This article discusses the different ways in which pollution can affect human health, and their underlying mechanisms. A number of natural and anthropogenic processes release chemicals to the environment, some of which are hazardous to human health and habitat. These include gaseous pollutants:  carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen oxides (NO_x), volatile organic compounds (VOCs), ozone (O₃); heavy metals; and particulate matter (PM_2.5 and PM₁₀). Pollution has both acute and chronic health effects ranging from cell level to whole organ systems, and are linked with premature mortality and reduced life expectancy.

Respiratory system can be affected by all kinds of air pollution in high concentrations, but similar effects are visible at long-term exposure to low concentrations. They include:

• Nose and throat irritation, bronchoconstriction, dyspnoea
• Lung  inflammation, respiratory infections
• Reduced lung function, asthma, emphysema

Cardiovascular system affects many other organs, especially those requiring a lot of oxygen (i.e. brains). This has many side-effects:

• Reduced capacity to transfer oxygen may lead to impaired concentration, slow reflexes, confusion
• Changes in blood coagulation may lead to  angina or even myocardial infraction
• Inhibited haematopoiesis may lead to tachycardia, increased blood pressure, anaemia
• Ischemic heart disease

Nervous system is mainly affected by heavy metals and dioxins. Neurotoxic components may lead to i.e.:

• Memory disturbances, sleep disorders, fatigue
• Hand tremors, blurred vision, slurred speech
• Impaired mental development

Other effect include heavy metal caused kidney and liver damage, and perhaps the most importantly the developmental effects of pollutants on foetuses. The risks of spontaneous abortion, reduced fetal growth and malformations are increased. Impairments of motor and cognitive abilities as well as growth  could result from maternal exposure.

At the cellular level, pollutants often cause inflammatory responses and inhibit normal cell function and their signaling. The complex mechanisms of negative effects might lead to:

• Atherosclerosis, heart attacks, stroke
• Chronic inflammatory diseases (rheumatoid arthritis)
• Cataract
• Central nervous system disorders (Parkinson’s, and Alzheimer’s disease), age related disorders
• Cancer
• Hormonal dysfunction

The impacts depend on the pollutant type, its concentration, length of exposure, other coexisting pollutants and individual susceptibility. However, people living in cities  are exposed to a greater extent and occupational exposure of modern housing. The researchers conclude, that pollution is a major threat to human health and well-being, and measures to reduce our exposure should be put in action.