Interesting article, thank you.

A note about black carbon, however - it requires a carbon based fuel. This launch vehicle (and some others too) used H2 as its fuel. As a result, we can note emissions of zero for black carbon, alumina and chlorine.

The article has one more estimation error relative to this flight. They seem to have estimated 17.5% of the landing pod's mass to burn up on re-entry. This is a reasonable estimate when re-entering from orbital flight (initial speed at least 7.8 km/s), but the flight in the news article was suborbital: a steep ascent to the Karman line (initial speed of re-entry: very low), followed by a ballistic fall.

As evidenced by photos of the capsule (also available in the news article), nearly none of its mass burnt away. It features no thermal protection tiles on the sides (there could be some under the bottom) and exhibits no visible signs of overheating or mass loss (even the painted text has remained readable).

So, while the article could be accurate in its analysis of solid-fueled and carbon-based launches and orbital re-entries, this flight differs considerably from the analyzed pattern. The capsule didn't enter orbit, didn't carry retrograde engines to initiate re-entry, as a result was lighter, and launchable using a relatively small rocket (19 m is really small for a passenger carrying rocket).

As a result, I think they caused very little harmful atmospheric emissions (I would consider water vapour harmless, thermal NOx harmful). Based on this, I would even speculate (based on intuition, no calculations) that during the flight (notes: not during the building of the spacecraft, not during spacecraft fuel production) less pollution was caused than an airliner burning aviation fuel emits over 500 km... maybe 1000 km.

It was just their energy bill that was huge.