Each row is an air pollutant, with the health system or target organ it is associated with listed beside it. Each column is a period of time. The bottom row, Total, adds all the pollutants together for that period. The number in each square is the measured level divided by the EPA screening level, written as a multiple with an “x.”

On the Kenner card, find the row for Benzene and the column for 2024. The square reads 0.011x. The health effect listed beside benzene is Immune system, meaning breathing benzene at high enough levels can affect the immune system. The number means the average benzene level in 2024 was about 1% of its non-cancer screening level — well below it. (Benzene’s cancer screening level is far lower, which is why the same benzene reads close to 1.0x on the Cancer Risk tab.) In the same column, Acrylonitrile reads 0.120x, and the Total row reads 0.190x: adding all fourteen pollutants together, the combined level was about 19% of the screening level.

Most of this tab is below the screening level. The color scale does not begin to darken until 0.75x, and almost every value sits far under that, so most of the grid appears in the palest shade. That is the finding, not a rendering problem. The exceptions are acrylonitrile at the industrial-corridor sites such as Marrero and Chalmette Vista, which approaches or exceeds the screening level in the earlier years shown. Read the numbers to compare pollutants, sites, and years.

A double asterisk (**) before a number means most of the samples behind it were below the laboratory’s detection limit, so the number is set by the detection limit rather than by the air and its true level is uncertain — anywhere from near zero up to the detection limit, not an upper bound. Hatched gray squares mean the pollutant was not measured in that period — which is different from a low reading, and so is marked differently.

For a general explanation of heat maps, see the Frequently Asked Questions.