Indianapolis' large downtown fireworks display might have been canceled this year, but in many Indy neighborhoods and other local cities, the show went on — and the fireworks went off.
The sky over places such as Carmel, Lebanon, Noblesville, Cicero and Moorseville filled with colorful bursts of light. And also, in some cases, smoke, which can make it harder to breathe, especially for individuals with asthma and other respiratory conditions.
Particle pollution, or particulate matter, comes in two main sizes: PM10, short for particulate matter with a diameter of 10 micrometers, is the size of some types of pollen or mold. And PM2.5, particles with a diameter as less than 2.5 micrometers, are as fine as 3% the diameter of a human hair.
The source of those finer air pollutants is mostly related to human activities, such as driving cars, house heating, factory emissions, and occasionally, fireworks.
The mix of warm and humid air this year are also responsible for the increased levels of particulate matter seen during the holiday.
“The main peak occurs around 10 at night on July 4, and then continues on as particulates slowly get scrubbed out of the air," said Gabriel Filippelli, director of the Center for Urban Health at Indiana University-Purdue University Indianapolis. "Last year that peak was more obvious because the air quality was better. This year air quality, starting probably at the beginning of July, has been getting a little bit worse, because the heat has increased and that's made some of the particulate matter a little bit worse.”