Particulates in the atmosphere are increasing. What can we do about it?

City covered in smoke
City covered in smoke

Atmospheric particulate matter (APM), also referred to as particulate matter or particulates, is the sum of all particles, liquids and solids suspended in the air. To refer to the mixture of particulates and air, the term aerosol is used. An example of these particulates includes gaseous contaminants, smoke, smog, dust, pollen, mould spores, viruses and bacteria.


A study performed by J. Karue, A.M. Kinyua and L. Njau in 1990-1991 in conjunction with University of Nairobi, the Centre for Nuclear Science Techniques, the Kenya Medical Research Institute and the Kenya Meteorological Department found a total of 9 elements that composed 20% of Nairobi's particulate matter. These 9 elements were: potassium, calcium, titanium, manganese, iron, zinc, bromine, zirconium and lead. Some other particulates found included the common cold virus and pollutant gases such as carbon monoxide, carbon dioxide, sulphur oxides and nitrogen oxides.

While much of urban air pollution is as a result of motor vehicle emissions, residential wood combustion is the major source of pollutants in the rural areas due to the use of wood energy is used for cooking. 

A review of published particulate monitoring studies carried out in Africa found that of all countries in Eastern Africa, Kenya had the highest level of particulate matter while Tanzania had the lowest. Between December 1993 and October 1994, the total suspended particulates were reported to be ranging between 30 to 80 micrograms per cubic metre of air. By 2003, the number of suspended particulate matter resulting from motorvehicle pollution was above 200 micrograms per cubic metre. Though air quality in the country is reported to be worsening, it is not routinely monitored. In fact, in some areas, it is not monitored at all.


1. Viruses and pathogenic bacteria cause diseases in human beings, plants and animals. Inhalation of dust, pollen and/or mould spores irritates the respiratory tract. Additionally, fine particulate matter (those that are about 2.5 microns or less in width—there are about 25,000 microns in an inch) can cause and exacerbate respiratory illnesses, including acute respiratory distress, asthma, chronic obstructive pulmonary disease, and lung cancer. According to the 2018 Economic Survey, respiratory illnesses are the leading cause of hospital visits in Kenya. 

2. Carbon monoxide, when inhaled, interferes with oxygen transport in the body leading to hypoxia (oxygen deficiency), resulting in death.

3. Many particulates are ozone-depleting substances (ODS). ODSs include carbon monoxide, nitrogen oxides, sulphur oxides, chlorofluorocarbons (CFCs), bromine, chlorine, halon, organohalogens and bromoflourocarbons. The ozone layer absorbs most of the sun's ultraviolet (UV) radiation. The more it's depleted, the more UV radiation the earth is exposed to. UV radiation, even in small quantities, is harmful when absorbed by living things because it causes mutations in the cells which result in abnormal growths, tumours and cancers. Furthermore, UV radiation can cause chemical particulates as well as free radicals in the atmosphere to react with each other causing an even more toxic atmosphere. Ozone depletion is also linked to global warming, and ODSs are also often greenhouse gases.

4. Acidic gases such as sulphur oxides and nitrous oxides are corrosive. When inhaled, they corrode the surfaces of the respiratory systems. They also burn holes through plants, and, in extreme cases, buildings. When it rains, the acidic gases dissolve in the rainwater causing a phenomenon known as acid rain.

5. Deposition of metallic elements in the lungs, as well as in other organs of the body, causes inflammation and metallic poisoning.

6. Aerosols in the air scatter light, causing fog and smog conditions. These reduce visibility and have been responsible for a number of accidents on the roads, airports, and harbours.

7. Fine particles of aerosols get inside the stomata of the leaves and interfere with the plant perspiration. Corrosive aerosols can scorch the leaves, while dust layers on the leaves reduce photosynthesis. Without photosynthesis and/or perspiration, plants will die, leading to the death of people and animals as well. 


There are several ways to reduce the amount of atmospheric particulates. These include:

1. Creating awareness of the situation. Being educated about the situation enables us to act appropriately, wisely and responsibly in order to come to eradicate the problem.

2. Using public transportation and carpooling to reduce the number of motor vehicles being used, and thereby reducing motor vehicle emissions. Governments should ensure that public transportation is efficient, affordable and accessible to all. Additionally, we should favour hybrid vehicles which have better fuel mileages as opposed to fuel guzzlers. Some countries charge higher taxes on fuel guzzlers and offer tax subsidies for hybrid cars as well as zero-emission vehicles. Walking and cycling should be encouraged, if and where possible. 

3. Reducing and totally doing away with products that contain ODSs. Despite the signing of the Montreal Protocol in 1987, there are still plenty of products in the market that contain ODSs. Before buying a product, make sure to check the list of ingredients. If it has ODSs, make a conscious effort not to buy it (unless it is necessary to) and go for the products without ODSs.

4. Introducing industrial laws against pollution. There are many ways for industries to purify their waste but most fail to do so because they want to maximize profits. Ultimately, industries have to realize that they cannot get away with pollution. The government (and other relevant organs) has to step up.

5. Creating and using air purification systems. There are innovative ways of incorporating purification systems into buildings. Read about them here.

1. Green Facts - Particulate matter

2. Air Pollution in Kenya: A Report by J. Karue, A.M. Kinyua and L. Njau.

3. Odhiambo GO, Kinyua AM, Gatebe CK, Awange J (2010) Motorvehicles air pollution in Nairobi, Kenya. Res J Environ Earth Sci 2(4):178–187

4. Elisaveta P. Petkova, Darby W. Jack, Nicole H. Volavka-Close & Patrick L. Kinney. (2013) Particulate Matter Pollution in African Cities.  Air Qual Atmos Health. 6, 603-614. DOI 10.1007/s11869-013-0199-6 

5. Fine Particulate Matter: The Culprit for Chronic Lung Diseases in China

5. 2018 Economic Survey Kenya

6. New Zealand Ministry for the Environment.

7. Wikipedia.