What is Particulate Matter?

Particulate Matter, also known as PM or Particle Pollution refers to extremly small solid particles and liquid droplets which are typically suspended in air. Particulate matter can be made up of a variety of compounds from soil or dust particles through to organic chemicals, metals and other compounds[1].

The size of the particulate matter can have a significant impact on its potential to cause health problems, and this is often how it is graded;

• PM10 refers to particles with a diameter of 10 micrometres or less, these are small enough to pass through the throat and nose and into the lungs. If inhaled these particles can have an impact on the heart and lungs [1].
• PM2.5 refers to particles with a diameter of 2.5 micrometres or less, these particles are so small that they can get deep into the lungs and subsequently into the bloodstream [1].

It should be noted that PM10 includes PM2.5 in its measurement, PM100 would include PM10 and PM2.5.

What are the National / International Limits?

Within Australia, the National Environmental Protection (Ambient Air Quality) Measure (NEPM) specifies that the Standard / Goal for outdoor Particulate Matter Pollutants is as follows [2];

• Particles as PM10,
  • 1 Day Average Limit; 50 micrograms per cubic metre of air,
  • Yearly Average Limit; 25 micrograms per cubic metre of air,
• Particles as PM2.5,
  • 1 Day Average Limit; 25 micrograms per cubic metre of air,
  • Yearly Average Limit; 8 micrograms per cubic metre of air,

Internationally, The World Health Organisation (WHO) specifies that the Standard / Goal for outdoor Particulate Matter Pollutants is as follows [3];

• Particles as PM10,
  • 1 Day Average Limit; 50 micrograms per cubic metre of air,
  • Yearly Average Limit; 20 micrograms per cubic metre of air,
• Particles as PM2.5,
  • 1 Day Average Limit; 25 micrograms per cubic metre of air,
  • Yearly Average Limit; 10 micrograms per cubic metre of air,

What is the concern around Particulate Matter?

The WHO goes on to state that it was estimated that in 2016, around 91% of the worlds population was living in places where the guidelines were not met. Ambient air pollution was estimated that air pollution in both cities and rural areas was estimated to cause 4.2 million premature deaths per year in 2016, with the mortality due to exposure to small particulate matter of 2.5 microns or less wihc cause cardiovascular and respiratory disease and cancers [3].

The WHO estimates that by reducing average annual PM2.5 concentrations from 35 micrograms per cubic metre of air (common in many developing countries) to the WHO guideline value of 10 micrograms per cubic metre of air this could reduce pollution related deaths by around 15%. It was also noted that even in the EU, where cities do comply with guideline levels, estimates suggest that the life expectancy is 8.6 months less than it could be due to PM exposure from human sources [3].

Whilst NEPM, and WHO provide limits, it should be noted that these limits do not imply that a level is “Safe” as it is below the guideline limit. In commentary to the Public Health Association of Australia, Adrian Barnett references the WHO air quality guidelines which state “there is little evidence to suggest a threshold below which no adverse health affects would be anticipated” [5].

Does Particulate Matter have an impact on productivity?

Whilst the above limits have largely looked at impacts on health, a number of studies have also investigated the link between PM and productivity and found that an increase inm PM2.5 by around 10 micrograms per cubic metre of air sustained over around 25 days reduced daily output by 1 percent [4] whilst many of these are non-service related industries it is suspected the impact will be similar across industries.

Within the indoor environment, there are two standards I am aware of (there may however be others) which have limits or ratings for particulate matter;

• WELL Building Standard[6]
  • PM10 should be less than 50 micrograms per cubic metre of air
  • PM2.5 should be less than 15 micrograms per cubic metre of air
• National Australian Built Environment Rating System (NABERS) Indoor Environment [7]
  • NABERS takes a slightly different approach in that the PM10 value is considered when calculating the air quality component of the rating, the lower the rating the better the score (all things being equal).
  • That said, a PM10 concentration of around 20 – 25 gives a score of near zero percent.

Endnotes:

[1] https://www.health.nsw.gov.au/environment/air/Pages/particulate-matter.aspx

[2] https://www.legislation.gov.au/Details/F2016C00215

[3] https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health

[4] https://www.sciencedaily.com/releases/2019/01/190103110735.htm

[5] https://onlinelibrary.wiley.com/doi/full/10.1111/1753-6405.12264

[6] https://standard.wellcertified.com/air/air-quality-standards

[7] https://www.nabers.gov.au/file/1336/download?token=zkaI5EUH