2.5 . PM10, which also contains PM2.5, is particles that can be inhaled into the lungs. PM2.5 is very fine particles that can enter the bloodstream. These particles are really tiny, a couple of thousandths of a millimeter in size.

The complexity of the components in smoke means it’s not easy to measure or define the wide range of exact chemicals in the smoke, but – and this is based on World Health Organisation guidance and standards – it is best to use PM10 measurements as a proxy for determining the risks of smoke from this fire.

We also know that the roofing material in this fire contained treated timber and bitumen. Burning bitumen has similar smoke profile to the emissions you would get from a ship.

So, in short, we can’t categorically list all of the components that were in the smoke from the International Convention Centre Fire but we were concerned about the health risks of the smoke.

You talked about monitoring air quality in the region, how is this done?

We have a network of air quality monitors across the region, a few of which are in the central city. We’ve been monitoring City Centre air quality using a high accuracy reference monitor on Queen Street, which is backed up by indicative sensors at the corner of Victoria and Albert Streets, Symonds and Wellesley St and a new monitoring site at Customs St near Albert St.

Results showed that parts of the City Centre experienced poor air quality on Tuesday afternoon and during Wednesday due to the plume of smoke. The levels of PM10 and PM2.5 fluctuated based on the direction of the smoke plume (carried by wind conditions) and the stage that fire was at.

On Wednesday, PM10 readings at the Queen St and Victoria/Albert St monitoring sites exceeded the 24-hour average national standard. However, the Customs St and Symonds/Wellesley St monitors did not appear to be impacted by the smoke.

While this event created an unusually high spike in PM10 for Auckland, it’s important to note that poor air quality readings are unfortunately not uncommon in the City Centre, largely shown by elevated nitrogen dioxide levels from traffic. And some large cities around the world are unlucky enough to experience readings like this on a continuous basis.

What areas were affected by the smoke from this fire and how do people know whether they should be concerned or not?

We all know that smoke is carried by wind and therefore influenced by the weather conditions on the day.

The fire was contained in the block that is surrounded by Nelson and Hobson streets, and Victoria and Wellesley streets.

Wind direction largely remained consistent with very strong south-westerlies.  This meant that anywhere to the west of the Convention Centre was largely unaffected by smoke. The streets most impacted by the smoke plume were to the north-east of the fire. At the outset, smoke was rising fairly high and largely impacting high rise buildings. On Wednesday, the smoke was pushed down to have a greater impact at lower buildings and street level. 

Paul explains which areas experienced the worst of the smoke since Tuesday afternoon.

What should people do if smoke has entered their workplace or home?

If you haven’t already – and some people will have returned home or returned to work – we recommend you air out your building as thoroughly as possible.

Auckland Regional Public Health Service has posted some great advice on its website for people in the smoke-affected area.

Importantly, if your area was not affected by smoke, so if you didn’t see or smell smoke, you don’t need to do anything.

Airing out buildings will range from full cleaning of air conditioning and ventilation systems by building managers (and specialist contractors) before re-commissioning the systems, to just opening doors and windows in residential apartments. 

If you have any soot accumulated on surfaces, this should be wiped down.

Some places will continue to experience residual odours from smoke, especially where it’s impacted furnishings and this smell may be unpleasant and uncomfortable, but is unlikely to cause any ongoing health issues. If people are worried about their health, they should contact their GP or Healthline on 0800 611 116.

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