It doesn’t simply feel more polluted when it’s hot…

Severe weather alert from weather.com:

AIR QUALITY LEVELS IN OUTDOOR AIR ARE PREDICTED TO BE GREATER THAN AN AIR QUALITY INDEX VALUE OF 100 FOR FINE PARTICLES. THE AIR QUALITY INDEX...OR AQI...WAS CREATED AS AN EASY WAY TO CORRELATE LEVELS OF DIFFERENT POLLUTANTS TO ONE SCALE. THE HIGHER THE AQI VALUE, THE GREATER THE HEALTH CONCERN.

WHEN POLLUTION LEVELS ARE ELEVATED... THE NEW YORK STATE DEPARTMENT OF HEALTH RECOMMENDS THAT INDIVIDUALS CONSIDER LIMITING STRENUOUS OUTDOOR PHYSICAL ACTIVITY TO REDUCE THE RISK OF ADVERSE HEALTH EFFECTS. PEOPLE WHO MAY BE ESPECIALLY SENSITIVE TO THE EFFECTS OF ELEVATED LEVELS OF POLLUTANTS INCLUDE THE VERY YOUNG, AND THOSE WITH PRE-EXISTING RESPIRATORY PROBLEMS SUCH AS ASTHMA OR HEART DISEASE. THOSE WITH SYMPTOMS SHOULD CONSIDER CONSULTING THEIR PERSONAL PHYSICIAN.

And this is because (source):

The stagnant atmospheric conditions of the heat wave trap pollutants in urban areas and add the stresses of severe pollution to the already dangerous stresses of hot weather, creating a health problem of undiscovered dimensions.