Each year, over 10 million people — that’s roughly the population of New York City — die prematurely because of exposure to fine particles emitted as a result of fossil
fuel combustion.

In a recent publication [1] on the health effects and regulations for particulate control, the authors say this about the US in the abstract :

“.. this approach raises the question: are we dropping the ball? As research continues to answer the remaining questions about UFP sources, exposures, impacts, and controls, the precautionary principle should call us to accelerate and expand policy interventions to abate or eliminate UFP emissions and to mitigate UFP exposures.”