[mech987987]

>At sampling location A (highlighted in image above), which simulates conditions at the intersection of SW 5th Avenue and SW Yamhill Street, a key location in the 2 June protests, the IDLH value was continuously exceeded for a period of six minutes and twenty seconds. The maximum airborne concentration recorded at sampling location A was 443.9 mg/m³.

>At sampling location H (highlighted in image above), just one block north of sampling location A, at the intersection of SW 5th Avenue and SW Morrison Street, our simulation recorded the highest airborne concentration value across the sampled locations: 4,568 mg/m³, more than 2,000 times the IDLH threshold.

Just from knowing how gases/ aerosols disperse- the airborne concentration is extremely dependent on proximity to the particular tear gas munition that is emitting the tear gas. Any individual tear gas munition that is emitting gas at a particular moment is certain to exceed the IDLH threshold in its immediate vicinity. This article leaves out the level of detail that would be needed to know for sure whether they placed a sampling location within 6 inches of a live tear gas grenade, but the weirdly absent details following their scary citation of 2,000 times the limit sure makes me think they did.

[octokatt]

It's also worth noting that places like Pioneer Courthouse Square in Portland are sunken public spaces, which, while helpful in diffusing sound and making a nice common area, also means the tear gas will linger longer. [1]

[1] https://www.tripadvisor.com/Attraction_Review-g52024-d126568...