Underlaid — press kit

What this is

Underlaid maps cumulative environmental exposure across 2,752 neighbourhoods of Paris and its inner suburbs (INSEE's IRIS division, about 2,000 residents each; Hauts-de-Seine, Seine-Saint-Denis, Val-de-Marne): for each one, the number of categories (heat, air pollution and noise, housing, access to care) on which it is among the most affected quarter of neighbourhoods. A count from 0 to 4, not an average, set beside residents' means, measured separately.

Why a count, not an average

A blended average would hide neighborhoods that stack several distinct problems at once — exactly what this project exists to show. Counting, instead of smoothing, keeps that distinction visible.

Means to cope — a separate axis

The exposure score doesn't say who can cope. A second, separate measure does: median income, overcrowded homes and secondary residences (INSEE: income 2021, 2022 census), ranked and split into thirds of the metro area. It is never added to the score; on the map, a filter crosses the two. Highly exposed areas with the most means are mostly in Paris (heat, old housing); those with the least are mostly in Seine-Saint-Denis and Val-de-Marne (heat, air and noise). In Seine-Saint-Denis, 62% of highly exposed neighborhoods (at least 2 of the 3 exposures) are in the lowest third of means; in Paris, 4.5%. It measures means, not what households do with them (e.g. air conditioning).

The four categories

• Heat — heat vulnerability index, nearby cool places, cool green space, share of sealed ground.
• Air pollution and noise — combined exposure to air pollution and noise (Airparif and Bruitparif map).
• Housing — share of homes rated F or G on energy performance, combined with residential electrical thermosensitivity (Enedis).
• Access to care — GPs and pharmacies reachable without a car, on foot or by public transport, shared among everyone who can reach them.

Key caveats

• Income is shown for context only, never part of the score (INSEE masks 223 of 2,752 neighborhoods for privacy).
• The heat vulnerability index covers 2,618 of 2,752 neighbourhoods; the other heat indicators cover all 2,752.
• Inclusive mobility (GP access in a wheelchair) is shown for information, not scored: it compares two ways of travelling in the same place. Metro inaccessibility mostly penalises wheelchair journeys within Paris, whatever the neighbourhood's level of resources; counted in GPs within reach, wheelchair access remains lower in the inner suburbs.
• The score is an estimate that shifts with each methodological correction, not a fixed ranking — access to services left the count at launch (score out of 3), then came back in a rebuilt form, access to care (score out of 4, version 0.2, October 2026).

Current distribution — 2,752 neighborhoods (Paris + inner suburbs)