The year is marked by changes in the weather, ecology, and amount of daylight, and these changes result from earth's orbit around the sun and earth's axial tilt relative to the ecliptic plane. In the temperate and subpolar region of the earth, there are four seasons in a year; spring, summer, autumn, and winter. In tropical and subtropical regions which Nigeria is one of them, there are two seasons; the rainy (wet or monsoon) season and the dry season (Harmattan); the Harmattan dust constitutes haze, largely from the anthropogenic source of the particulate matter.
It blows during the dry season, which occurs during the lowest-sun months, when the subtropical ridge from high pressure stays over the Central Sahara desert and when the low-pressure inter-tropical convergence zone stays over the Gulf of Guinea. It is characterized by dry and dusty northeast trade wind that blows from the Sahara desert into the Gulf of Guinea between the end of November and the middle of March. On its passage over the Sahara, it picks up fine particles (between 0.5 and 10 micromaterials).
The depletion ability of Harmattan dust also reduces visibility drastically during the Harmattan season. This depletion characteristic has a multiplier effect. It affects agricultural yield and brings about poor visibility that affects transportation, especially the aviation industry. Travelers express their displeasure over the arrival of the Harmattan season as it brings discomfort to people. Harmattan also affects the economic status of people, as a lot of people have to buy new clothes and sweaters that will enable them to manage the cold and dusty weather condition.
This research is expected to examine the impact of the changes in human health and comfort attributable to extreme weather and climatic conditions by Harmattan. The high rate of dust concentration has adversely contributed to the condition of human health and the population.
The effect of dust and sand stirred by the wind which known as Harmattan haze has cost airlines in millions because cancelation and diverted flights every year. This dry dust (Harmattan wind), northeast wind occurs in West African north of the Equator. Its effect extends from just north of the Equator in January, almost to the Northern Tropic in July. The Harmattan wind stream occasionally extends south of the Equator during the northern winter as an upper air wind over southwesterly monsoon. The atmospheric haze prevails early morning and occasionally toward the evening; there is an incursion of fog in Northern Lokoja.
The Harmattan dust particles affect negatively the health of the people causing the respiratory disease to adults and children. Health cases such as cough, catarrh, and respiratory disease are mostly reported in the hospitals during the Harmattan season. The skin is usually dry with accompanying dry cracking of the lips. The results obtained from the spectral radiation in most areas of Southwestern Nigeria show that December has more turbidity coefficient. The Harmattan season is categorized into periods with moderate characteristics called the background Harmattan.
A Guest Editorial