Air pollution in Kampala linked to increased risk of preterm birth

A study done by the Uganda National Institute of Public Health (UNIPH) of the Health Ministry on Kampala city has found heightened risk of preterm birth among pregnant mothers who are exposed to high levels of outdoor air pollution.

The study done between October 2021 and September 2022 also by Kampala Capital City Authority (KCCA), with Ms Mackline Ninsiima as the lead investigator, shows that researchers focused on exposure to the pollutants called inhalable fine particulate matter (PM2.5), usually found in smoke.

The report was made public on Tuesday in Kampala during the 9th National Field Epidemiology Conference.
 “Among 1,540 births, 229 (15 percent) were preterm. Overall, average gestational [or pregnancy] PM2.5 exposure was 66 microgrammes per cubic metres. Significant difference in gestational PM2.5 exposure was observed between pregnant mothers who had preterm birth and those who delivered at term,” the report reads in part.

“For every unit increase in average gestational PM2.5 exposure, risk of incidence of Preterm Birth (PTB) increased by 3 percent,” the researchers noted, adding that pregnant mothers who developed hypertensive disorders had 61 percent higher risk of experiencing PTB compared to their counterparts.

PM2.5 means the particle is 2.5 microns or less in diameter, a size which is an equivalent of a particle obtained after breaking a millet seed into 800 tiny pieces. PM2.5, usually found in smoke from gasoline, oil, diesel fuel or wood, are small enough for one to breathe them deeply into the lungs and the particles can enter the bloodstream.
Once in the body system, the particles can cause various effects in the body, including triggering preterm birth, according to scientists.  
The researchers also noted that the risk of developing hypertensive disorders during pregnancy has also been attributed to gestational PM2.5 exposure. 

They explained that this was a retrospective cohort study among mothers with singleton pregnancies at 28 weeks or beyond, who resided in Kampala City throughout their pregnancy, and delivered at Kawempe National Referral Hospital.
They also defined PTB as delivery before 37 weeks from the first day of the last menstruation period.

“We estimated gestational PM2.5 exposure based on average. PM2.5 concentration obtained from the nearest Clarity Node Solar–Powered monitor to the primary residence during pregnancy,” the researchers explained their methodology. In their report, researchers said exposure to PM2.5 concentration during pregnancy was considered as the principal predictor of PTB.

Dr Jesca Nakibuuka, a consultant neonatologist at Mulago Specialised Women and Neonatal Hospital, said the link between preterm birth and air pollution is usually due to the placenta being compromised as a result of stressors from the pollutants.

“The mother is the one that is exposed [to air pollution], constantly irritated especially [in the] airway; she is predisposed to pneumonia, may have other underlying issues like hypertension,” Dr Nakibuuka said.
“All these stressors end up affecting the baby through what we call placental insufficiency–not enough food or oxygen getting to the baby, if the mother is exposed in any way. And then eventually, this baby may have to come out if they are in distress or any form of compromise. The trigger could be the mother or baby, whichever of the two who is doing worse. It is always working around that by placenta being compromised by what is affecting the mother,” she added.  

The neonatologist called for more studies to determine the extent of the problem in the city and across the country. 
“The women we see here who deliver preterm are not only from Kampala, it is countrywide. There is a link but we need to have the figures regarding the extent of the issue in Kampala or other areas,” she said.
Dr Diana Atwine, the Permanent Secretary of the Health Ministry, said they are improving quality and access to care for preterm babies.
“In Uganda, about 14 percent of all births are preterm, which is a high number. This translates to about 200,000 [premature babies] born every year and 13,000 die before they reach their fifth birthday. They [premature babies] die because of complications related to prematurity,” Dr Atwine said.  

Ms Ninsiima said they cannot point out the exact sources of pollution.
“The source of pollution was not among the study objectives, what was reported was more of outside air pollution,” she said.
The researchers, who included the KCCA head of public health, Dr Daniel Okello, urged partners to prioritise interventions aimed at reducing air pollution to improve maternal and child health.

Mr Waiswa Ayazika, the head of environment monitoring at the National Environment Management Authority (Nema), warned that the air pollution recorded in all of Kampala was more than five times higher than the World Health Organisation tolerable limit.
However, Dr Okello said air pollution reduces during the rainy season because the pollutants are dissolved by rain.  

By 4 pm yesterday, live updates from Airqo, the air quality monitoring project based at Makerere University showed that in Kampala metropolitan area, majority of the areas (18) were in yellow (moderate air pollution), 12 were in green (good air) and two -Naguru and Bweyogerere were in Amber (unhealthy air for sensitive groups). 

Experts propose solutions

Dr Daniel Okello of KCCA said they have put in place many strategies to curb pollution in the city, including  tarmacking roads to reduce the dust and installing an air quality network. Mr Waiswa Ayazika from Nema, said besides increasing use of electric motorcycles, called for developing other cities and availing public services to control the city population. 

Dr Ivan Kimuli, a physician at Makerere University Lung Institute recommended regular servicing of vehicles and boda boda to reduce emissions. “We should walk and cycle as opposed to driving, we should use masks when entering polluted zones, proper disposal of wastes instead of burning [pay waste collectors],” he added. The expert advised city dwellers to use cleaner fuels like gas cookers and electricity, have good ventilation in the house and plant trees to absorb some of the pollutants in the air.