Evaluation of real-time monitored ozone concentration from Abuja, Nigeria.

Real-time ozone (O3) concentration is vital for accurate analysis of O3 to inform the public about O3 concentrations that may have an adverse effect on health. Few studies have analysed air pollution in Abuja, Nigeria and non on real-time ozone concentrations. As a result, there is a scarcity of data and information on real-time ozone pollution, pointing to a gap that needs to be urgently closed to enable a better understanding of ozone pollution and the causes and consequences in terms of the associated health risks.In this study, -time concentrations of ground-level ozone were measured in a busy urban pollution monitoring station. Using a real-time ozone monitor to enable real-time monitoring of O3 concentration of ozone for the first time in Abuja. The ozone concentrations followed a clear pattern with high concentrations being recorded during the dry (harmattan) season. Concentrations higher than the WHO standard of (eight-hour averaged) 100 µg/m3, occurred on 53 days over the 5-month dry season. Of those 53 days, 18 had ozone concentrations greater than 200 µg/m3. Daily patterns showed a rise throughout the day, reaching a peak in the evening. Weekday/weekend differences were less pronounced than those found in other studies. High temperatures and local climatic conditions in Abuja encourage the formation of ozone. In this study, we confirm the concentration of ozone, and the pattern can be episodic and potentially damaging to health. There is a need for better regulation and measures to reduce ozone, particularly when local climatic conditions, such as harmattan, favour the development of photochemical smog in such settings.

Association of Meteorological Factors With COVID-19 During Harmattan in Nigeria.

Harmattan is a season of dry, cold, dusty wind, and haze that is peculiar to West Africa. This season and COVID-19 share common conditions such as malaise and respiratory issues like as runny nose, cough and sneezing, and raise a question of a possible relationship that begs to be answered. This study investigated whether the meteorological factors of humidity and wind speed during harmattan have association with COVID-19 incidence and mortality in the 2 major COVID-19 epicenters of Lagos state and the Federal Capital Territory (FCT) in southern and northern geopolitical regions of Nigeria respectively. Data used were from March, 2020 to February, 2022, which corresponded to the period of 2 years after the first case of COVID-19 was detected in Nigeria. Correlation analysis was performed using incidence or mortality data on COVID-19 over the duration of 2 years and during the harmattan periods, as well as the humidity and wind speed data for the corresponding periods. Our results showed that there was no significant correlation between the humidity or wind speed and COVID-19 daily incidence or mortality during the harmattan and non-harmattan periods in Lagos state. In the FCT however, there was a significant positive correlation between humidity and COVID-19 incidence, as well as a negative correlation between wind speed and COVID-19 incidence. No significant correlation existed between humidity or wind speed and daily mortality. Taken together, the findings of this study show that weather components of the harmattan season have association with COVID-19 incidence but not mortality, and the association could vary depending on location.

Impact of Seasonal Changes on Asthma Control in North-Western Nigeria.

BACKGROUND: Asthma control is poor worldwide and is often affected by changes in environmental conditions. Effort to determine the cause of this heavy burden on patients and the healthcare system is crucial. AIM: To determine the role of seasonal changes on asthma control in Sokoto, North-Western Nigeria. METHODS: One hundred and one (101) patients with physician diagnosed asthma were consecutively recruited after obtaining informed consent. A structured researcher administered questionnaire was used as instrument of data collection and asthma control test questionnaire was also used to assess level of asthma control in each participant. Five items with a 4-week recall were assessed. Data for temperature, humidity, wind and rain was obtained from the Nigerian Meteorological Agency (NIMET), Sokoto. We computed frequency and level of asthma control with seasons of the year and weather variables. RESULTS: One hundred and one patients comprising 71 females and 30 males with a mean age of 32.14 ± 10.68 years participated in the study. Level of asthma control was found to be poor among the participants with 41(40.6%) having very poorly controlled asthma, 30(29.7%) with not well controlled and 30(24.8%) well controlled asthma respectively. Among patients with very poorly controlled asthma, 22(48.9%) occurred during harmattan season and 14(31.1%) during rainy season. Weather parameters such as humidity shows significant relationship with asthma control (B= -0.504, P= 0.031, 95% CI [-0.012, -0.0253]). CONCLUSION: The study shows that asthma control is poor among the participants and presentation with poor asthma control is more during harmattan season.

CONTEXTE: Le contrôle de l'asthme est médiocre dans le monde entier et est souvent affecté par les changements des conditions environnementales. L'effort pour déterminer la cause de ce lourd fardeau pour les patients et le système de santé est crucial. OBJECTIF: Déterminer le rôle des changements saisonniers sur le contrôle de l'asthme à Sokoto, dans le nord-ouest du Nigeria. MÉTHODES: Cent un (101) patients atteints d'asthme diagnostiqué par un médecin ont été recrutés de manière consécutive après avoir obtenu leur consentement éclairé. Un questionnaire structuré administré par le chercheur a été utilisé comme instrument de collecte de données et le questionnaire de test de contrôle de l'asthme a également été utilisé pour évaluer le niveau de contrôle de l'asthme chez chaque participant. Cinq éléments avec une période de rappel de 4 semaines ont été évalués. Les données sur la température, l'humidité, le vent et la pluie ont été obtenues auprès de l'Agence météorologique nigériane (NIMET) de Sokoto. Nous avons calculé la fréquence et le niveau de contrôle de l'asthme en fonction des saisons de l'année et des variables météorologiques. RÉSULTATS: Cent un patients, comprenant 71 femmes et 30 hommes, avec un âge moyen de 32,14 ± 10,68 ans, ont participé à l'étude. Le niveau de contrôle de l'asthme s'est avéré médiocre parmi les participants, avec 41 (40,6 %) ayant un asthme très mal contrôlé, 30 (29,7 %) un asthme non bien contrôlé et 30 (24,8 %) un asthme bien contrôlé, respectivement. Parmi les patients souffrant d'asthme très mal contrôlé, 22 (48,9 %) ont été signalés pendant la saison de l'harmattan et 14 (31,1 %) pendant la saison des pluies. Les paramètres météorologiques tels que l'humidité montrent une relation significative avec le contrôle de l'asthme (B= -0,504, P=0,031, IC à 95 % [-0,012, -0,0253]). CONCLUSION: L'étude montre que le contrôle de l'asthme est médiocre parmi les participants et que les cas d'asthme mal contrôlé sont plus fréquents pendant la saison de l'harmattan. MOTS-CLÉS: Asthme, Contrôle de l'asthme, Saison, Harmattan.

Prediction of personal exposure to PM2.5 in mother-child pairs in rural Ghana.

BACKGROUND: Air pollution epidemiological studies usually rely on estimates of long-term exposure to air pollutants, which are difficult to ascertain. This problem is accentuated in settings where sources of personal exposure differ from those of ambient concentrations, including household air pollution environments where cooking is an important source. OBJECTIVE: The objective of this study was to assess the feasibility of estimating usual exposure to PM2.5 based on short-term measurements. METHODS: We leveraged three types of short-term measurements from a cohort of mother-child pairs in 26 communities in rural Ghana: (A) personal exposure to PM2.5 in mothers and age four children, ambient PM2.5 concentrations (B) at the community level, and (C) at a central site. Baseline models were linear mixed models with a random intercept for community or for participant. Lowest root-mean-square-error (RMSE) was used to select the best-performing model. RESULTS: We analyzed 240 community-days and 251 participant-days of PM2.5. Medians (IQR) of PM2.5 were 19.5 (36.5) µg/m3 for the central site, 28.7 (41.5) µg/m3 for the communities, 70.6 (56.9) µg/m3 for mothers, and 80.9 (74.1) µg/m3 for children. The ICCs (95% CI) for community ambient and personal exposure were 0.30 (0.17, 0.47) and 0.74 (0.65, 0.81) respectively. The sources of variability differed during the Harmattan season. Children's daily exposure was best predicted by models that used community ambient compared to mother's exposure as a predictor (log-scale RMSE: 0.165 vs 0.325). CONCLUSION: Our results support the feasibility of predicting usual personal exposure to PM2.5 using short-term measurements in settings where household air pollution is an important source of exposure. Our results also suggest that mother's exposure may not be the best proxy for child's exposure at age four.

Nitrogen oxides (NO and NO2) pollution in the Accra metropolis: Spatiotemporal patterns and the role of meteorology.

Economic and urban development in sub-Saharan Africa (SSA) may be shifting the dominant air pollution sources in cities from biomass to road traffic. Considered as a marker for traffic-related air pollution in cities, we conducted a city-wide measurement of NOx levels in the Accra Metropolis and examined their spatiotemporal patterns in relation to land use and meteorological factors. Between April 2019 to June 2020, we collected weekly integrated NOx (n = 428) and NO2 (n = 472) samples at 10 fixed (year-long) and 124 rotating (week-long) sites. Data from the same time of year were compared to a previous study (2006) to assess changes in NO2 concentrations. NO and NO2 concentrations were highest in commercial/business/industrial (66 and 76 µg/m3, respectively) and high-density residential areas (47 and 59 µg/m3, respectively), compared with peri-urban locations. We observed annual means of 68 and 70 µg/m3 for NO and NO2, and a clear seasonal variation, with the mean NO2 of 63 µg/m3 (non-Harmattan) increased by 25-56% to 87 µg/m3 (Harmattan) across different site types. The NO2/NOx ratio was also elevated by 19-28%. Both NO and NO2 levels were associated with indicators of road traffic emissions (e.g. distance to major roads), but not with community biomass use (e.g. wood and charcoal). We found strong correlations between both NO2 and NO2/NOx and mixing layer depth, incident solar radiation and water vapor mixing ratio. These findings represent an increase of 25-180% when compared to a small study conducted in two high-density residential neighborhoods in Accra in 2006. Road traffic may be replacing community biomass use (major source of fine particulate matter) as the prominent source of air pollution in Accra, with policy implication for growing cities in SSA.

Particulate matter concentration levels during intense haze event in an urban environment.

This study assessed concentration levels of particulate matter (PM) in the ambient environment of Ilorin metropolis, Nigeria, during haze episodes. Meteorological data (wind speed and direction, rainfall data, sunshine data, relative humidity and temperature) were obtained. Aerocet 531S particle counter (MetOne Instruments, USA) was used to measure four mass concentration ranges of PM (PM1.0, PM2.5, PM10 and the total suspended particles (TSP)) in 10 locations taking into consideration land use patterns. Surfer® version 8 (Golden Software LLC, USA) was used to model the spatial variation of particulate matter concentration levels using kriging interpolation griding method. Human exposure assessment was done using the total respiratory deposition dose (TRDD) estimates and statutory limit breach (SLB) approaches. The appearance of dominating weak southern atmospheric wind flow was observed as wind speed ranged from 0 to 6.811 m/s while solar radiation periods ranged from 0.3 to 3.5 h/day. The relative humidity of the metropolis ranged between 28 and 57%, while daily temperature was 15 to 36 °C. Highest concentration levels of PM measured were 73.4, 562.7, 7066.3 and 9907.8 µg/m3 for PM1.0, PM2.5, PM10 and TSP, respectively. Very strong negative correlations existed between the PM concentration levels and microclimatic parameters. Spatial variation of the concentration level as modelled using Surfer® version 8 indicated that particulate concentration level increases from south to north. Concentration levels of PM for the 24-h averaging period were generally above the 24-h threshold limit value set by the regulatory agencies for all the locations.

The Cold Dusty Harmattan: A Season of Anguish for Cardiologists and Patients.

Human health and disease often demonstrate seasonal patterns. Knowledge of these aspects aids anticipation and planning. Numerous studies have shown that hypertension and cardiovascular diseases demonstrate a seasonal pattern. The Harmattan, the cold dusty season in Sub-Saharan Africa, is the season of greatest concern in this regard. In this commentary, the author draws on his and other researchers' studies to explain the grounds for onset and worsening of existing cardiovascular diseases. As implied in the title, it is a season that puts great strain on the cardiologist and the health system, as well as greater disease burden on the patient. This should be taken into consideration in planning and pooling of resources for effective patient management and mitigation of impact of disease.

Effects of Cold-Dry (Harmattan) and Hot-Dry Seasons on Daily Rhythms of Rectal and Body Surface Temperatures in Sheep and Goats in a Natural Tropical Environment.

Studies on daily rhythmicity in livestock under natural conditions are limited, and there is mounting evidence that rhythm patterns differ between chronobiological studies conducted in the laboratory and studies conducted under pronounced natural seasonality. Here, we investigated the influence of cold-dry (harmattan) and hot-dry seasons on daily rhythmicity of rectal (RT) and body surface temperatures (BST) in indigenous sheep and goats under natural light-dark cycles. The RT and BST of the animals, and the ambient temperature (AT) and relative humidity (RH) inside the pen, were measured every three hours for a period of two days, twice on separate days during the hot-dry and the harmattan seasons, respectively. The AT and RH had minimum values of 16°C and 15% recorded during the harmattan and maximum values of 32°C and 46% recorded during the hot-dry season, respectively. A trigonometric statistical model was applied to characterize the main rhythmic parameters according to the single cosinor procedure. The result showed that RT and BST exhibited different degrees of daily rhythmicity, and their oscillatory patterns differed with the seasons (larger amplitude during the harmattan season than during the hot-dry season). The goats displayed greater (p < 0.05) amplitude of BST than the sheep in all seasons. The acrophases were restricted to the light phase of the light-dark cycle. The mesor of RT in goats was not affected by the season, but mesors of BST in both species were significantly higher (p < 0.05) during the hot-dry than the harmattan season. The goats had a more robust RT rhythm (70%) as compared to the sheep (56%). Overall, the results demonstrated that seasonal changes influenced considerably the daily rhythmicity of RT and BST in sheep and goats under natural light-dark cycle. Awareness of these changes may be useful in the improvement of diagnosis, treatment and prevention of diseases, and welfare and productivity of sheep and goats under cold-dry and hot-dry conditions.

Climate Regimes, El Niño-Southern Oscillation, and Meningococcal Meningitis Epidemics.

Meningococcal meningitis is a major public health problem that kills thousands annually in Africa, Europe, North, and South America. Occurrence is, however, highest during the dry seasons in Sahel Africa. Interannual changes in precipitation correlate with interannual changes in El Niño-Southern Oscillation (ENSO), while interdecadal changes in precipitation correlate with Pacific Decadal Oscillation (PDO). The objective of the study was to determine if there is spectral coherence of seasonal, interannual, and interdecadal changes in occurrence of meningococcal meningitis in Sahel, Central, and East Africa with interannual and interdecadal changes of PDO and ENSO. Time series were fitted to occurrence of meningococcal meningitis in Sahel, Central, and East Africa, to indices of precipitation anomalies in the Sahel, and to indices of ENSO and PDO anomalies. Morlet wavelet was used to transform the time series to frequency-time domain. Wavelet spectra and coherence analyses were performed. Occurrence of meningococcal meningitis showed seasonal, interannual, and interdecadal changes. The magnitude of occurrence was higher during warm climate regime, and strong El Niños. Spectra coherence of interannual and interdecadal changes of ENSO and PDO with occurrence of meningococcal meningitis in Sahel, Central, and East Africa were significant at p < 0.0001. Precipitation in Sahel was low during warm climate regimes. Spectra coherence of changes in precipitation in Sahel with ENSO was significant at p < 0.0001. ENSO and PDO are determinants of the seasonal, interannual, and interdecadal changes in occurrence of meningococcal meningitis. Public health management of epidemics of meningococcal meningitis should include forecast models of changes in ENSO to predict periods of low precipitation, which initiate occurrence.

Influence of season on daytime behavioral activities of donkeys in the Northern Guinea Savanna zone of Nigeria.

The present experiment was performed with the aim of investigating the effect of season on behavioral activities of donkeys during the rainy and harmattan seasons in the Northern Guinea zone of Nigeria. Sixteen apparently healthy donkeys were used as subjects and divided into four groups based on age. During each season, behavioral activities of each donkey were evaluated for three weeks using the focal animal sampling technique. The dry-bulb temperature (DBT), relative humidity (RH), and temperature-humidity index (THI) were obtained three times each day during the experimental period using standard procedures. In the rainy season, the mean DBT (31.65 ± 0.49°C), RH (73.63 ± 1.09%), and THI (84.39 ± 0.71) were significantly (P<0.0001) higher than the corresponding values of 24.00 ± 0.44°C, 36.80 ± 0.92%, and 64.80 ± 0.62 in the harmattan season. During the rainy season, the donkeys spent 60.00 ± 0.77%, 25.40 ± 0.69%, and 2.94 ± 0.21% on grazing, resting, and grooming, respectively. During the harmattan season, the donkeys spent the most time on grazing (76.76 ± 0.43%), less time on resting (11.97 ± 0.38%), and the least time on grooming (0.89 ± 0.05%). In conclusion, season and seasonal variations affect the daytime behavioral activities of donkeys in the zone, and this should be considered in husbandry practices for donkeys.

Climatology of nocturnal low-level jets over North Africa and implications for modeling mineral dust emission.

[1] This study presents the first climatology for the dust emission amount associated with Nocturnal Low-Level Jets (NLLJs) in North Africa. These wind speed maxima near the top of the nocturnal boundary layer can generate near-surface peak winds due to shear-driven turbulence in the course of the night and the NLLJ breakdown during the following morning. The associated increase in the near-surface wind speed is a driver for mineral dust emission. A new detection algorithm for NLLJs is presented and used for a statistical assessment of NLLJs in 32 years of ERA-Interim reanalysis from the European Centre for Medium-Range Weather Forecasts. NLLJs occur in 29% of the nights in the annual and spatial mean. The NLLJ climatology shows a distinct annual cycle with marked regional differences. Maxima of up to 80% NLLJ frequency are found where low-level baroclinicity and orographic channels cause favorable conditions, e.g., over the Bodélé Depression, Chad, for November-February and along the West Saharan and Mauritanian coast for April-September. Downward mixing of NLLJ momentum to the surface causes 15% of mineral dust emission in the annual and spatial mean and can be associated with up to 60% of the total dust amount in specific areas, e.g., the Bodélé Depression and south of the Hoggar-Tibesti Channel. The sharp diurnal cycle underlines the importance of using wind speed information with high temporal resolution as driving fields for dust emission models. Citation: Fiedler, S., K. Schepanski, B. Heinold, P. Knippertz, and I. Tegen (2013), Climatology of nocturnal low-level jets over North Africa and implications for modeling mineral dust emission, J. Geophys. Res. Atmos., 118, 6100-6121, doi:10.1002/jgrd.50394.