Particulate matter is commonly categorized by size. In this context, PM₁₀ refers to particles with a diameter of up to 10 micrometres, which are large enough to be partially filtered by the upper respiratory system but can still impact air quality and health.
It is part of a broader group known as particulate matter (PM), which consists of a mixture of solid particles and liquid droplets suspended in the air. These particles can contain a wide range of chemical compounds and are either directly emitted or formed in the atmosphere through complex reactions involving pollutants from sources such as power plants, industries, and vehicles.
PM₁₀ particles are typically generated by mechanical processes such as road dust resuspension, construction activities, agriculture, and natural sources like pollen, ash, or desert dust. In outdoor environments, they are often associated with visible dust and local pollution sources. Indoors, these particles can enter from outside or originate from activities such as cleaning, cooking, or movement that disturbs settled dust.
Some PM₁₀ particles are visible to the naked eye (e.g. dust or pollen), while others are small enough to remain suspended in the air and only visible under a microscope. Due to their size, PM₁₀ particles are generally filtered by the upper respiratory system; however, they can still be inhaled and enter the airways.
Exposure to elevated levels of PM₁₀ can irritate the respiratory system and negatively affect air quality. It may worsen existing conditions such as asthma or bronchitis and, in more severe cases, lead to aggravated symptoms or hospitalization.
According to the World Health Organization (WHO), recommended exposure limits for PM₁₀ are:
- Short-term (24-hour average): below 45 µg/m³
- Long-term (annual average): below 15 µg/m³
Maintaining PM₁₀ levels within these limits is important, as both short-term spikes and long-term exposure to elevated concentrations can pose health risks.