Particulate matter

This section provides monitoring data on particulate matter (PM₁₀ and PM_2.5) levels in Aotearoa New Zealand, including long-term exposure (annual averages) and short-term exposure (daily levels). Concentrations are measured against the National Environmental Standard for Air Quality (NESAQ) and WHO guidelines for PM exposure. 

National Environmental Standards for Air Quality (NESAQ) for PM and WHO guidelines have been developed to provide some level of protection against health risks - though the WHO guidelines lack any regulatory weight in New Zealand. However, currently, there is no evidence for a threshold below which health effects do not occur [1]. Moreover, at this time, New Zealand does not have a national standard for PM_2.5.

What is particulate matter?

The most significant impacts on human health from air pollution are due to exposure to particulate matter (PM). PM consists of small airborne particles, including solid matter and liquid droplets. PM can affect more people than any other pollutant and the relationship between health impacts and PM air pollution is therefore well researched [1].

PM_2.5 refers to particles with a diameter of less than 2.5 micrometres (Figure 1). These particles are mainly produced by combustion of fossil fuels (eg, motor vehicle emissions, burning wood and coal for home heating) and through transformation of other particles such as NOx, SO₂, and organics.

PM₁₀ refers to particles with a diameter of less than 10 micrometres, which is the major air pollutant monitored in New Zealand (Figure 1). These particles are derived primarily through suspension of dust and soil and other materials from roads, farming, construction, mining activities, and coal and oil combustion. PM₁₀ also includes sea salts, mould, pollen and other plant parts [1, 2].

PM increases the risk of respiratory illness

Coarse particles such as PM₁₀ deposit in the upper airways, whereas smaller particles such as PM_2.5 deposit in the very small airways deep in the lungs [2].

Short-term and long-term exposure to PM₁₀ and PM_2.5 is associated with a wide range of health impacts. Mild impacts include shortness of breath or coughing. More severe impacts include premature death from cardiovascular and respiratory problems and an increased risk of lung cancer. Exposure to PM₁₀ can also worsen asthma symptoms. Exposure to PM_2.5 is associated with asthma, diabetes and adverse birth outcomes such as low birth weight, preterm birth and small-for-gestational-age births [1, 3].

Children, the elderly, and people with pre-existing conditions such as cardiovascular or respiratory diseases are particularly vulnerable to health impacts from PM air pollution [3].

Read more on the health effects of air pollution webpage.

Standards and guidelines

National Environmental Standards for Air Quality (NESAQ) for PM [1] and WHO guidelines [3] have been developed to provide some level of protection against health risks. However, currently there is no evidence for a threshold below which health effects do not occur [1]. Moreover, at this time, New Zealand does not have a national standard for PM_2.5.

Information about the data

Particulate matter (PM₁₀) – annual average and daily values

Source: Ministry for the Environment –  Our Air 2021

Definition: Number of monitored sites that exceeded the WHO annual average guideline for PM₁₀ (exceedances occur when annual average concentrations are greater than 15µg/m³) and number of monitored sites that exceeded the national environmental daily (24-hour) average standard for PM₁₀ (exceedances occur when daily average concentrations are greater than 50µg/m³; one exceedance per 12-month period allowed).

Particulate matter (PM_2.5) – annual average and daily values

Source: Ministry for the Environment –  Our Air 2021

Definition: Number of monitored sites that exceeded the WHO daily (24-hour) average standard for PM_2.5 (exceedances occur when daily average concentrations are greater than 15µg/m³) and number of monitored sites that exceeded the WHO annual average guideline for PM_2.5 (exceedances occur when annual average concentrations are greater than 5µg/m³).