The instrument
The strip above is not a legend. It is this city's own mixture, drawn by the same formula that draws the work, swept across the whole range of concentrations — from air nobody breathes to air that kills. The marker shows where the city stands right now. The green line is the level the World Health Organization considers safe.
Real position for this city, computed live. No animation, no loop: the work is dark when it is dark there.
Current PM2.5 from Copernicus/CAMS, fetched for the city itself. When the air thickens, so does the work.
There is no gradient painted here. Every point on the canvas is one particle of aerosol, carrying the colour physics gives it at that position in the sky, drifting in a flow. Where the particles crowd, the colour gathers.
The light comes from the sky — Rayleigh scattering, Mie scattering, ozone absorption in the Chappuis band, airmass along the line of sight. The colour comes from the substance: black carbon, brown carbon, mineral dust, sulphate, nitrate, sea salt, heavy metals. Each with its own single-scattering albedo, its own Ångström exponent, its own tint.
What decides which of the two wins is the poison. The fraction of the mixture that absorbs — soot, tar, metals — sets how much of each particle takes the colour of the matter instead of the colour of the sky. Reykjavik stays silver. Lahore burns.
So the work states one thing, and it states it as a formula rather than as an opinion: the more toxic the air, the more beautiful the sky. Nothing was arranged to make that true. It is what the numbers do.
Black is not a background. Black is zero particles — clean air, nothing to see, nothing to sell. The cleanest city in the collection is also the one with the least to show.
Put the forty-four in a grid and watch where the eye goes. It goes to the air that kills. I made the poison irresistible. Whoever buys is an accomplice.
For scale
Aerosol optical properties follow standard values for each species. Live concentrations come from the Copernicus Atmosphere Monitoring Service. Guideline value: WHO global air quality guidelines, 2021.
Traits of this work
Seven of the eight traits follow from the city alone and never change. Chromia is drawn from the seed. Nothing here depends on the hour: a trait that changes by itself is not a trait.