How clean is the Hunter Valley air?

The air quality in New South Wales’ Hunter Valley has made news this week, with serving and former politicians accusing one another of ‘cherry-picking’ data and misrepresenting information about how coal power stations pollute the air.

So, what is the air quality like in the Hunter – has it changed recently? And where can we find more information on it?

Air quality can be monitored in a few different ways, including from space. But the most accurate accounts come from on-the-ground reading. In Australia, this is managed by state departments and environmental protection agencies. Daily readings and predictions are available on a few websites, which is particularly of use to people with asthma and heart and lung conditions, who are more sensitive to pollutants in the atmosphere.

In NSW, air quality is monitored by the Department of Planning, Industry and the Environment.

“The NSW Government operates the largest air-quality monitoring network in Australia, with more than 90 monitoring stations across NSW,” says a spokesperson for the department. “This includes 14 air-quality monitoring stations in the Upper Hunter region.”

These stations are fitted with a range of instruments that measure various substances in the air. Most have PM₁₀ and PM_2.5monitors, which register how many particles are in the air that are smaller than 10 and 2.5 micrometres in diameter per cubic metre, respectively. These are the two most frequently used measures of air pollution. They’re measured using tapered element oscillating microbalances, which track particulates in the air by precisely monitoring how they hit a vibrating glass tube, changing its vibrations. 

Stations can also record specific pollutants like sulphur dioxide, nitrogen oxides, carbon monoxide, ozone, and ammonia, as well as wind and weather data.

Standardised instruments are used at each station, and data from each station can be freely obtained through the department’s website.

Has the air quality in the Upper Hunter improved recently?

NSW deputy premier John Barilaro has told the Guardian that “air quality in the Upper Hunter has improved over the past six months. Daily particle levels in Muswellbrook and Singleton have been within the national benchmark for 99% of the time during spring 2020”.

This is technically true. According to the Department’s seasonal reports, air quality has improved compared to spring and summer 2019–20. But those previous seasons saw drought and unprecedented bushfires, causing unusually high particle levels from dust and smoke. It’s unsurprising that the air is better 12 months later, in a much milder bushfire season – particularly since it’s been rainier.

“Air quality in the Upper Hunter and across NSW was greatly improved compared to the previous two years, as drought conditions weakened throughout most of NSW following good rainfall events from February 2020,” says a spokesperson from the department.

Particle levels in spring 2020 were comparable to levels recorded in 2011–17, without dramatic improvement.

It’s also worth noting that while Muswellbrook and Singleton each only recorded one day over the national benchmark for PM₁₀(50µg/m³) particulates in spring, the national policy aims to have no days above the benchmark annually, excluding ‘exceptional particulate events’: caused by bushfires, hazard reduction burns, or large dust storms. Background pollution and poor air quality are not considered reasonable exceptions.

How does the Upper Hunter compare to the rest of New South Wales?

The department also recognises that the Upper Hunter faces poor air quality from nearby coal mines and power stations.

“Air quality in 2020 varied across NSW regions, meeting national standards on 99% of days during the year on the Mid-north Coast, down to 85% of days at the Port of Newcastle. Historically, annual average PM₁₀ and PM_2.5 levels in the Hunter region have tended to be higher in some areas than elsewhere in the State, due to local industrial activities, such as the Port of Newcastle,” says a department spokesperson.

In a submission to the NSW Planning department opposing the expansion of a coal mine at Mount Pleasant, former prime minister Malcolm Turnbull used information from a 2018 report by the Australian Conservation Foundation, which listed the Hunter region as one of the most polluted postcodes in the area.

Turnbull also used the NSW’s publicly available monitoring system to point out dates when Muswellbrook and Singleton had particulate levels that exceeded the benchmarks.

“It is important to note that one of the consistent failures of the [Environmental Impact Statement on Mount Pleasant] is the lack of cumulative impact assessment (resulting from current and proposed mines) to inform proper decision making,” Turnbull told Cosmos. “This is contrary to the NSW Government’s own guidelines and policies.”