Investigating the effect of altitude and meteorological parameters on the concentration of particulate matter at an urban area of Kano State, Nigeria

Abstract

The impact of Particulate Matter (PM) on the health of individuals when its concentration is much in the atmosphere has been of concern and this has made it a topic of research to monitor its concentration in any given location. The aim of the study is to investigate the effect of altitude and selected meteorological parameters on concentration of Particulate Matter (PM) at an urban location in Kano State, Nigeria. The study was conducted at Dala Hill, which is in Dala L.G.A of kano state in northern Nigeria, at a height of 496, 519 and 530 meters above mean sea level (m.a.s.l) with measurements taken three times per day (morning, afternoon and evening) between November 2020 and February 2021. The PM concentration (PM_2.5 and PM₁₀) and selected meteorological parameters were measured using a handheld particulate matter monitor (PM monitor). The altitude range and barometric pressure were determined using a multifunction digital altimeter. During the study period, the maximum monthly average value of PM_2.5 and PM₁₀ at observation altitude of 496, 519 and 530 (m.a.s.l) are 85.6 and 110.2 μgm^-3, 67.7 and 85.2 μgm^-3 and 42.2 and 54.2 μgm^-3. By considering standard limit given by the Ambient Air Quality Standard (AAQS), it was observed that, the monthly average values of PM_2.5 concentration were above USEPA 24-hr Standard value while for PM₁₀ concentration were below USEPA 24-hr standard value. During the daily observation period, the study showed that, the over-standard limit of daily average value of PM_2.5 at the observation altitude of 496, 519 and 530 (m.a.s.l) were 96.7%, 81% and 41.3% for the overall period of the study area. While the highest number of daily average values of PM₁₀ concentration for the overall period study period were below standard limit except 13% at the observation altitude of 419 (m.a.s.l), 4.3% at 519 (m.a.s.l) and3.3% at 530 (m.a.s.l). These showed that, the PM_2.5 concentration was higher than that of PM₁₀ at the study area. A statistical analysis using Pearson Correlation Analysis showed that PM concentration (PM_2.5 and PM₁₀) has a negative correlation with temperature and relative humidity and positive correlation with barometric pressure. As temperature and relative humidity increases the PM concentration decrease, while as barometric pressure increases the PM concentration also increases. As a general finding, the experimental result showed that, the PM concentration decrease with increasing altitude.