Review A review on the human health impact of airborne particulate matter Ki-Hyun Kim a, ⁎, Ehsanul Kabir b , Shamin Kabir c a Department of Civil and Environmental Engineering, Hanyang University, Seoul 133-791, Republic of Korea b Department of Farm, Power & Machinery, Bangladesh Agricultural University, Mymensingh, Bangladesh c LMC Clinic, Mymensingh, Bangladesh abstract article info Article history: Received 21 July 2014 Accepted 7 October 2014 Available online xxxx Keywords: Particulate matter PM 10 PM 2.5 Human health Particle size Particulate matter (PM) is a key indicator of air pollution brought into the air by a variety of natural and human activities. As it can be suspended over long time and travel over long distances in the atmosphere, it can cause a wide range of diseases that lead to a significant reduction of human life. The size of particles has been directly linked to their potential for causing health problems. Small particles of concern include “inhalable coarse parti- cles” with a diameter of 2.5 to 10 μm and “fine particles” smaller than 2.5 μm in diameter. As the source–effect relationship of PM remains unclear, it is not easy to define such effects from individual sources such as long- range transport of pollution. Because of the potent role of PM and its associated pollutants, detailed knowledge of their human health impacts is of primary importance. This paper summarizes the basic evidence on the health effects of particulate matter. An in-depth analysis is provided to address the implications for policy-makers so that more stringent strategies can be implemented to reduce air pollution and its health effects. © 2014 Elsevier Ltd. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 2. Classification and source of PM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 3. Effect of particle size and particle components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 4. Human diseases associated with PM pollution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 5. Mortality of PM pollution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 6. Pollution scenario and regulation guidelines for PM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 7. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 1. Introduction Air pollution is a process that introduces diverse pollutants into the atmosphere that cause harm to humans, other living organisms, and the natural environment (Kinney, 2008; Brauer et al., 2012; Kim et al., 2013). The health effects of air pollution, observed from both indoor and outdoor environments, have been of great concern due to the high exposure risk even at relatively low concentrations of air pollut- ants. More than two million deaths are estimated to occur globally each year as a direct consequence of air pollution through damage to the lungs and the respiratory system (Shah et al., 2013). Among these deaths, around 2.1 and 0.47 million are caused by fine particulate matter (PM) and ozone, respectively (Chuang et al., 2011; Shah et al., 2013). The presence of PM poses more danger to human health than that of ground-level ozone and/or other common air pollutants (like carbon monoxide). Airborne PM consists of a heterogeneous mixture of solid and liquid particles suspended in air that varies continuously in size and chemical composition in space and time (WHO, 2013). It is found that the chemical constituents of PM are diverse enough to include nitrates; sulfates; elemental and organic carbon; organic compounds (e.g., polycyclic aromatic hydrocarbons); biological compounds (e.g., endotoxin, cell fragments); and metals (e.g., iron, copper, nickel, zinc, and vanadium) (WHO, 2013). Numerous scientific studies have explained particle exposure as the source of various health problems including premature death in people Environment International 74 (2015) 136–143 ⁎ Corresponding author. Tel.: +82 2 2220 2325. E-mail addresses: kkim61@hanyang.ac.kr, kkim61@nate.com (K.-H. Kim). http://dx.doi.org/10.1016/j.envint.2014.10.005 0160-4120/© 2014 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Environment International journal homepage: www.elsevier.com/locate/envint