Huge firework displays for July 4th in US, but the nation's air quality suffers
bbc.com
bbc.com
It's the BBQ grills that are putting aerosolized greases into the air, the stuff that floats and clings and stays around.
That's where those lovely delicious smells that linger live.
BBQs aren't killing animals and releasing microplastics nor toxic smoke that pollutes the air nationally.
A better source would probaly be this observational study (https://www.sciencedirect.com/science/article/pii/S0025326X2...) and I was unable to find any high quality studies that showed any strong evidence of direct harm.
It (BBC) is just a low quality source for information impacting our lives, with an emphasis on dire-sounding, but poorly understood harms.