In France, 95% of people are supplied with chlorinated tap water. Due to the presence of natural organic matter that reacts with chlorine, the concentrations of chlorination by-products (CBPs) are much higher in chlorinated water produced from surface water than from groundwater. Surface water supplies 33% of the French population. Until the 1980s, almost all surface water utilities pre-chlorinated water at the intake. Pre-chlorination was then gradually banned from 1980 to 2000. Trihalomethanes (THMs) are the only regulated CBP in France. Since 2003, THMs have been monitored at the outlet of all utilities. This study assessed current (2005–2011) and past (1960–2000) exposure of the French population to THMs. We developed an original method to model THM concentrations between 1960 and 2000 according to current concentrations of THMs, concentration of total organic carbon in raw and finished water, and the evolution of water treatments from 1960 onward. Current and past mean exposure of the French population to THMs was estimated at 11.7 µg·L⁻¹ and 17.3 µg·L⁻¹, respectively. In the past, approximately 10% of the French population was exposed to concentrations >50 µg·L⁻¹ vs. 1% currently. Large variations in exposure were observed among France’s 100 administrative districts, mainly depending on the water origin (i.e., surface vs. ground), ranging between 0.2 and 122.1 µg·L⁻¹ versus between 1.8 and 38.6 µg·L⁻¹ currently.

We present an analysis of short-term associations between ambient NO₂ and mortality according to cause, age-group, and period (cold and warm) in 18 areas in metropolitan France for the 2010–2014 period. Associations were estimated in each area using a generalized additive Poisson regression model, and effects were summarized in a meta-analysis. The percentage increase in mortality rate was estimated for a 10 µg m⁻³ increase in the NO₂ level in each area for each complete calendar year and for cold (November to April) and warm periods (May to October) in each year. We found that the NO₂ increase (lag of 0–1 days) was associated with a 0.75% increase of non-accidental mortality for all age-groups (95% confidence interval (CI): (0.4; 1.10)). During the warm period, this NO₂ increase was associated with a 3.07% increase in non-accidental mortality in the ≥75 years old group (95% CI: 1.97; 4.18). This study supports the short-term effects of NO₂ as a proxy of urban traffic pollution on mortality, even for concentrations below the maximum guideline of 40 µg m⁻³ set down by the European Air Quality Standards and the World Health Organization (WHO).

This article illustrates how a health impact assessment (HIA) can be used to promote a collaborative discussion among stakeholders as part of a local action plan aimed at improving air quality. We performed a HIA of the mortality impacts of long-term exposure to fine particles PM_2.5 in the Arve Valley in France. This narrow valley can experience high levels of pollution mostly during winter. However, local stakeholders expressed strong, contradictory opinions on the associated health impacts. Our HIA helped overcome existing silos and shifted the overriding question from “Is it true that air pollution kills people?” to “What can we do to improve air quality?” HIAs have proven to be an excellent decision-support tool in many contexts. In addition, they should continue to be useful provided that their scope, specific objectives, choices, calculation assumptions, and limitations are thoroughly explained to all stakeholders and made easily accessible.