Climate change

Air Pollution – Does it affect our lungs?

Well, of course, it affects us but how? I will be doing 2 posts on air pollution, how it affects mammals and another on how it affects plants. One of the main reasons our air is harming our lungs is because of global dimming.

Global dimming

Global dimming is when there are so many solid particles in the air that affects the visibility of the air. The solid particles come from some aerosols (I will make a whole other post discussing the impact of aerosols), combusting (burning) fossil fuels, dust and volcanic eruptions. As you can imagine inhaling solid particulates is not the most beneficial thing for our lungs. So how do solid particulates affect the lungs? As solid particulates are so small (on average 1o micro-meters) we can not choke on them so they can pass through our alveoli (alveoli are”sacks” that carry out gas exchange and are one cell thick) and sometimes even into our bloodstream which can cause some slight problems.

diagram to show an aveolus and demonstarte how gas A and as B exchange across the surface

The diagram to the right shows an alveolus. Gas A would be oxygen and Gas B would be carbon dioxide. But, Gas A will not be 100% pure oxygen as the air around us is not 100% oxygen, it will be mostly nitrogen and (in this case, say we are near an active volcano or breathing in lots of car fumes) some solid particulates. As mentioned previously, solid particulates in particular carbon ones are very tiny, way smaller than an alveolus (200 micro-meters twenty times the size of a particulate), so may pass through the alveolar membrane (wall of alveolus), this does not always happen only the really small ones pass into the blood the larger ones we cough up. If they are in our blood it means the solid particles can get into our cardiovascular system which is our lungs and heart. This can cause several diseases like lung and heart disease, irregular heartbeat and aggravated asthma.

Why solid particulates affect our health?

They affect our health as they can trigger oxidative stress. Oxidative stress is when there is an imbalance between the number of free radicals (reactive atoms with a lone pair) and antioxidants in the body. This can cause inflammation in the lungs, heart and nervous system. Inflammation in those areas can cause distribution in their functioning ability.

Carbon Monoxide (CO)

Haemoglobin is a protein within red blood cells that attracts oxygen for transportation for aerobic respiration. Oxygen is attracted to the haemoglobin as it contains haems which are ferrous (Fe^+2). CO is also attracted to haems so competes with oxygen and eventually displaces oxygen. So oxygen can not travel around the body as efficiently. This can cause tiredness, nausea and even death at high levels.
CO is produced from car exhausts mainly. However, catalytic converters can reduce the volume of CO by adding oxygen.

2CO + O2 → CO2

So the exhaust will release CO2 which is much less harmful to us but maybe more harmful to the environment.

Nitrogen Dioxide

Pie graph showing the relationship bewtween where and how NOx emissions are produced

Nitrogen dioxide is an irritant gas which inflames airways and the lining of the lungs. This can cause complications in the lungs, like increased frequency of asthma attacks and bronchitis.

These problems occur because nitrogen dioxide is acidic and dissolves easily in water to form nitrous acid or nitric acid which causes the inflammation. In high levels, nitrogen dioxide will weaken the immune response to respiratory diseases. For more about the link with Nitrogen dioxide and the immune system read

Carbon dioxide

Many people are aware that carbon dioxide is a greenhouse gas (will go in more depth in next post) but many are not aware that carbon dioxide is an acidic gas. Why does it matter if carbon dioxide is acidic? Well yes, carbon dioxide is a waste product of gas exchange and we can just exhale the gas, but the levels of carbon dioxide are at extremely high levels. Levels in the atmosphere are around 400 ppm which means we also inhale carbon dioxide. High levels of carbon dioxide in the blood can change the pH of the blood to an acidic one.
Enzymes are proteins that carry out bodily functions (for example digestion) they require a specific pH to stay in their correct form. Changing the pH can alter the charge of amino acids breaking apart the structure of the enzyme meaning it can no longer work. This can cause symptoms like tiredness/ dizziness and an increased heart rate.

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