Particle pollution and health risks

October 28, 2026

5 minutes read

Particle pollution, also known as particulate matter (PM), is a general term for a mixture of solid particles and liquid droplets suspended in the air. It comes in many sizes and shapes and can contain a variety of components, including acids such as sulfuric acid; inorganic compounds such as ammonium sulfate, ammonium nitrate and sodium chloride; organic chemicals; soot; metals; soil or dust particles; and biological materials such as pollen and mould spores.

The air we breathe, both indoors and outdoors, contains particle pollution. Some particles, such as dust, dirt, soot and smoke, are large enough to be seen with the naked eye. Others are so small that they can only be detected using an electron microscope.

Coarse and fine particles

Particles of concern can be grouped into two main categories:

Coarse particles (PM10–2.5): These particles generally have diameters larger than 2.5 micrometres (µm) and less than or equal to 10 µm.

Fine particles (PM2.5): These particles generally have diameters of 2.5 µm or smaller. This group also encompasses ultrafine particles and nanoparticles, which generally have diameters of less than 0.1 µm. PM10 is a term that encompasses coarse and fine particle fractions, including ultrafine particles.

Primary and secondary particles

Some particles, known as primary particles, are emitted directly from sources such as construction sites, unpaved roads, smokestacks and fires. Other particles, known as secondary particles, form through complex atmospheric reactions involving chemicals such as sulphur dioxide and nitrogen oxides emitted by power plants, industries and automobiles.

Cooking, smoking, dusting and vacuuming can also produce particle pollution, particularly indoors. Particles produced by combustion are more likely to be fine particles, while those of crustal (earth) and biological origin are more likely to be coarse particles.

Particle pollution is found everywhere—not just in haze, smoke and dust, but also in air that appears clean. It can occur throughout the year and presents air-quality problems at concentrations found in many places. Some particles can remain in the atmosphere for days or weeks. Consequently, particle pollution generated in one area can travel hundreds or thousands of miles and affect air quality in regions far from the original source.

Particle pollution levels can be especially high near busy roads, in urban areas—particularly during rush hour—and in industrial areas. They can also rise when smoke from wood stoves, fireplaces, campfires or wildfires is present. Calm weather can allow air pollution to accumulate; hot, humid days with stagnant air can have much higher particle concentrations than days when rain helps remove pollutants from the atmosphere.

Because of their small size, fine particles outdoors can penetrate homes and other buildings. Therefore, high outdoor particle pollution levels can also increase indoor concentrations.

Source: United States Environmental Protection Agency (US EPA), website accessed September 25, 2026.

Mechanical and chemical processes

Particle pollution forms through two main processes: mechanical and chemical.

Mechanical processes break larger particles into smaller pieces while the material itself remains essentially the same. Dust storms, construction and demolition, mining operations and agriculture are among the activities that produce such particles. Wear of tyres, brake pads and other vehicle components can also generate particles.

Chemical processes in the atmosphere create many of the fine and ultrafine particles in the air. Pollutants such as elemental carbon (soot), volatile organic compounds, heavy metals and ammonia can be released through activities such as fuel combustion. Human activities and natural sources also emit gases that react with other gases in the atmosphere to form particles. For example, nitrogen dioxide and sulphur dioxide can undergo atmospheric reactions to form nitrate and sulphate particles.

Health effects of coarse and fine particles

The differences in particle size make a significant difference in how they affect human health. Our natural defences help us cough or sneeze out some coarse particles. However, these defences are less effective against smaller fine and ultrafine particles.

Fine particles can penetrate deep into the lungs, while some ultrafine particles and particle components may enter the bloodstream, contributing to effects beyond the respiratory system.

“Because of their small size, fine particles can penetrate deep into the lungs, while some ultrafine particles and particle components may cross into the circulation, contributing to effects beyond the respiratory system.”

Source: American Lung Association website, accessed September 25, 2026.

Evidence indicates that adverse health effects can occur even at relatively low concentrations of PM2.5, with risks generally increasing as exposure rises. A review of available evidence found that fine particle pollution is associated with increased risks of respiratory, cardiovascular, metabolic, autoimmune and neurological diseases, as well as cancers.

Source: Sangkham, S. (2024). “An update on adverse health effects from exposure to PM2.5.” Environmental Advances, 100121.

Vulnerable groups

People who live close to sources of emissions are among those most vulnerable to particle pollution. Other groups at increased risk include pregnant women, infants, children and adolescents, older adults above 65 years, people with lung diseases such as asthma and chronic obstructive pulmonary disease (COPD), people with cardiovascular disease, those living with obesity or diabetes, current and former smokers, people with lung cancer, people with low socioeconomic status, and people of colour.

Particle pollution includes PM10, which refers to inhalable particles generally 10 micrometres or smaller in diameter, and PM2.5, which refers to fine inhalable particles generally 2.5 micrometres or smaller.

For perspective, a particle measuring 10 µm in diameter is roughly five to seven times smaller than the diameter of a typical human hair, while a 2.5 µm particle is approximately 20 to 30 times smaller.

Although both PM10 and PM2.5 can enter the respiratory system, PM2.5 poses a greater health risk because of its ability to penetrate deeper into the lungs. Fine particles are also a major cause of reduced visibility and haze.

Air Quality Index

Air-quality alerts can help protect individuals and communities when particulate matter reaches harmful levels. Mobile applications can be used to check air quality daily. For example, AirNow provides the Air Quality Index (AQI), which indicates how clean or polluted outdoor air is and identifies associated health concerns.

The AQI translates air-quality measurements into numbers and colours to help people understand when they should take action to protect their health.

People living in polluted areas, including locations with heavy vehicle traffic, ongoing road construction and unpaved roads, should expect air quality to be affected and take appropriate precautions. Where exposure cannot be avoided, a properly fitted particulate respirator, such as an N95 or equivalent, may help reduce the inhalation of fine particles.

It is important to note that long-term exposure to fine particles in air pollution also increases the risk of developing chronic diseases such as hypertension, ischaemic heart disease, type 2 diabetes mellitus and certain cancers.

In Ghana, particle pollution is particularly relevant in rapidly growing urban areas, where heavy vehicular traffic, road construction, unpaved roads, open burning, industrial activities, generators and dust can contribute to poor air quality.

This means particle pollution is not a distant environmental problem; it is an everyday public-health concern.

Protecting ourselves from particle pollution

Individuals can take practical steps to reduce their exposure. These include avoiding tobacco smoking and second-hand smoke, improving indoor ventilation where appropriate, and avoiding heavily polluted areas whenever possible. When exposure cannot be avoided, a properly fitted particulate respirator, such as an N95 or equivalent, may help reduce the inhalation of fine particles.

Particle pollution may be invisible, but its effects on health can be significant. Cleaner air is therefore not merely an environmental issue; it is a public-health necessity.

Individuals can reduce their exposure, but lasting protection also requires cleaner transport, better control of industrial and construction emissions, reduced open burning and effective air-quality management.

The air we breathe matters to everyone.

BY DR. EDWARD AMPORFUL

The writer is a former Chief Pharmacist of Cocoa Clinic.

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