He said biological contaminants and natural toxins in foods posed a greater hazard to public health than chemical pesticides.

Many of these biological contaminants are small enough to be inhaled.

It is very difficult to completely rid such materials of biological contaminants.

A biological contaminant is released into the atmosphere and over the following years, decimates nearly ninety percent of the world's population.

Some homeowners actually add to indoor air pollution when they try to control biological contaminants by spraying insecticides.

Well water is not exposed to the same biological contaminants, and northern towns with wells make the most of them.

Sometimes insects or bird droppings can be a source of biological contaminants.

These biological contaminants can include many things.

So perhaps part of what we saw was a scarlet cloud of biological contaminant.

You started all this by suggesting that what turned the moon red was a scarlet cloud of some biological contaminant.