Article by CAP team May 2023 ©

Most of us breathe automatically without giving it much thought.

When it comes to food and water, we can typically tell when they are safe to consume or when they are contaminated, but when it comes to the air we breathe, it is more difficult to assess the level of contamination.

The average adult takes about 20,000 breaths, breathing in about 11,000 litres of air per day. However, children playing, workers performing strenuous labour, and athletes may breathe double that volume of air per day, they also breathe more deeply, which pushes any pollutants suspended in the air further into their lungs.

With increasing levels of air pollution, perhaps it is time we looked more closely at how our health is affected by the air we breathe.

What is particulate matter

Understanding Particulate Matter

The air we inhale is primarily a mixture of nitrogen, oxygen, and argon. This air however also contains “particulate matter” or “PM” which is a complex mixture of solids and aerosols of various shapes, sizes, and chemical compositions. PM may also contain a variety of chemical elements such as organic compounds, inorganic ions, metallic compounds, elementary carbon, and other toxins.

Everyone is susceptible to the harmful consequences of inhaling PM. No one is immune! Young children, older adults, and those who have such as allergies, asthma, or more serious pre-existing medical conditions are especially vulnerable to these effects.

Some types of PM are more dangerous than others. Soot, smoke, and dust particles that are large or dark enough to be visible, we know how to avoid it. But it is the ultrafine particles that are the most dangerous. They are invisible to the human eye and small enough to enter deep into your lungs, circulation, and ultimately your organs.

What is particulate matter

These particles are defined by their diameter for air quality regulatory purposes as PM2.5 and PM10. Ultra-fine inhalable particles with a diameter less than or equal to 2.5 micrometres are referred to as PM2.5. They are too small to be seen by the human eye and are typically 50 to 70 times thinner than human hair. When inhaled, they can penetrate deeply into the human respiratory tract making them extremely harmful to human health.

An important distinction between dust and PM pollution is that the PM carries with it the by-products of the fuel burnt in its formation. Each speck of PM acts like a tiny suitcase full of charred residue from other chemicals released during the combustion of the fuel burnt. For example; PM released from motor vehicle engines contain residues of benzene and other hydrocarbons; Emissions from coal-fired power plants are likely to contain some mercury; Commercial agricultural biomass burning releases PM which have toxic chemical compounds from the pesticides and herbicides used; Whilst furnaces that burn plastic or other industrial waste release dioxins. When we breathe in these particulates, it is the toxic hitchhikers that are the most damaging to our health.

Health Impacts

How particulate matter affects human health is strongly correlated with its size. Particles with a diameter of 10μm or less generally pass through the nose and throat and reach the lungs. PM2.5 is so small, it can pass through the respiratory tract, attach to the surfaces of the deepest portions of the lungs, and enter your bloodstream and penetrate vital organs, including the brain where it causes lung inflammation and tissue damage.

Click on the picture to watch a short video explaining PM2.5

If inhaled for short periods of up to 24 hours, PM2.5 can cause irritation of the eyes, nose, throat, and upper respiratory tract, coughing, sneezing, and shortness of breath. It can also aggravate pre-existing respiratory conditions such as asthma, acute and chronic bronchitis, and other respiratory symptoms. As air pollution levels drop, the irritation typically disappears.

Short-term exposure can also cause and aggravate lower respiratory tract disorders and chronic conditions such as allergies, asthma, chronic obstructive pulmonary disease, and bronchitis. People with pre-existing medical conditions, such as heart disease, are at higher risk of arrhythmias, heart attacks, and even premature death from repeated short-term exposure to PM2.5.

Most of the PM10 that is inhaled is deposited on the surface of the respiratory tract and in the upper area of the lungs, causing lung inflammation and tissue damage. Asthma and chronic obstructive lung disease (COPD) have both been shown to worsen after short-term exposure to PM10, necessitating hospitalisation.

Long-term exposure to PM2.5 and PM10 pollution, over the course of months or years, can cause permanent respiratory problems such as asthma, chronic bronchitis, and heart disease, and lead to decreased lung function in children. It can also lead to premature death, especially in people suffering from chronic lung or heart diseases. The most susceptible people are young children, older adults, and those who have pre-existing conditions. [2]

What is particulate matter

The short- and long-term effects of PM2.5[1]

Click on the picture to watch a short video showing the health effects of inhaling PM2.5

Environmental Impacts

Several scientific studies [3] have demonstrated that particulate matter impairs visibility and negatively impacts the climate, ecosystems, and materials.

PM2.5 lowers visibility by changing how light is absorbed and scattered in the environment, as can be seen on days with heavy smog. While some particulate matter components such as carbon black contribute to global warming, others such as nitrates and sulphates have a cooling effect.

PM has a negative impact on plant, soil, and water ecosystems. These fine airborne particles settle on vegetation, soil, and water, where they are subsequently absorbed by vegetation and impact the clarity and quality of the water. Metal and organic chemicals carried by airborne PM have the greatest adverse effects on plants where they are shown to impede growth and yield.


PM once released can stay in the air for a long time, days, or weeks, and can travel hundreds of kilometres.

PM emissions can be either primary PM, directly from a source, or secondary PM, through the chemical reactions of gases such as sulphur oxides (SOx), nitrogen oxides (NOx), or other organic compounds in the atmosphere.

Natural sources of particulate matter may include wind-blown dust from open land, pollen, spores, mould, dirt, soil erosion, and natural vegetation fires.

Sources caused by human activity include:

  • Burning fossil fuels such as coal, petrol, oil, diesel, or wood, including emissions from motor vehicle exhausts.
  • Emission from coal-fired electric power generation and from other heavy industrial processes.
  • Agricultural burning.
  • Burning of waste.
  • Manufacturing of steel and metals, particularly the smelting and processing.

Installing Monitors to Understand the Air Pollution Problem.

In KwaDukuza will live in an area of over 10,000 km2 devoid of government air pollution reference monitors.

There is a saying “You cannot manage what you cannot measure.” The installation of CAP’s Independent Network of monitors satisfies the requirement of measuring PM concentrations. Unfortunately, their deployment will not resolve the issue on its own. The monitoring of PM concentrations serves as an air pollution strategy. The data from the monitors will provide information to help us define the air pollution problem and insights into how to solve it. The monitors will also allow us to track the progress of mitigation strategies by assessing the effectiveness and efficiency of policy interventions and enable us to carry out long-term trend analysis.

Meteorological conditions, topography, and emission sources all play a role in how we experience air pollution. Due to these local and regionally specific factors, the distribution and extent of pollution is different everywhere. Therefore, it is imperative to define and address the pollution problem at regional and local levels if we are going to successfully reduce PM concentration levels.

Why PM2.5 Monitoring is Important

  • It is everywhere! Particulate matter is released into the atmosphere through fossil fuel combustion, burning of waste, preharvest agricultural burning, power plants, and vehicle exhaust.
  • PM5 is a complex mixture of solids and aerosols that have detrimental effects on human health.
  • Monitoring PM5 levels is an effective technique to both identify and avoid exposure to elevated levels of particulate matter.
  • Real-time monitoring of PM5 levels help us develop an action plan to achieve agreed standards, provide an accurate air quality index, and to deliver health advisories.

Current Legislation

  • The South African legislation states that annual average PM5 concentrations should not exceed 20 µg/m3, while 24-hour average exposures should not exceed 40 µg/m3 more than 4 days per year.
  • The WHO updated guidelines (2021) state that the annual average of PM5 concentrations should not exceed 5 µg/m3, while 24-hour average exposures should not exceed 15 µg/m3 more than 3 – 4 days per year.
  • South African standards are 8 times higher than the WHO standard.
  • We will monitor our air quality and hold the government accountable to the WHO’s suggested incremental milestones toward cleaner air:
  • 35 µg/m3 annual mean, and 75 µg/m3 24-hour mean by 2025.
  • 25 µg/m3 annual mean, and 50 µg/m3 24-hour mean by 2030.
  • 15 µg/m3 annual mean, and 37.5 µg/m3 24-hour mean by 2035.
  • 10 µg/m3 annual mean, and 25 µg/m3 24-hour mean by 2040.
  • 5 µg/m3 annual mean, and 15 µg/m3 24-hour mean by 2045.

[1] The Impact of Fine Particulate Matter PM2.5 on the Cardiovascular System: A Review of the Invisible Killer – Nov 2022 – Shaherin Basith et al.

[2] Air pollution – How it Affects our Health – European Environment Agency – Oct 2022 – See EEA

[3] Environmental and Health Impacts of Air Pollution: A Review – I Manisalidis et. al. – Feb 2020 – See Frontiers.

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