These are tiny bits of matter; they come from soot, dust, or other polluting sources, and can remain suspended in the air for a long time. They can lead to health problems such as asthma when inhaled.
Racial discrimination takes many insidious forms. This term refers to a situation in which industrial operations, environmental policymaking, and the enforcement (or lack of enforcement) of environmental laws unfairly impact a particular race of people, either intentionally or unintentionally. Examples include the locating of hazardous waste landfills in minority communities, and the exclusion of minorities in environmental policymaking leadership. See also, environmental justice.