2. Ultra-fine Particulate Matter

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. The reason this is important is a lot of emission coming from vehicles, diesel analyzing particulate matter are in this size range.

Ultra-fine particulate matter (UFP) refers to particles that are extremely small, typically measuring between 300 nanometers and 500 nanometers. This size range is critical because many emissions produced by vehicles, especially diesel engines, fall within these dimensions. Understanding UFP is necessary to assess their impact on air quality and human health, as they can penetrate deep into the lungs and bloodstream.

Think of ultra-fine particulate matter like tiny dust particles in a sunny room. While larger dust particles are easy to see and catch, these ultra-fine particles are so small that they can go unnoticed and can easily be inhaled, much like how small pollen can enter our respiratory system without our awareness.

It is known very well known that then it is if you look at the particle size distribution we have seen that there is something called as a condensation and nucleation range which starts from the lower end and the higher end of particles are mainly from mechanical breaking, breakage, erosion that can also because they are originating from larger particles this is originating from vapor.

UFP is generated from various sources. On one hand, particles from combustion processes, like vehicles, begin as vapor at high temperatures and then condense into ultra-fine particles. On the other hand, mechanical processes such as demolition or construction can also produce smaller particles through erosion. Understanding this distinction helps in identifying pollution sources and implementing control measures.

Imagine boiling water to make steam. When the steam cools, it condenses back into tiny water droplets. Similarly, when gases from a car's exhaust cool, they can condense into ultra-fine particles that mix with the air we breathe.

Now the theory is further down we are going further down you are already in the nanometer nanoparticle range is few 100 nanoparticles, very difficult to measure. So how do you measure nanoparticle nanoparticles you cannot do gravimetry.

Measuring ultra-fine particulate matter poses significant challenges due to their size, often measured in nanometers. Traditional methods like gravimetry, which involves collecting particles and weighing them, are ineffective here because the mass of these tiny particles is too small to measure accurately. Instead, other sophisticated techniques are required to quantify and analyze these particles.

Measuring ultra-fine particles can be likened to trying to weigh a single hair strand. It's virtually impossible to get an accurate reading because the weight is so insignificant. Instead, scientists have devised more advanced methods to estimate their presence and size.

So people use what is called electrical mobility. And the instrument that is used to make is called as a differential mobility analyzer. And this instrument, what it does is it charges all the particles coming in. But depending on the size of the particles, different charges accumulate on particles.

One method used to analyze ultra-fine particles is through electrical mobility. A differential mobility analyzer charges incoming particles. The amount and nature of the charge depend on the particle size. This allows the instrument to separate particles based on their mobility influenced by their size and electrical charge. This method is effective in isolating specific particle sizes for further analysis.

Imagine a slide in a playground where children of different sizes go down. Those who are heavier (larger particles) might go faster while smaller children (smaller particles) might take longer. Similarly, in a differential mobility analyzer, particles are 'sorted' based on how they move in an electric field.

So, that method of measurement called as a condensation particle counter (CPC). These small nanoparticles you don’t have a way of counting it yet. So, but you will know how to count particles that are in the range of sub about 0.3 microns.

The Condensation Particle Counter (CPC) is another instrument used for measuring ultrafine particles. It works by allowing tiny particles to grow by condensation of vapor until they reach a detectable size. For example, particles smaller than 0.3 microns can be expanded, allowing them to be counted more accurately. This method enables better understanding of particle concentrations in the air.

Imagine trying to find tiny grains of sand on a beach. If you let them stick together and form bigger clumps, they become easier to see and count. In a similar way, the CPC allows small nanoparticles to grow, making it possible to measure and analyze them.

--