I don't really see much wiggle room there. With the window slightly open -- and smoking for only 5 minutes -- the concentrations reached levels rated hazardous by the EPA.
Just a general comment: "Rated hazardous by government authorities" is a notoriously unreliable proxy for "actually is hazardous". For example, under current German regulations, Vitamin B12 is classified as a toxic of the highest class -- a class that requires special storage so fancy they have only a handful of them in every German State. Why did regulators falsely classify Vitamin B12 as this poisonous? Well, water pollution is often measured with the quick-and-dirty test of exposing to it a particular kind of fish, canary-in-coal-mine style. Vitamin B12 is harmless to everyone and everything -- except this particular fish, for which it is lethal even in small dosages. Faced with this fact, the agency drew the obvious conclusion....
More generally speaking, one needs expensive medical studies to figure out with confidence the actual risk from any one pollutant, Environmental protection agencies around the world lack the budget to conduct such studies for every pollutant, or even for every important one. As a result, they frequently set labels arbitrarily, according to what "feels right" to them. Just as frequently, their labeling is distorted in both directions by industrial lobbyists pushing for weaker tests, regulators covering their ässes with excessive caution, and plain absurdities like the pollution fish and Vitamin B12. All this may be acceptable for the sort of business regulation that makes up the work of the EPA. But I find it irresponsible to fine parents on such a shaky basis.
(The source for the above facts is my father. He is a biochemist working in the pharmaceutical industry, in a position where he's required to know this stuff. For regulatory policies in America, our georgeob1 is a similarly competent witness -- I'm pretty sure his story would be similar.)