Air Pollution and Respiratory Problems

  “Although a number of physical activities (volcanoes, fire, etc.) may release different pollutants in the environment, anthropogenic activities are the major cause of environmental air pollution. Hazardous chemicals can escape to the environment by accident, but a number of air pollutants are released from industrial facilities and other activities and may cause adverse effects on human health and the environment. By definition, an air pollutant is any substance which may harm humans, animals, vegetation or material. As far as humans are concerned an air pollutant may cause or contribute to an increase in mortality or serious illness or may pose a present or potential hazard to human health. The determination of whether or not a substance poses a health risk to humans is based on clinical, epidemiological, and/or animal studies which demonstrate that exposure to a substance is associated with health effects. In the context of human health, ‘‘risk’’ is the probability that a noxious health effects may occur.” (1)

  Air pollution can greatly affect your health, especially your respiratory system. Different individuals respond differently to pollution levels, but there are some whose health can be impacted in a manner greater than others. The causes of air contamination vary: wildfires, automobiles, manufacturing plants and heaters propelled by heating fuels, all contribute to the rise of pollution levels. The following two aspects can help you determine whether the air you are breathing is contaminated:

• If the air quality is bad
• If the smog level is so high that the fog is discernible due to its sunny coloring

  “Particulate air pollution is a mixture of solid particles and liquid droplets that vary in size, composition, and origin. Because only very small particles can be inhaled into the lungs, U.S. national health standards for the quality of ambient air are based on the mass concentration of “inhalable particles”, defined to include particles with an aerodynamic diameter of less than 10µm. Fine-particulate air pollution includes particles with aerodynamic diameter equal to or below 2.5µm. Whereas larger particles are derived chiefly from soil and other crystal materials, fine particles are derived primarily from the combustion of fossil fuels in transportation, manufacturing, and power generation. Fine – particulate pollution typically contains a mixture of particles including soot, acid condensates, and sulfate and nitrate particles. Fine particles are thought to pose a particularly great risk to health because they are more likely to be toxic than larger particles and can be breathed more deeply into the lungs.” (2)

How Air Pollution Affects the Respiratory System?

  If you live in an environment with a considerable amount of pollution, its effects on your health can be detected through experiencing conditions such as dyspnea, while engaging in activities that require energy, inflammation of the upper or lower airways and breathing problems. The extent to which a person experiences these conditions, is determined by each individual’s overall resistance, and the amount of pollution their location is affected by.

  “The size of particle pollutants is directly associated with the onset and progression of the lungs and heart diseases. Particles of smaller size reach the lower respiratory tract and thus have greater potential for causing the lungs and heart diseases. Moreover, numerous scientific data have demonstrated that fine particle pollutants cause premature death in people with heart and/or lung disease including cardiac dysrhythmias, nonfatal heart attacks, aggravated asthma, and decreased lung functions. Depending on the level of exposure, particulate pollutants may cause mild to severe illnesses. Wheezing, cough, dry mouth, and limitation in activities due to breathing problems are the most prevalent clinical symptoms of respiratory disease resulted from air pollution. Long-term exposure to current ambient PM concentrations may lead to a marked reduction in life expectancy. The increase of cardiopulmonary and lung cancer mortality are the main reasons for the reduction in life expectancy. Reduced lung functions in children and adults leading to asthmatic bronchitis and chronic obstructive pulmonary disease (COPD) are also serious diseases which induce lower quality of life and reduced life expectancy.” (4)

  “A number of mechanisms have been proposed to explain the adverse health impact of PM. Effects of PM that have experimental support are inflammation, cytokine and chemokine release, production of white blood cells, oxygen free-radical production in the lungs, endotoxinmediated cellular and tissue responses, stimulation of irritant receptors, and covalent modification of key cellular enzymes. Best characterized in humans are the effects of PM on airway inflammation. In human and animal studies, inhalation of particles elicits proinflammatory effects, cytokine production, and enhancement of allergic responses in the upper and lower airways. PM exposure is likely linked to inflammation through the generation of reactive oxygen species and oxidative stress. Although there is still debate about which particle components are responsible for producing reactive oxygen species, there is accumulating evidence that pro-oxidative organic hydrocarbons, such as polycyclic aromatic hydrocarbons and quinones, and transition metals, such as copper, vanadium, chromium, nickel, cobalt, and iron, play a role. The particle provides a template for electron transfer to molecular oxygen in these reduction and oxidation (redox) cycling events. In addition, target cells, such as airway epithelial cells and macrophages, generate reactive oxygen species in response to particle uptake by biologically catalyzed redox reactions that occur in the cell membrane and mitochondria.” (5)

Not Only Respiratory Consequences

  “Several case–control studies based upon M.I. registries or epidemiological studies with clinical review have found associations between NO2 and fatal M.I. but not non-fatal M.I. Thus far, the finding of associations for fatal MI only was interpreted as an evidence that air pollution particularly affects the frail, or acts to aggravate a disease progression caused by other factors. On the other hand, it is also possible that the outcomes of ischemic heart diseases are misclassified and combined as composite outcomes, where fatal outcomes are captured more precisely. Although there is increasing evidence that air pollution is associated with markers of early atherosclerosis, it is possible that air pollution will affect the underlying biological processes that predispose to atherothrombosis (which leads to MI and stroke) compared to atherosclerosis. Another explanation is that the type of outcomes affected by pollution are those that have higher case-fatality rates (e.g., arrhythmic sudden death has higher case-fatality rate than overall MI).” (7)

  “Two studies have reported significant associations between particulate matter air pollution and dysrhythmia, heart failure and cardiac arrest combined. These results are based upon smaller numbers of events, and require large cohort studies for further verification. The results are consistent with several studies documenting significant associations between short-term PM or NO2 exposure and mortality due to heart failure and dysrhythmia and defibrillator discharges.” (8)

  “Another hypothesized general pathophysiological pathway involves pulmonary and systemic oxidative stress, inflammation, atherosclerosis, and related cardiovascular disease. Over the last few decades, research has linked inflammation along with blood lipid levels to initiation and progression of atherosclerosis. This hypothesis proposes that low-to-moderate-grade inflammation induced by long-term chronic PM exposure may initiate and accelerate atherosclerosis. Short-term elevated PM exposures and related inflammation may also contribute to acute thrombotic complications of atherosclerosis increasing the risk of making atherosclerotic plaques more vulnerable to rupture, clotting, and precipitating acute cardiovascular or cerebrovascular events (MI or ischemic stroke). This hypothesis is not independent of the previous COPD hypothesis, because, as noted above, systemic inflammation associated with COPD may contribute to cardiovascular risk.” (9)

  “Biological effects of PM have been observed, and various general mechanistic pathways are proposed, including: (1) long-term exposure results in more rapid progression of COPD, and acute exposure exacerbates existing pulmonary disease; (2) pulmonary and systemic oxidative stress, inflammation, atherosclerosis, and related cardiovascular disease; (3) adverse changes in cardiac autonomic function; (4) vasculature alterations, including vascular tone and endothelial function; (5) systemic translocation of PM and prothrombotic effects; (6) modulated host defenses and immunity; and (7) PM-induced lung damage, declines in lung function, respiratory distress, and hypoxemia. None of these pathways have been adequately or fully explored.” (10)

  “Outdoor PM air pollution is estimated to be responsible for about 3% of adult cardiopulmonary disease mortality; about 5% of trachea, bronchus, and lung cancer mortality; and about 1% of mortality in children from acute respiratory infection in urban areas worldwide. This amounts to about 0.80 million (1.2%) premature deaths and 6.4 million (0.5%) lost life years.” (11)

  The constant and high exposure to contaminated air may cause an individual to suffer from serious health issues, including bronchopulmonary dysplasia, heart diseases, and bronchogenic carcinoma. Besides increasing the probability of causing long-term conditions, it can also aggravate the way of living of those dealing with problems in their respiratory system. People suffering from respiratory conditions, such as asthmatic attacks and various COPDs, are more vulnerable to polluted air. In extreme circumstances, gases and harmful substances in the air can even result in hospital admission for treatment and in certain cases, early death. General recommendations include the following:

  If you are aware that the air quality is worrisome, you should avoid too much physical exertion in the open air.

 If you are experiencing difficulties or discomfort while inhaling and exhaling, or pain in the chest, you should make sure to make an appointment with your physician.

  If you are being treated for diseases caused by air pollution, make sure to adhere to your treatment accordingly.

References:

(1) Human health effects of air pollution. Kampa, M. & Castanas, E. Elsevier. 2008. https://pdfs.semanticscholar.org/30d7/b5c1f9dee2b3b44c0f8359eb784051db74ba.pdf

(2) An Association between Air Pollution and Mortality in Six U.S. Cities. Dockery, D. W., Pope, C. A., Xu, X., Spengler, J. D., Ware, J. H., Fay, M. E., Ferris, B. & Speizer, F. E. The New England Journal of Medicine. 1993. (p.1) https://www.nejm.org/doi/full/10.1056/NEJM199312093292401

(3, 9, 10) Health Effects of Fine Particulate Air Pollution: Lines that Connect. Pope III, C.A. & Dockery, D.W. Journal of the Air & Waste Management Association. 2006. (p. 727, 729, 731, 732) http://toxicology.usu.edu/endnote/PM-HealthEffects-Pope2006.pdf

(4, 6) Effects of air pollution on human health and practical measures for prevention in Iran. Adel Ghorani-Azam, A., Riahi-Zanjani, B. & Balali-Mood, M. Journal of Research in Medical Sciences. 2016. http://www.jmsjournal.net/article.asp?issn=1735-1995;year=2016;volume=21;issue=1;spage=65;epage=65;aulast=Ghorani-Azam

(5) Atmosphere: Air Pollution–Related Illness: Effects of Particles. Nel, A. SCIENCE Vol. 308. 2005. (p.805) http://science.sciencemag.org/content/308/5723/804

(7, 8) Long-term air pollution exposure and cardio- respiratory mortality: a review. Hoek, G., Krishnan, R.M., Beelen, R., Peters, A., Ostro, B., Brunekreef, B. & Kaufman, J.D. Environmental health. 2013. https://ehjournal.biomedcentral.com/articles/10.1186/1476-069X-12-43

(11, 12) The Global Burden of Disease Due to Outdoor Air Pollution. Cohen, A. J., Ross Anderson, H., Ostro, B., Pandey, K. D., Krzyzanowski, M., Künzli, N., Gutschmidt, C., Pope, A., Romieu, I., Samet, J.M. & Smith, K. Journal of Toxicology and Environmental Health, Part A: Current Issues. 2005. https://www.researchgate.net/publication/7719358_The_Global_Burden_of_Disease_Due_to_Outdoor_Air_Pollution