Air quality is the measure of the purity and healthiness of the air we breathe, determined by the levels of substances present, which include particulates and gaseous pollutants. In urban centres, air quality is shaped by high population density, traffic congestion, industrial activity, energy use, waste burning, construction and limited air circulation. It is assessed through a combination of ground-based monitoring stations, satellite observations and atmospheric modelling, which together help determine whether pollutant levels comply with national or international air quality standards. The World Health Organisation, WHO, Air Quality Guidelines serve as a global reference, providing recommended limits for major pollutants such as particulate matter (PM₂.₅ and PM₁₀), nitrogen dioxide, NO₂, Sulphur dioxide, SO₂, ozone, O₃, and carbon monoxide, CO. These guidelines identify pollutant concentrations associated with the lowest possible health risks. For example, WHO recommends that the annual mean concentration of PM₂.₅ should not exceed 5 µg/m³, while the 24-hour mean should not exceed 15 µg/m³. Although WHO guidelines are not legally binding, they act as a gold standard that countries can adopt or adapt based on local feasibility, pollution levels and regulatory capacity. In Kenya, the National Environment Management Authority, NEMA, is the primary body responsible for regulating and enforcing air quality standards. While NEMA has established guidelines and policies to manage key pollutants such as particulate matter, nitrogen dioxide, sulphur dioxide and ozone, publicly accessible and up-to-date details of Kenya’s specific pollutant limit values remain limited, particularly for fine particulates such as PM₂.₅.