Lately I’ve been reading comments by uninformed offroaders claiming that the particulate problem downwind of the off-highway vehicles is not caused by their activities on the dunes, but that it’s a natural occurrence of sand that would become airborne anyway, any time the wind blows. Apparently they are unaware of the biology of these dunes, which form crusts on the top of the sand, helping to keep it in place. Their activities break the crust, releasing particulates into the wind.
They also need to know that when it comes to particulates, size matters. The tan cloud that chokes the air here, otherwise known as “the plume,” is not the same thing as ordinary windborne sand—it is sand that has been pulverized by their vehicles, reduced into much smaller particles. These particles, also known as fugitive dust, get mixed together with diesel exhaust and other vehicle emissions, and this mixture is harmful and even deadly to breathing beings, i.e. humans, animals, and plants.
Riding back and forth over the dunes may be fun for visiting thrill seekers, but constitutes wanton destruction not only of the dunes, but of human lives. Breathing is not optional. Riding vehicles on the dunes is. The State Parks and SLO County both bear a moral and legal responsibility to put an end to this known hazard, and to abide by federal and state guidelines for environmental health and safety.
At a time when both the state and county can ill afford huge lawsuits, they should close the dunes to vehicular activity until they can prove it is not causing respiratory and cardio problems for our citizens.
This article appears in Feb 4-11, 2010.