Research Focus: Air pollution
There is increasing evidence that air pollution increases the risk of respiratory, cardiac and other co-morbid conditions. A European Environment Agency report last November rated the UK the second highest in Europe, behind Italy, for deaths from nitrogen dioxide. This digest, compiled by Susan Davies, research fellow at the Centre for Research in Primary and Community Care at the University of Hertfordshire, reviews three recent papers on air pollution.
Living near major roads and the incidence of dementia, Parkinson’s disease, and multiple sclerosis: a population-based cohort study
The link between living near major roads and multiple sclerosis, Parkinson’s disease and dementia was investigated in this study carried out in Ontario, Canada.
Two analytical cohorts were used because of the different age of onset: between the ages 20-50 for multiple sclerosis and 55-85 for dementia and Parkinson’s.
Participants had lived in Ontario for at least five years and had been born in Canada.
Five distance categories from major roads were examined ranging from less than 50 metres to greater than 300 metres. Covariates included risk factors for neurodegenerative diseases, age, sex, pre-existing co-morbidities and socioeconomic status.
Long-term measures of fine matter particulate and nitrogen dioxide were obtained to examine if exposure to air pollutants and proximity to major roads could explain the outcomes.
Living closer to a major road was associated with an increased incidence of dementia,and 7% to 11% of dementia cases in those living near major roads were found to be attributable to traffic exposure. Urban residents and those who had never moved showed stronger associations.
There was no evidence linking traffic proximity to Parkinson’s disease or multiple sclerosis.
The study was limited by its inability to identify undiagnosed cases and a lack of information on how medication might have increased the risk of developing dementia.
Chen H, Kwong JC, Copes R et al (2017) The Lancet. doi: 10.1016/S0140-6736(16)32399-6.
Monitoring the effect of air pollution episodes on healthcare consultations and ambulance call-outs in England during March/April 2014: A retrospective observation analysis
Real-time national public health surveillance data such as GP consultations, ED attendances, calls to NHS 111 and ambulance dispatch calls was examined to investigate the impact of two cases of high air pollution in England.
Air quality was high at 7 (out of 1-10) on the Daily Air Quality Index scale during these episodes. Public Health England (PHE) monitored daily syndromic surveillance data on respiratory symptoms, severe asthma, wheeze and difficulty breathing was examined then broken down by age group across nine regions.
The two air pollution episodes had comparable articulate matter concentrations, but one lasted three days and the other six.
Data showed that the second episode had a greater impact on GP consultations, ED attendances and calls to NHS 111. Calls increased for asthma, wheeze and difficulty in breathing indicators, especially in 15-64 year olds.
There was little difference in air quality levels and healthcare seeking behaviour across the nine regions in England. The conclusive results showed the immediate impact of short episodes of air pollution on public health. Media reports during the second episode may have increased health consultations.
Elliot AJ, Smith S, Dobney A et al (2016) Environmental Pollution. 214, 903-911 doi: 10.1016/j.envpol.2016.04.026
Air pollution exposure in relation to the commute to school: A Bradford UK case study
Walking School Buses (WSBs) are a safe alternative to children being driven to school and they also provide daily exercise, road safety experience and reduce traffic congestion around the school.
Walking routes are usually chosen on road safety grounds with little attention given to air pollution exposure along the way.
This study compared air pollution exposure walking along the WSB route to a city school on a busy arterial road with driving along the same road.
Three adults completed the journey to and from school carrying an ultra-fine particle (UFP) count monitor to measure exposure to pollution. One drove while the two others walked on opposite sides of the road.
The results showed that the air pollution exposure for walkers was significantly higher than the car commuter during morning and afternoon journeys.
It was suggested that drivers receive lower levels of air pollution due to lower exposure and shorter journey times.
It was found that pedestrians’ exposure can be reduced most through avoiding being close to traffic queuing at junctions, walking on the opposite side of the road from the traffic and avoiding major junctions.
The findings of this study, albeit small, could be used when designing future WSBs to limit children’s exposure to air pollution.
Dirks KM, Wang JWT, Khan A et al (2016) International Journal of Environmental Research and Public Health. 13, 1064. doi:10.3390/ijerph13111064