The research team, led by Uebari Korfii of Rivers State University, conducted a cross-sectional assessment across indoor wards, outdoor grounds, and nearby traffic junctions at the selected teaching hospitals. Using a RASI700 BIO Portable Gas Analyzer, an ISO-certified handheld instrument, they took rapid spot measurements lasting between 30 and 120 seconds at breathing height, roughly 1.2 to 1.5 meters above the ground, with triplicate readings at each microenvironment. The pollutants tracked included carbon monoxide, nitric oxide, nitrogen dioxide, sulfur dioxide, methane, hydrogen sulfide, volatile organic compounds, and fine particulate matter known as PM2.5.

The measurements revealed clear spatial patterns. Carbon monoxide ranged from 1.0 to 4.4 parts per million, nitrogen dioxide from 0.4 to 1.2 ppm, sulfur dioxide from 0.2 to 1.0 ppm, and volatile organic compounds from 9.4 to 12.1 ppm, with methane reaching as high as 9.5 ppm and hydrogen sulfide between 6 and 9 ppm. Indoors, volatile organic compounds accumulated to their highest levels, a signature of the cleaning agents, disinfectants, and laboratory solvents used routinely in clinical settings. Outdoors and at junctions, nitrogen dioxide and sulfur dioxide dominated, pointing to vehicular traffic and the diesel generators that Nigerian hospitals depend on because of unreliable grid electricity.

To untangle the sources of this pollution, the team applied principal component analysis, a statistical technique that identifies which pollutants vary together and therefore likely share origins. Two principal components captured essentially all of the variance in pollutant concentrations at each hospital, with the first component explaining between 56.7 and 64.6 percent. At different sites, the dominant loadings shifted among nitrogen oxides, sulfur dioxide, hydrogen sulfide, volatile organic compounds, and particulate matter, indicating a mixture of combustion sources, waste decomposition, and hospital operational activities. Cluster analysis reinforced this picture, grouping junction sites as the most polluted and separating one hospital, Aminu Kano Teaching Hospital, with a distinctly different pollution profile from the others.

The health risk calculations were the most striking part of the study. Using the hazard quotient, which compares measured concentrations against reference values from the United States Environmental Protection Agency, the researchers found that nitrogen dioxide, sulfur dioxide, and hydrogen sulfide each exceeded the safety threshold of one across all microenvironments. Sulfur dioxide posted a mean hazard quotient of 28.67, nitrogen dioxide 7.13, and hydrogen sulfide an extraordinary 8,152.53, driven by emissions from sewage systems and waste treatment areas. By contrast, carbon monoxide, methane, and PM2.5 remained below unity. Because the hazard index sums the individual quotients, the cumulative index exceeded one everywhere the team measured, signaling potential combined non-carcinogenic risks from simultaneous exposure.

Acute exposure estimates told a similar story. Relative risk values for nitrogen dioxide ranged from 3.06 to 60.26 across sites, peaking at one hospital’s outdoor environment, while sulfur dioxide relative risks spanned 1.32 to 4.53. PM2.5, by contrast, showed a relative risk of exactly 1.0, suggesting that fine particle levels during the monitoring window were not high enough to trigger acute effects. The authors caution that these figures reflect instantaneous spot measurements rather than long-term exposure, so they represent screening-level indications of short-term risk rather than a full chronic assessment. Even so, the consistency of the signals across five hospitals is difficult to dismiss.

The air quality index results were equally sobering. Several environments, including indoor and outdoor areas at Aminu Kano Teaching Hospital and outdoor and junction zones at Ahmadu Bello University Teaching Hospital, plus the junction at one Katsina facility, registered AQI values above 300, the hazardous category. Most remaining sites fell into the very unhealthy range, with sulfur dioxide and nitrogen dioxide driving the scores. For facilities that house some of the most vulnerable people in any community, patients with compromised lungs and immune systems, newborns, and the elderly, such readings represent a paradox: environments intended for healing may be actively contributing to respiratory irritation, asthma exacerbation, and cardiovascular strain.

The sources of the pollution are largely identifiable and, in principle, addressable. Diesel generator exhaust, medical waste incineration, open waste burning, sewage systems, and nearby traffic all emerged as contributors, and the study documented how close generator houses and waste disposal areas sit to patient wards. The authors argue that routine air quality monitoring, improved ventilation in wards and laboratories, better waste management, and stronger regulatory enforcement are essential to reduce the risks. They also frame the work within Nigeria’s commitments to the Sustainable Development Goals on health, sanitation, and sustainable cities, noting that empirical data on hospital air quality in the region had been almost entirely absent until now.

The study’s limitations are acknowledged candidly. Spot measurements of 30 to 120 seconds capture snapshots, not seasonal or diurnal patterns, and the risk assessment did not incorporate exposure duration, frequency, or individual susceptibility. Longer-term monitoring would be needed to characterize chronic risks fully. Nevertheless, as a first systematic comparison of indoor, outdoor, and junction microenvironments in Nigerian hospitals, the research provides a baseline that health authorities cannot easily ignore. If the air outside a hospital junction can register as hazardous, the authors suggest, then protecting the air inside the wards must become an explicit part of hospital environmental health policy rather than an afterthought.

Subject of Research: Air pollutant distribution and health risks in hospitals in Northwestern Nigeria

Article Title: Assessment of air pollutant distribution patterns and potential health risks in hospitals in Northwestern Nigeria

Article References: Korfii, U., Ndokiari, B., Konne, L. J., & Kalagbor, I. A. (2026). Assessment of air pollutant distribution patterns and potential health risks in hospitals in Northwestern Nigeria. BMC Environmental Science, 3(1), Article 15. https://doi.org/10.1186/s44329-026-00056-8

Image Credits: AI Generated

DOI: 10.1186/s44329-026-00056-8

Keywords: air pollution, hospital air quality, Northwestern Nigeria, nitrogen dioxide, sulfur dioxide, hydrogen sulfide, volatile organic compounds, health risk assessment, air quality index, diesel generators, indoor air quality, environmental health