Published: 5th Oct, 2023
Context:
As per a study, recently published in the journal ‘Urban Climate’ on nanoparticles, has highlighted that vehicular emissions can potentially be transported from the respiratory system to other parts of the human body, creating more chronic and acute illnesses.
Highlights of the study:
- The study analysed nanoparticles from 10 to 1090 nanometers in diameter, over two periods — from April to June, and October to November in 2021 in Northwest Delhi.
- The study noted that nanoparticles in the road environment can penetrate deeper into the respiratory system than other pollutants.
- The study also stated that in urban environments, ultrafine particles of 1 to 100 nanometers can contribute up to 90% to the total particle number concentration.
- Researchers found that the size of these particles varies depending on sources.
- Source of Nanoparticles: In urban road environments, nanoparticles come mainly from the combustion process in automobiles, the study noted, adding that the concentration of these particles in urban roadside environments varies with human activity, particularly vehicular emissions.
- Factors responsible for dispersion of Nanoparticles:
- With rise in relative humidity, coagulation of these particles results in their concentration becoming high;
- High concentrations of these pollutants are found during peak morning and evening hours due to vehicular emissions; and
- Higher wind speed can result in dispersion of these particles.
- Significance of the study:
-
- The PNC (particle number concentration) estimates will be useful to determine deposition of particles in the human respiratory system based on various inhalation rates and associated physical activities.
- The quantitative outcomes of the present study can be used to estimate human health impacts, develop policies/standards, and initiate mitigation measures for pollution events with implications to climate change, and help move towards sustainability measures.
What are Nanoparticles?
- A nanoparticle is a small particle that ranges between 1 to 100 nanometers in size.
- Undetectable by the human eye, nanoparticles can exhibit significantly different physical and chemical properties to their larger material counterparts.
- The European Commission states defines that the particle size of at least half of the particles in the number size distribution must measure 100 nm or below.
- Most nanoparticles are made up of only a few hundred atoms.
Particle-Size distribution:
|
Particle Type |
Diameter Size Range |
|
0.1 nm |
|
1 to 100 nm |
|
100 to 2,500 nm
|
|
2500 to 10,000 nm |
|
100,000 nm |
Concerns associated to Nanoparticles:
- Natural Sources: Nanoparticles occur naturally in the environment in large volumes. For example, the sea emits an aerosol of salt that ends up floating around in the atmosphere in a range of sizes, from a few nanometres upward, and smoke from volcanoes and fires contains a huge variety of nanoparticles, many of which could be classified as dangerous to human health.
- Human-made (anthropogenic) sources: Man induced nanoparticles are emitted by large industrial processes, and in modern life it is particles from power stations and from jet aircraft and other vehicles (namely, those powered by internal-combustion engines; car tires are also a factor) that constitute the major fraction of nanoparticle emissions.
- Types of nanoparticles that are emitted include;
- Partially burned hydrocarbons (in soot),
- Ceria (cerium oxide; from vehicle exhaust catalysts),
- Metallic dust (from brake linings), calcium carbonate (in engine lubricating oils), and
- Silica (from car tires).
- Types of nanoparticles that are emitted include;
Can nanoparticles interact with living organisms?
- Nanoparticles can have the same dimensions as biological molecules such as proteins.
- In living systems, they may immediately adsorb onto their surface some of the large molecules they encounter as they enter the tissues and fluids of the body.
- This ability of nanoparticles to have molecules “sticking” to their surface depends on the surface characteristics of the particles and can be relevant for drug delivery uses.
- But the interaction with living systems is also affected by the dimensions of the nanoparticles.
- Key factors in the interaction with living structures include nanoparticle dose, the ability of nanoparticles to spread within the body, as well as their solubility. Some nanoparticles dissolve easily and their effects on living organisms are the same as the effects of the chemical they are made of.
- However, other nanoparticles do not degrade or dissolve readily. Instead, they may accumulate in biological systems and persist for a long time, which makes such nanoparticles of particular concern.
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