Does traffic related air pollution cause childhood asthma

Session: New perspectives on vulnerable groups Does traffic-related air pollution cause childhood asthma? Haneen Khreis1, Charlotte Kelly1,2, James Tate1, Roger Parslow3 and Karen Lucas1 Institute for Transport Studies, Leeds Institute of Health Sciences, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds st Changing Perspectives: International Conference on Transport and Health, London, – July 2015 50 years of asthma: UK trends from 1955 to 2004 Trends in the prevalence of a diagnosis of asthma ever in children m, month; y, year Source: Anderson et al (2007) Why such steady and rapid increases? “… the increase in disease must be attributable to a change in as-yet unknown environmental factors… ” (Cookson, 2004, p 979) Source: Brook (2012) Provide data Systematic review Does children’s exposure to traffic-related Meta-analysis air pollution increase their risks of developing asthma? Learn and apply lessons Case study - The Born in Bradford Khreis et al (2014) Exposure to traffic-related air pollution and the development of childhood asthma PROSPERO 2014:CRD42014015448, available from: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42014015448 Include studies which investigate children’s exposure to traffic-related air pollution only Include human studies only and children’s studies only Include studies which investigate exposure to traffic-related air pollution or traffic-related air pollutants when road traffic is specified as their source Does children’s exposure to traffic-related air pollution increase their risks of developing asthma? Include studies which report measures of Include studies which specifically investigate the subsequent risk of association and their confidence interval asthma development in childhood precision Include observational studies only Screening process Research gaps and impact on validity: asthma definitions • • • • Heterogeneous disease No universally accepted definition Has many phenotypes AND non-specific symptoms… Research gaps and impact on validity: asthma definitions Self-report of doctor-diagnosis = 12.0% Prescription registry = 32.2% Source: Hansen et al (2012) Hospitalization registry = 6.6% Research gaps and impact on validity: asthma definitions Self-report of doctor-diagnosis = 12.0% 12 Prescription registry = 32.2% Source: Hansen et al (2012) Hospitalization registry = 6.6% Fay D, Tate J, Khreis H (2015): Investigating pedestrians PNC exposures in urban micro-environments near a busy road traffic intersection B a ckg r o u n d S i t e I n t e r s e ct i o n C o r n e r R o a d C ro s s in g I n t e r s e ct i o n C o r n e r R o a d C ro s s in g In t e r s e ct io n C o r n e r B u s St o p R o a d C ro s s in g B u s St o p I n t e r s e ct i o n C o r n e r B a ckg r o u n d S it e Research gaps and impact on validity: exposure models Fay D, Tate J, Khreis H (2015): Investigating pedestrians PNC exposures in urban micro-environments near a busy road traffic intersection B a ckg r o u n d S i t e I n t e r s e ct i o n C o r n e r R o a d C ro s s in g I n t e r s e ct i o n C o r n e r R o a d C ro s s in g In t e r s e ct io n C o r n e r B u s St o p R o a d C ro s s in g B u s St o p I n t e r s e ct i o n C o r n e r B a ckg r o u n d S it e Research gaps and impact on validity: exposure models Research gaps and impact on validity: exposure models Proximity to roadways Regulatory monitoring stations Land-use regression models Dispersion models Research gaps and impact on validity: exposure models 10 studies reporting 30 risk studies reporting 28 risk estimates, 53% were positive estimates, 93% were positive (31% significant) (65% significant) 10 studies reporting 55 risk estimates, 93% were positive (29% significant) studies reporting 40 risk estimates, 50% were positive (35% significant) 23 studies, 153 main risk estimates from exposure models, 114 (75%) positive, 45 (39%) statistically significant… and more from the other exposure models… 3 3 So does traffic-related air pollution cause asthma? “The results found across the studies followed a pattern that would be expected under the plausible assumption that the pollutants really are causally associated with asthma development, if only among a subset of children…” (HEI, 2010, p.363) But… Which pollutant(s)… But… … and why this heterogeneity? Implications • Traffic-related air pollution might have contributed to the recent asthma epidemic • Effect estimates are very likely to have been distorted/ underestimated • Many effects were detected in areas meeting the relevant air quality guidelines • Black Carbon (and ultra-fine particles) are yet unregulated Implications • Traffic-related air pollution is a modifiable environmental factor • Black Carbon (and ultra-fine particles) are truly traffic-related pollutants • -28% / -40% decreases in Black Carbon in the Milan congestion charging area (Mattioli, 2014) • A substantial proportion of asthma cases can be prevented? Thank you! References • • • • Anderson, H R., Gupta, R., Strachan, D P., & Limb, E S (2007) 50 years of asthma: UK trends from 1955 to 2004 Thorax, 62(1), 85-90 • • Health Effects Institute, H E I (2010) Traffic-related air pollution: a critical review of the literature on emissions, exposure, and health effects, Health Effects Institute • Mattioli, G (2015) Pollution or congestion charging? Air quality measures and road pricing in Milan, Italy, in Institute for Transport Studies Research Seminar Series, University of Leeds, 05 March 2015 Brook, J R (2012) 'Estimating exposure to traffic-related air pollution', in Health Effects Institute Annual Conference, Chicago, Illinois, 15-17th April 2012 Cookson, W (2004) The immunogenetics of asthma and eczema: a new focus on the epithelium Nature Reviews Immunology, 4(12), 978-988 Hansen, S., Strom, M., Maslova, E., Mortensen, E L., Granstrom, C., & Olsen, S F (2012) A comparison of three methods to measure asthma in epidemiologic studies: results from the Danish National Birth Cohort PloS one, 7(5), e36328 Khreis H, Kelly C, Tate J, Parslow R (2014) Exposure to traffic-related air pollution and the development of childhood asthma PROSPERO :CRD42014015448, available from: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42014015448 [...]... 3 1 So does traffic- related air pollution cause asthma? “The results found across the studies followed a pattern that would be expected under the plausible assumption that the pollutants really are causally associated with asthma development, if only among a subset of children…” (HEI, 2010, p.363) But… Which pollutant(s)… But… … and why this heterogeneity? Implications • Traffic- related air pollution. .. to the recent asthma epidemic • Effect estimates are very likely to have been distorted/ underestimated • Many effects were detected in areas meeting the relevant air quality guidelines • Black Carbon (and ultra-fine particles) are yet unregulated Implications • Traffic- related air pollution is a modifiable environmental factor • Black Carbon (and ultra-fine particles) are truly traffic- related pollutants... proportion of asthma cases can be prevented? Thank you! References • • • • Anderson, H R., Gupta, R., Strachan, D P., & Limb, E S (2007) 50 years of asthma: UK trends from 1955 to 2004 Thorax, 62(1), 85-90 • • Health Effects Institute, H E I (2010) Traffic- related air pollution: a critical review of the literature on emissions, exposure, and health effects, Health Effects Institute • Mattioli, G (2015) Pollution. .. Mortensen, E L., Granstrom, C., & Olsen, S F (2012) A comparison of three methods to measure asthma in epidemiologic studies: results from the Danish National Birth Cohort PloS one, 7(5), e36328 Khreis H, Kelly C, Tate J, Parslow R (2014) Exposure to traffic- related air pollution and the development of childhood asthma PROSPERO :CRD42014015448, available from: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42014015448... Pollution or congestion charging? Air quality measures and road pricing in Milan, Italy, in Institute for Transport Studies Research Seminar Series, University of Leeds, 05 March 2015 Brook, J R (2012) 'Estimating exposure to traffic- related air pollution' , in Health Effects Institute Annual Conference, Chicago, Illinois, 15-17th April 2012 Cookson, W (2004) The immunogenetics of asthma and eczema: a new focus...Fay D, Tate J, Khreis H (2015): Investigating pedestrians PNC exposures in urban micro-environments near a busy road traffic intersection B a ckg r o u n d S i t e I n t e r s e ct i o n C o r n e r R o a d C ro s s in g I n t e r s e ct i o n C o r n e r R o a d C ro s s in g In t e r s e ct io n C o r n e r B u s St ... to traffic- related air pollution only Include human studies only and children’s studies only Include studies which investigate exposure to traffic- related air pollution or traffic- related air. .. traffic- related air pollutants when road traffic is specified as their source Does children’s exposure to traffic- related air pollution increase their risks of developing asthma? Include studies which report... statistically significant… and more from the other exposure models… 3 3 So does traffic- related air pollution cause asthma? “The results found across the studies followed a pattern that would