A few thoughts on that. Unleaded started in 1975. I’d like to know when it reached 50% of the vehicles but googling doesn’t give me that. Assuming 20 years for the entire fleet to turn over, that would give 1985 for 50%. I think you want 25% or less leaded cars until you don’t have too much lead in the air, so that goes to about 1990. The pollution didn’t end immediately at the city limits, so the burbs that would be built on the next mile or so would still be on polluted land. So I think that gets you to houses built 1995+ to even 2000+ to get to uncontaminated land (depending on how fast your city was growing).
I know around here the houses with decent backyards were built in the 70s to 80s. In the 90s the yards were getting small, and nowadays they are almost nonexistent. So the best suburbs for chickens are 80s and earlier. Which is also the contaminated land.
Last thought is that they keep saying that there is no safe level of lead exposure.
A few thoughts on that. Unleaded started in 1975. I’d like to know when it reached 50% of the vehicles but googling doesn’t give me that. Assuming 20 years for the entire fleet to turn over, that would give 1985 for 50%. I think you want 25% or less leaded cars until you don’t have too much lead in the air, so that goes to about 1990. The pollution didn’t end immediately at the city limits, so the burbs that would be built on the next mile or so would still be on polluted land. So I think that gets you to houses built 1995+ to even 2000+ to get to uncontaminated land (depending on how fast your city was growing).
I know around here the houses with decent backyards were built in the 70s to 80s. In the 90s the yards were getting small, and nowadays they are almost nonexistent. So the best suburbs for chickens are 80s and earlier. Which is also the contaminated land.
Last thought is that they keep saying that there is no safe level of lead exposure.