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Special Feature: What are Ultrafine Particles?

Particulate matter (PM) is the principal component of air, of which ultrafine particles (UFP) are those with a diameter of 100 nm or less. There is a growing concern in the public health community about the contribution of the UFP to human health. The potential for UFP to cause harm to health is great. However, its source, mechanism, and precise role in many illnesses are still largely unknown. The special issue provides comprehensive reviews of the UFP and related effects on human health and disorders, which is an invaluable resource for understanding the current status and future perspectives of UFP management.

Editorial

Review

Tiny particles found in air pollution enter the body usually through the lungs and disperse to other organs, causing more inflammation and cellular toxicity than larger particles. Dean Schraufnagel from the University of Illinois at Chicago, USA, reviews the way by which nano-sized air pollutants threaten human health. He describes how ultrafine particles measuring less than 100 nanometres in diameter elicit greater inflammatory responses and stay in the lungs longer than larger particles. Repeated contact with extremely small particulate matter can trigger heart disease, diabetes, cancer, neurological disorders and respiratory ailments, especially among children and people with long-term occupational exposure. Much remains to be learned about the disease-causing properties of these nanoparticles and their long-term effects. Further developments in understanding remain handicapped by the lack of international standards and reporting measures.

Review Article | Open Access | | Experimental & Molecular Medicine

Ultrafine particles (UFPs) from auto exhaust, factory emissions, and woodburning negatively affect human health and can alter weather patterns. UFPs, particles less than 100 nanometers, smaller than the smallest bacterium, are the most common airborne particles. Their size allows them to penetrate the deepest lung passageways, sometimes carrying toxic metals or organic compounds that trigger inflammation and disease. Hyouk-Soo Kwon at the University of Ulsan, Seoul, South Korea, and coworkers have reviewed the sources and effects of UFPs. Auto engines are a primary source; recent improvements in combustion technology have resulted in production of smaller particles, with worse effects on health. UFPs have also been found to affect cloud formation and behavior, altering rainfall patterns and potentially causing flooding or drought. Understanding the properties of UFPs will help find ways to mitigate their effects.

Review Article | Open Access | | Experimental & Molecular Medicine

The ultrafine particles (UFPs) in air pollution aggravate respiratory illnesses via oxidative stress and inflammation, according to a review by South Korean and US researchers. Defined as particles less than 100 nm in diameter, UFPs are about 1/1000th the thickness of a human hair. Inhaling UFPs is known to aggravate respiratory illnesses such as asthma, but the mechanisms remain poorly understood. An-Soo Jang at Soonchunhyang University Bucheon Hospital, Korea and co-workers have reviewed the evidence on how UFPs harm the airways. They report that UFPs are readily deposited in the lungs, where they trigger production of reactive oxygen species, highly reactive molecules that cause cellular and DNA damage. UFPs also provoke airway inflammation, and long-term exposure can scar the lungs. These results will aid in protecting at-risk individuals from the harmful effects of air pollution.

Review Article | Open Access | | Experimental & Molecular Medicine

Tiny bacterial particles found in ultrafine airborne dust in homes and workplaces can trigger inflammation in the airways and increase the risk of developing chronic lung disease. Yoon-Keun Kim at MD Healthcare Inc in Seoul, South Korea, and co-workers review current understanding of the impact of ultrafine particles on disease development. Persistent, long-term exposure to molecules and extracellular vesicles from bacteria can trigger excess proinflammatory protein production in the body. Over time, this exacerbates immune dysfunction and increases the chances of developing conditions such as asthma, chronic obstructive pulmonary disease and lung cancer. Breathing in lipopolysaccharides shed from the membranes of certain bacteria may pose the greatest risk of developing chronic lung disease. The researchers call for urgent research to find ways of limiting lipopolysaccharides in indoor environments and optimizing air quality.

Review Article | Open Access | | Experimental & Molecular Medicine