BULGARIAN
Many of you will have heard people talk about PM10 and PM2.5, but what exactly is it and why should it be measured?
What is particulate matter (PM)?
Particulate air pollution is defined by the US EPA as an air-suspended mixture of both solid and liquid particles. They are often separated into three classifications; coarse, fine and ultrafine particles. Coarse particles have a diameter of between 10 µm and 2.5 µm and settle relatively quickly whereas fine (1 to 2.5 µm in diameter) and ultrafine (<1 µm in diameter) particles remain in suspension for longer. Keep in mind that due to how the scale is built, PM10 (coarse) also automatically contains PM2.5 (fine) and PM1.0 (ultrafine). Additionally, PM2.5 (fine) contains PM1.0 (ultrafine) as well. To put things into perspective, human hair has a diameter of 50-70 µm and a grain of sand has a diameter of 90 µm.
When someone talks about PM10 they are referring to particles smaller than 10 µm. These particles include dust, pollen and mold spores. Conversely, when someone references PM2.5 they are referring to particles smaller than 2.5 µm. These smaller particles include combustion particles, organic compounds and metals.
What is the best way to measure particulate matter?
Here at Aeroqual we have our own range of high-quality instruments that will measure and report on PM levels.
Aeroqual helps organizations successfully measure PM2.5 and PM10. Below are just some of the examples:
- Tonglu (China) Environment Protection Agency required an expansive network of monitoring stations that accurately viewed and measured the levels of PM2.5 across the entire county.
- Colgate University needed a research-grade PM sensor for their new laboratory module focused on air pollution, specifically Particulate Matter (PM) and Ozone.
- Environmental Resources Management, Inc (ERM) required reliable offshore monitoring, that could operate with little (human) intervention, fit within a compact environment and did not have high power requirements.
Where does particulate matter come from?
Particulate matter can come from both human and natural sources. Natural sources include sea salt, forest fires, pollen and mold. As they are natural occurrences, they are harder to control and are usually left unregulated. Human sources, however, can be regulated and understanding where PM comes from is very important. PM10 is most associated with road dust and construction activities. Wear and tear of brakes and tyres on vehicles and crushing activities at construction sites can all contribute to a rise in PM10. Alternatively, PM2.5 is more associated with fuel burning, industrial combustion processes and vehicle emissions.
Why should we measure ambient particulate matter?
The growing awareness of both PM10 and PM2.5 is largely associated with the potential damaging effects they can have on the human body. The World Health Organisation (WHO) believes particles are affecting more people worldwide than any other pollutant.
Primary health effects include damage to the respiratory and cardiovascular systems. Due to the small size of PM10 and PM2.5 particles, they can penetrate the deepest parts of the lungs as well as access the gas exchange regions of the lung via diffusion.
It is important to note that the duration of exposure is also a significant factor to consider, as even short-term exposure to particulate matter can have detrimental effects on the body.
As a result of the damaging health effects from PM10 and PM2.5 the WHO recommend the following exposure limits:
These guidelines can be hard to follow, and many authorities do not meet the limits above, for example, the United States and Europe have much higher PM10 exposure thresholds. Governments must weigh up the potential damage to population health with the cost of reducing particulate concentrations. A great first step to understanding the seriousness of the issue is to monitor PM.
It is worth also mentioning larger particles (above 10 µm). These sized particles are not usually acknowledged in government health legislation as they can be filtered out in the nose and throat. Instead, they are known as a nuisance rather than a health risk. Total Suspended Particles (TSP) is the term used when referring to larger particles. TSP does not have a specified size limit and therefore covers the full range of particle sizes. It is common for TSP to be measured alongside PM10 and PM2.5, particularly at industrial sites where nuisance dust assessment and monitoring is becoming more frequent. It is worth noting that the EPA previously legislated TSP and by previous definition, TSP was the term to mean particulate air pollution.
Who should be monitoring particulate matter?
Heavily urbanised areas where there are high traffic volumes coupled with high population densities are most at risk. It is estimated that the largest city in China, Shanghai, has approximately 6.3 million residents exposed to PM at levels that exceed WHO guidelines.
Many countries have legislation that require ambient PM monitoring in cities. Roadside monitoring, which is a more specialist activity, is commonly used by governments and local authorities to measure PM levels in cities to ensure legislation is met. For further information on roadside monitoring please have a look at our roadside application page which links to case studies and a range of monitoring instruments that can be used to measure PM10, PM2.5, TSP and other air pollutants commonly found at the roadside.
