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human body. As discussed in Chap. 3, not all microorganisms are pathogenic
in nature.
Outdoor and ambient air pollution has been attributed as one of the major causes
of death (Ostro 2004; WHO 2015a, b, c). Health of children (WHO 2005), food, and
Fig. 4.24 People exposed to pollutants
Physical
•State of matter
(solid/liquid/gas)
• Size
• Shape
•Temperature
Chemical
•Reactivity
• Radioactivity
Biological
•Bacteria
•Virus
• Fungal Spores
•Pollen grains
Fig. 4.25 Examples of physical, chemical, and biological characteristics of pollutants, which
define their impacts on health
4 Introduction to Environmental Sciences