Scientific and socio-economic issues

Atmospheric pollution has a major and proven effect on (cardiovascular and respiratory) mortality and morbidity everywhere in the world. In 2012, one out of every nine deaths (7 million) in the world was due to (outdoor and indoor) air pollution-related conditions. Of those deaths, around 3 million are attributable solely to ambient (outdoor) air pollution. Air pollution represents one of the biggest controllable environmental risk to health, and reducing air pollution could save millions of lives. In Europe, air pollution is causing around 467,000 premature deaths every year and in France, 48,000 deaths are attributed yearly to particulate matter (PM) exposure. Much less is known regarding the effect of early life (prenatal and early postnatal) exposure to atmospheric pollution. These questions relate to the more general DOHaD (Developmental Origins of Health and Diseases) concept. Research, in particular from members of MobilAir consortium, showed that PM pregnancy exposure is likely to decrease birth weight. Longer-term effects of maternal pregnancy exposure to atmospheric pollutants are less well known but recent studies suggested that pregnancy exposure to atmospheric pollution could be associated with postnatal growth, respiratory function and neurodevelopmental problems.

The proven health impacts of air pollution corresponded to a cost of $1.7 trillion in OECD countries in 2010, while specifically in France, the direct and indirect economic cost is around € 100 billion. In China plus India, estimates amount to $ 1.8 trillion/year.
Public policies are thus required to reduce the health and economic impacts of air pollution. The focus in many countries should be on the main pollution sources, i.e. road traffic and heating. Such public policies can combine different instruments: norms on emissions for vehicles; economic incentives to increase the share of non-motorized mobility and of public transports and to favour technological change toward low emission vehicles; actions to increase public awareness; modifications of urban infrastructures and of dwellings (e.g., insulation, heating modes…). Most of these levers can be triggered at the city level. Nevertheless, until now, the adoption of such public policies did not allow to significantly and quickly alleviate the above-mentioned societal burden, in particular in France.

One possible reason is that policies to reduce pollution are often dimensioned without explicit consideration of a targeted health impact. At the best, they rely on an ex ante environmental evaluation ignoring any health consequence. Starting from a target health impact to appropriately dimension urban policy measures would be a logical and important change of approach. It raises scientific challenges, implying to develop a reverse approach consisting of starting from a target formulated in terms of improvement of health (e.g., a reduction by 20% in PM-related mortality) and subsequently identifying policy measures allowing to reach such a health target. Such an approach would be of great relevance to decision-making.

In order to be efficient on pollution levels, many urban measures imply a large compliance of the population. However it is clear that developing e.g. bike lanes is not always enough to strongly increase bike use. Mobility behaviours are complex and are not determined only by cost of transport, time spent in transportation, and transport offer. Individual drivers related to altruism, perceptions and social norms as well as habits also play a role. It is thus important to improve the comprehension of mobility behaviours. Identifying if subjects being offered adapted alternative (cleaner) transportation modes can adopt these modes, and if not, understanding which obstacles exist, would be very innovative. Evaluations should also consider noise, physical activity, quality of life and confront social inequality in terms of exposure to pollution, sanitary and economic impact of public policies.

Cities in Europe and elsewhere have undertaken measures to limit air pollution emission, especially from transportation and heating sources. In France, ZAPA (low emission zones - LEZ) had been planned, but abandoned. A reason put forward was that such measures were deemed socially unequal (with the more deprived people being disproportionally touched by traffic restriction measures). However, very few, if any, rigorous evaluations of any social inequality in cost (and also benefit) of low emission zones have to our knowledge been conducted. In cities where ambitious programs were implemented, environmental evaluations have documented decreases in PM10 by as much as 50% in Tokyo between 2001 and 2010, and between 5% and 13% in Germany. In Berlin and Munich, the decrease in soot concentrations was larger than that of PM. This evaluation is one of the few that considered other characteristics of PM than concentration. ADEME’s review of LEZ in Europe shows that only in rare cases was the environmental evaluation supplemented with a Health Impact Assessment, or HIA. Estimating the cost of the measures taken by the local authorities would also be very important, and would allow conducting cost-benefit analyses of such policies. In the USA, analyses of benefits and costs of the Clean Air Act law are planned by the law and indicate that the benefits exceed costs by a factor of 30 to 90. No such figure is available in France. Making such figures available in the French and European context, where atmospheric pollution standards are much higher than in the USA (regulatory limit of 25 µg/m3 for PM2.5 yearly concentration in Europe, compared to 10 in the USA), would be very relevant for citizens and decision makers.

Grenoble (urban area of about 500,000 inhabitants) is the main city located inside the Alps. It is one of the French cities with high air pollution exposure (mean yearly population PM2.5 exposure, 18 µg/m3). The vast majority of residents (96%) are exposed to an average PM2.5 level higher than the WHO guideline (10 µg/m3, Figure 1). These high levels are partly explained by the basin configuration of Grenoble, the low winds, specific winter meteorological conditions (low mixing height) and frequent use of old (inefficient) wood heating stoves. One member of the MobilAir consortium recently evaluated the health impacts of air pollution exposure, concluding that PM2.5 exposure is responsible of an estimated 3% to 10% of non-accidental mortality cases and lung cancers. Grenoble Metropole has undertaken several measures (Figure 2) to improve air quality through the Ministry of the Environment’s program « Breathable cities within 5 years». The plan targets transportation of goods and mobility and non-efficient individual wood heating