"Parents warned to use pram covers to protect babies from air pollution," reports The Daily Telegraph.
The advice is prompted by a UK study where researchers simulated a normal walk to school in Guildford, involving parents pushing a pram or carrying a younger child in their arms while accompanying an older child to school. The route went through both low traffic and high traffic zones, across four traffic intersections and past a bus stop.
It used measuring instruments to assess levels of pollution at pram height and adult height.
It found that the concentrations of fine pollutant particles were higher during morning hours, particularly around traffic intersections and bus stops, while coarser particles were more concentrated in the afternoon. Fine particles are thought to be potentially more dangerous as, due to their size, they can penetrate deeper into the body's airways.
However, there was little to no difference between levels at pram and adult height.
Importantly, this research cannot demonstrate that exposure to these particles directly causes adverse health outcomes, such as respiratory diseases.
Further studies are needed to validate these findings, and possibly investigate the potential long-term implications of exposure to pollution.
The researchers recommend using barriers such as pram covers to protect children in prams from the vehicle emissions at road level, especially at traffic intersections and other traffic hotspots, and during peak traffic times.
Where did the story come from?
The UK study was carried out by researchers from the University of Surrey and the Indian Institute of Technology Roorkee. It was funded by the University Global Partnership Network (UGPN) as the work was conducted as part of the project, NEST-SEAS (Next-Generation Environmental Sensing for Local To Global Scale Health Impact Assessment).
The study was published in the peer-reviewed scientific journal Environmental Pollution.
Coverage in the UK media was both widespread and accurate.
What kind of research was this?
This was an experimental study which aimed to investigate pollution particulates that babies in prams are exposed to compared with babies carried by adults along different walking routes to school.
Children are thought to be more susceptible to environmental exposures because of their developing systems, higher inhalation rates and lower body weights.
Due to their height, children are closer to traffic emissions than adults but there has been limited research looking at this in detail. This study wanted to fill this gap.
Experimental studies like this one are useful for exploring a particular hypothesis but require validation through further research, such as studies examining varying walking routes in different urban and more rural environments. Also, this type of study can't demonstrate exposure to pollution causes health outcomes such as respiratory diseases.
What did the research involve?
The experiment was conducted to simulate a school walking route around the town of Guildford, during morning drop-off (starting at 8am) and afternoon pick-up hours (starting at 3pm). The total length of the route was 2.7km and took an average of 37 minutes to walk.
The route was designed to go through both low traffic and high traffic zones, across four traffic intersections and past a bus stop.
Instruments were placed inside a pram to measure the level of exposure to particulates at a height of 0.7m above the ground. The instruments were also carried by adults to represent the level of exposure to children being held by their parents.
The outcomes of interest were particle mass (PMC) and particle number (PNC) concentrations.
The respiratory deposition dose (RDD) was calculated by multiplying the concentration, deposition fraction (DF) and estimated ventilation rate (VR) of young babies. In other words, an estimate of the amount of particles a baby was exposed to was calculated by multiplying the number of particles, their density in a given volume of air and the expected breathing rate of a typical baby.
The results were compared between morning drop-off and afternoon-pick up, between pram and adult height measurements, and through different pollution hotspots.
What were the basic results?
There was little to no difference in the concentrations of particulates at pram-level when compared with adult height.
Small sized particles were higher during the morning drop-off compared to during afternoon-pick up and coarse particles were found to be more prevalent during afternoon hours. Correspondingly the respiratory deposition dose (RDD) for coarse particles was calculated to be 41% lower in the morning, while the RDD for fine particles was 10% higher in the morning.
The results showed high levels of coarse and small sized particles were present at pollution hotspots (traffic intersections and bus stops).
The dominant elements were found to be sodium, chlorine and iron; the sodium chloride is thought to be from road salt and iron from brake abrasion.
How did the researchers interpret the results?
The researchers concluded: "This study provides hitherto missing knowledge on the exposure of in-pram babies during the morning and afternoon pick-up periods of children from school. The findings clearly suggest much higher concentrations of fine PMC and PNC during the morning peak hours, especially on the traffic intersections and bus stand."
This study aimed to investigate the pollution that babies and young children are exposed to, whether in the pram or carried by adults, on different school drop-off and pick-up walking routes.
It generally found that the concentrations of fine particulates (PMC and PNC) were higher during morning hours, particularly around traffic intersections and bus stops.
Experimental studies like this one are useful for testing hypotheses but there are a few points worth noting:
- The study assessed a single town. They would need to compare their findings with many more assessments on different routes, and in different towns, cities and rural environments.
- Despite the media emphasis on exposure in prams, the study found that there was no difference in exposure compared with if the baby/child was carried at adult height.
- And importantly, this study has not assessed whether this exposure is actually associated with health outcomes, such as respiratory diseases. As mentioned by the authors, further studies need to assess the toxicity of particles to fully understand their effects on infants.
However, this particular study may pave the way for future research on this topic.
As lead researcher Dr Prashant Kumar suggests in an accompanying press release: "One of the simplest ways to combat this is to use a barrier between the in-pram children and the exhaust emissions, especially at pollution hotspots such as traffic intersections, so parents could use pram covers if at all possible".