3.4. Scanning Mobility Particle Sizer (SMPS)

What is obvious reasons? Cost, but you still want to do it. What is the second reason why you want to do it for, composition. So sometimes you want chemical composition, and you are getting a lot of material. So you are, again, you are looking at composition that composition will give you a lot of clues to where it is coming from just getting mass distribution is not enough, multiple sources may be giving it to you.

Understanding the chemical composition of particulate matter is crucial. While cost is a significant factor in choosing measurement methods, knowing the composition helps identify the sources of the particles. If we only look at mass distribution, we may not accurately determine where the particles come from, as multiple sources can contribute to similar mass readings.

Think of it like trying to understand where a particular smell is coming from in a kitchen. If you only identify the total smell without figuring out which ingredients are involved (like garlic, onion, or spices), you may not know which dish is being prepared.

What we call a source apportionment, we have source of apportionment... and the only way to do a correlation is you do PM 10 using the APS.

Source apportionment refers to identifying the different sources contributing to particulate matter in the air. It requires specific signals to accurately differentiate between sources. However, when signals are mixed, it complicates the correlation process. By using methods like the Aerodynamic Particle Sizer (APS), one can measure aerodynamic diameters, which help correlate size distributions with chemical compositions more effectively.

Consider a mixed drink where different ingredients create a unique flavor. To determine the flavor profile, you would need to analyze each ingredient separately rather than just sampling the final mixture. Similarly, to understand air pollution's sources, we need to break down the components rather than just look at the overall pollution levels.

So, there are further something called ultra-fine particulate matter these are particulate matter which are below it typically is 300 nanometers and below 500 nanometers in that size range.

Ultra-fine particulate matter is defined as particles that are very small, typically less than 300 nanometers. These particles are predominantly emitted from vehicles, particularly diesel engines, and they can originate from combustion processes. Understanding the size distribution of these particles is essential as they can have significant health implications due to their ability to penetrate deep into the lungs.

Imagine trying to catch dust in the air; the smaller the dust particle, the harder it is to detect. It's similar with ultra-fine particulate matter: due to their tiny size, they can easily enter the bloodstream and cause health issues, just as those tiny dust particles can go unnoticed yet still affect your breathing.

So electrical mobility, and the instrument that is used to make is called as a differential mobility analyzer.

Electrical mobility is a technique used to classify particles based on their charge and size. The Differential Mobility Analyzer (DMA) measures the mobility of particles. It does this by exerting a potential difference across two concentric cylinders, which influences the trajectory of charged particles based on their size. By varying the voltage, the instrument can selectively allow particles of a specific size to pass through.

Think of the DMA like a turnstile at a theme park that only allows people of a certain height to pass through. By adjusting the turnstile (changing the voltage), it ensures that only those who meet the height requirement (specific particle sizes) can enter the amusement area (be counted in the measurement).

So, that method of measurement called as a condensation particle counter (CPC)... based on that you can calculate the particle size distribution and back calculate, what is the particle size that is coming through.

The Condensation Particle Counter (CPC) is a method used to detect and measure smaller nanoparticles by allowing them to grow in size through condensation. The CPC exposes incoming particles to a vapor environment, allowing smaller particles to merge with the vapor and grow larger, making them easier to detect. This enables researchers to infer the original size distribution of the particles based on the sizes detected after condensation.

This process is akin to blowing air into a balloon. As more air is added, the balloon expands and becomes easier to see and measure. Similarly, small particles in the air can 'grow' in size so that we can measure them accurately with instruments designed for larger particles.

So, very complicated instrument, the entire thing is called as a scanning mobility particle sizer or SMPS very expensive instrument cost around 50 lakhs, 60 lakhs as you can imagine, but it is used a lot in trying to understand what is the distribution of particles all the way from 10 nanometers up to 10 microns.

The Scanning Mobility Particle Sizer (SMPS) is a sophisticated and expensive instrument used to measure particle size distributions ranging from 10 nanometers to 10 microns. This capability allows detailed analysis of aerosol particles, which is essential for understanding air quality and health effects associated with particulate matter. Though the costs can be prohibitive, the wealth of data it provides is invaluable.

Imagine owning a high-end camera that costs a lot but gives you incredible pictures. The SMPS is like that premium camera for air quality researchers—despite its high price, the detailed data it captures helps them analyze and understand particle distributions, just like the camera helps capture moments perfectly.

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