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>> The EPA's own studies have shown that to prevent a measurable decrease in IQ for children deemed most vulnerable, the standard needs to be set much lower, to

by wffurr 5y ago

>> The EPA's own studies have shown that to prevent a measurable decrease in IQ for children deemed most vulnerable, the standard needs to be set much lower, to 0.02 µg/m3. The EPA identified avgas as one of the most "significant sources of lead". Atmospheric lead is pretty dangerous, more so than encapsulated lead paint inside a wall.

lazide 5y ago
That’s an incredibly misleading quote - do you have anything that can correlate atmospheric lead concentrations at ground level with flight hours or take/offs and landings somewhere?
- edrxty 5y ago
  I was curious so here's some napkin math Assumptions: - moderately busy airport, three Cessna 172s concurrently in the pattern during the day @7gph - no significant wind - 7gph3cessnas2glead/gallon=42grams of lead/hr - The lead sinks as the combustion products are far heavier than the atmosphere. To reach 0.02ug/m^3 you'd need to dilute it in approximately 1000m x 1000m x 2000m of air which is well beyond the boundaries of a typical airport of this type. Honestly this seems pretty plausible.
  - lazide 5y ago
    Hmm, thanks for doing the math! I don’t think that is that far off the boundaries of typical GA airports, and for those that are smaller they are almost always in the middle of nowhere with no inhabitants around them. One of the more concerning types of GA airports is something like Reid-Hillview, which is surrounded on all sides by residences - and even has an elementary school right on it’s border. It’s 750mx1200m - and a lot of it’s pattern is going to be over a much, much wider area. Altitude wise, it’s going to be between 1-4 thousand feet most of the time too. So it’s almost certainly going to be diluted well below that level, even if there is zero air movement, which there always is? It will be spread over a wider area of course, but if concentration is the concern, you’d probably only have higher amounts somewhere like the flight line?
sneak 5y ago
Note that the word most is not in the quote from the source.

by wffurr 5y ago

lazide 5y ago

That’s an incredibly misleading quote - do you have anything that can correlate atmospheric lead concentrations at ground level with flight hours or take/offs and landings somewhere?

edrxty 5y ago
I was curious so here's some napkin math Assumptions: - moderately busy airport, three Cessna 172s concurrently in the pattern during the day @7gph - no significant wind - 7gph3cessnas2glead/gallon=42grams of lead/hr - The lead sinks as the combustion products are far heavier than the atmosphere. To reach 0.02ug/m^3 you'd need to dilute it in approximately 1000m x 1000m x 2000m of air which is well beyond the boundaries of a typical airport of this type. Honestly this seems pretty plausible.
- lazide 5y ago
  Hmm, thanks for doing the math! I don’t think that is that far off the boundaries of typical GA airports, and for those that are smaller they are almost always in the middle of nowhere with no inhabitants around them. One of the more concerning types of GA airports is something like Reid-Hillview, which is surrounded on all sides by residences - and even has an elementary school right on it’s border. It’s 750mx1200m - and a lot of it’s pattern is going to be over a much, much wider area. Altitude wise, it’s going to be between 1-4 thousand feet most of the time too. So it’s almost certainly going to be diluted well below that level, even if there is zero air movement, which there always is? It will be spread over a wider area of course, but if concentration is the concern, you’d probably only have higher amounts somewhere like the flight line?

sneak 5y ago

Note that the word most is not in the quote from the source.