„An unrecognized hazard can never be controlled„WHO, 1999. Hazard Prevention and Control in the Work Environment: Airborne Dust.
We all want to live long, healthy lives. We are always on the alert for possible risks, instinctively. We prick up our ears and look both ways before crossing the street. We taste the curry tentatively to make sure it’s not too spicy, and sniff at the waft of air from the oven, to ensure nothing is burning. And we dip a toe in the bath-water, just in case it’s too hot. In avoiding those things which might harm us, we employ our five senses: sight, hearing, taste, smell and touch. They form our early-warning system which wards us from danger.
There are dangers out there, though, that our early-warning system cannot detect. As science has progressed, we have become more and more aware of the existence of entities which go by our senses unobserved: gravity, the subconscious, bacteria, and so on. The senses cannot help in assessing the risk such unobservable entities pose. Instead, the intellect must take charge; the only way to adopt protective measures against any threats such entities may pose is to become well-informed as to the potential threats themselves.
This is the purpose of this article. One of the most common unobservable threats we encounter through our daily lives is air pollution, and, particularly, dust. Here we will detail how dust harms your body, so as to allow a proper consideration of the suitable precautions one can take.
How does dust harm the body: descriptive framework
There are numerous factors which affect how exposure to dust pollution can harm your body. The amount of time you are exposed, the amount of dust you are exposed to, and the fineness of the dust all play a role. This can make describing exactly how dust harms your body a difficult task; it can do so in a litany of ways, and can result in short-term and long-term health effects.
Additionally, the ways in which we quantify the harm the dust causes are also innumerate. We can talk of the harm the dust directly causes, by virtue of it lodging itself in your body, or of the harm it indirectly causes, through a greater susceptibility to other health problems caused by its general weakening of the body. We will in this article confine our discussion to the direct harm dust pollution can inflict upon your body, while remembering that this is just a small part of the true damage caused.
Where the difficulties faced in an accurate description of dust’s full range of health effects prove complex, the means by which it harms your body is simple: it forms, in some way, a physical impediment to your body’s proper functioning. This is the case for both short-term and long-term damage.
How does dust harm the body: short-term exposure
We’ll describe the short-term effects first. Imagine you’re walking past a construction site, and engulfed in a cloud of work dust blown up by the wind. In this you’re exposed to an intense concentration of dust, made up of both fine and coarse dust particles, but just for a short period of time. You will start to cough and wheeze, your eyes will start to water and become irritated, and you will have difficulty breathing properly. This is not the actual harm the dust is effecting upon your body, however. These are simply your body’s defences reacting to the dust’s attack (See here for how the body defends against dust pollution).
The dust’s danger is, as said prior, simple: it poses a physical obstacle to the workings of your body. In the eyes, the dust gathers under the eyelids, inhibiting sight, and cuts at your eyes, forcing them to close. In the mouth and throat, the dust lines and blocks the air passageways, inhibiting the proper intake of oxygen and scratching their interior. In the nose, the dust again blocks the airways, and removes your power of smell. These are all short-term effects of the dust, and are just the most obvious and immediate – exposure in the short term to extremely high concentrations of dust can still lead to the development of dangerous conditions, like acute silicosis.
In any case, while the aforementioned symptoms may seem minor, they can exacerbate pre-existing conditions in the cardiovascular and respiratory systems and put the body under extra strain. This is why studies have found that even a short exposure to dangerous levels of dust can lead to an increased hospitalisation rate, with each 1μg/m3 extra resulting in 2050 more admissions, where another study found a correlation between an increase in the mortality rate and higher PM10 rates in just the three days prior to death.
How dust does harm the body: long-term exposure
The long-term effects are different, however. Imagine that every time you went outside, or you opened a window, you were exposed to air that contained constantly high levels of particulate matter which was not yet visible. This is a common reality in modern cities. While you might not experience the short-term effects mentioned above, the dust is imperceptibly causing long-term harm.
“The effects of long-term exposure are much greater than those observed for short-term exposure, suggesting that effects are not just due to exacerbations, but may be also due to progression of underlying diseases.“(page 11, REVIHAAP).
The long-term inhalation of dust particles not only exacerbates the negative effects felt when only inhaled in the short-term, but also its constant presence in the respiratory system can lead to the development of health problems unique to long-term exposure. These tend to be far more problematic and deadly than those felt with only short-term exposure.
Yet the harm is once again rather simple: the dust, in some way, forms a physical impediment to the proper functioning of your body’s systems. The harm is only this time more sinister, as the longer time of exposure allows the dust to enter deeper and deeper with greater regularity, and forces your body to adapt to it in ways which causes different types of health complications.
So, for instance, the longer amount of time exposed to fine particles heightens the likelihood that they will evade your body’s defences and reach your lungs. Here, they will be engaged by the autoimmune system. This engagement of the immune system weakens your protection against other threats, as the system is already occupied. We can see this playing out in the Coronavirus’ heightened mortality rate in regions with high ambient levels of dust pollution. The inhabitants of such regions have had constantly engaged autoimmune responses to the particulate matter they have regularly been inhaling. The onset of the Covid-19 outbreak simply put more pressure on already hard-working immune systems, and some, tragically, could not cope.
This is sadly just one of the effects of long-term exposure to PM pollution. It also hugely heightens the likelihood of developing chronic respiratory illnesses. This can be seen through noting the surprising variety of chronic respiratory condition, each associated with a particular profession. So, for instance, bird breeders contract bird fancier’s lung, farmers farmer’s lung, and cheese workers cheese worker’s lung. As each profession demands long-term exposure to a certain type of airborne dust, each profession leads to a slightly different chronic respiratory condition. Breathing in dust over a long period of time leads to these chronic conditions: the continued and constant presence of a certain type of dust particle causes its own specific type of problem.
Giving an overview to the effects of long-term exposure can therefore be difficult: while the amount of suffering each type of dust particle causes may be comparable, the exact outcomes it may have can differ. But, to speak generally, we can simply state that long-term exposure to dust pollution reduces your quality of life. There are various studies which have chronicled the long-term results of poor air quality. The WHO report that in Europe at least a year is shaved off of continent-wide life expectancy values due to exposure to particulate matter, „mostly due to increased risk of cardiovascular and respiratory diseases, and lung cancer“ .
In 2009 a study looked at air pollution data from over 200 US counties for two 5-year periods, the first from 1978 to 1982, and the second from 1997 to 2001. Comparing the air quality of the two times alongside a comparison of their respective life expectancies showed that, on average, for each reduction of 10µg/m³ one could expect to live for a further half a year.
Dust harms our bodies in countless ways, many of which we are not even aware of yet. Research into just how the physical presence of dust particles affects our inner workings is still only at its inception, and much more work is needed to work out how different types of dust particles with different chemical compositions differ in the harm they cause the body, and what it is about their composition that causes this.
What is clear, however, is the need to reduce dust pollution levels, both in terms of limiting short-term exposure for workers and the public alike through targeted measures, and in terms of reducing long-term concentration levels as much as possible, so as to limit the subtle build up of pernicious health effects. One of the key elements in such a programme will be effective, efficient and environmentally friendly dust suppression.
Keet et al., (2017). Long-Term Coarse Particulate Matter Exposure is Associated with Asthma among Children in Medicaid. American Journal of Respiratory and Critical Care Medicine [online]. 197(6), 737-746. [Viewed 19.05.2020]. Available online: https://doi.org/10.1164/rccm.201706-1267OC
Pope et al., (2009). Fine-Particulate Air Pollution and Life Expectancy in the United States. The New England Journal of Medicine [online]. 360(4), 376-86. [Viewed online 19/05/2020). Available online: https://www.nejm.org/doi/10.1056
Wei et al., (2019). Short term exposure to fine particulate matter and hospital admission risks and costs in the Medicare population: time stratified, case crossover study [online]. BMJ. 367, 1-12. [Viewed online 19.05.2020]. Available from: http://dx.doi.org/10.1136/bmj.l6258
WHO, (1999). Hazard Prevention and Control in the Work Environment: Airborne Dust. WHO/SDE/OEH [online]. [Viewed 19.05.2020]. Available online: https://www.who.int/occupational_health/publications/airdust/en/
WHO Regional Office for Europe, (2013). Review of evidence on health aspects of air pollution – REVIHAAP Project: Technical Report [Internet]. Copenhagen: WHO Regional Office for Europe. Available from: https://www.ncbi.nlm.nih.gov/books/NBK361803/
Zeka et al., (2005). Short term effects of particulate matter on cause specific
mortality: effects of lags and modification by city characteristics [online]. Occupational Environmental Medicine. 62, 718-725. [Viewed online 19.05.2020]. Available from: https://doi.org/10.1136/oem.2004.017012