The population response to perceptible pollution may be pronounced when people have experienced a sharp increase in traffic and see the quality of their environment degraded.
But because of the delayed timing, it’s thought to be similar to a poison ivy reaction, which activates immune cells called helper and killer T cells and causes inflammation.
It was partly, he decided, the reaction of a healthy body to the contact with disease, and it was partly the tall grim Belsen chimney with its plume of innocent smoke.