Ambient Air Particulate Matter Levels in Selected Urban Centres of Niger Delta Region, Nigeria

This study measured total suspended particulate (TSP) matter load, particulate matter with aerodynamic diameter ten micrometer or less (PM 10 ) and two and half micrometer or less (PM 2.5 ) in five urban centres in the Niger Delta region, Nigeria in the dry and wet seasons from December, 2008 to September, 2009 using photometric laser-based particle counter instrument. The results showed that the seasonal mean varied in the range of 72.25±12.32- 320.06±235.42 µg m -3 for the TSP in the dry season and 16.31±4.77 – 87.94±27.32 µg m -3 for the wet season. The seasonal mean of (PM 10 ) ranged from 42.44±9.74 - 181.38±50.64 and 6.94±2.05 – 59.88±20.89 µg m -3 for the dry and wet seasons respectively. Similarly, PM 2.5 gave 13.56±2.63-55.00±29.45 µg m -3 and 1.81±1.11-12.88±3.48 µg m -3 respectively for the dry and wet seasons. The annual mean of TSP in all the cities were within World Health Organization (WHO) annual guideline limit of 230-250 µg m -3 . Also PM 10 annual levels exceeded the 20 µg m -3 WHO annual guideline limit while PM 2.5 annual levels in two cities (Uyo and PortHarcourt) exceeded the US annual National Ambient Air Quality Standard (NAAQS) of 15 µg m -3 . The F-test statistics revealed statistical significant difference in the dry and wet seasonal means of TSP in Eket and Uyo (p<0.05). The PM 10 dry seasonal level in Eket and Uyo wet seasonal level were significant (p<0.05) while PM 2.5 dry seasonal level in Eket and wet seasonal levels in Uyo and PortHarcourt were statistical significant (p<0.05). The study concluded that the high levels of PM 10 and PM 2.5 in all the cities monitored especially in the dry season may present a potential public health risk.