Wet Bulb Globe Temperature combines air temperature, humidity, wind and sun into one number for how much heat stress the conditions put on your body. It reads hotter than the air temperature on humid or sunny days, because sweat evaporates slowly and the sun adds load.
Below 20 °C WBGT we say nothing: conditions are mild. From 20 °C the session counts as warm, and from 25 °C as hot. How much that matters depends on your heat adaptation: the same hot session costs a well-adapted athlete less than one who has not trained in the heat lately.
The AQI is the US Environmental Protection Agency's measure of outdoor air, recorded where and when you trained. Up to 50 the air is clean. From 51 it is worth noting if you have asthma. From 101 fine particles can irritate the airways of sensitive athletes. From 151 a hard outdoor session costs most people more than it should. Above 200 the advice is to train indoors.
Both numbers describe the conditions, not your body. The research linking air quality to a specific slowdown is thin, so treat a high AQI as a reason to move a hard session, not as an explanation for every bad day. Compare efforts over weeks and in similar conditions.