Air Quality Information for the North Coast
air in Humboldt, Del Norte and Trinity County is considered to be in "in attainment" of state and federal
ambient air quality standards
the State's 24-hour PM10
standard for Humboldt County only. The two pollutants of greatest concern in the region are ozone and particulate
is an invisible pollutant formed by chemical reactions involving nitrogen oxides, reactive hydrocarbons and sunlight.
It is a powerful respiratory irritant that can cause coughing, shortness of breath, headaches, fatigue and lung damage,
especially among children, the elderly, the ill and people who exercise outdoors.
Matter is fine mineral, metal, soot, smoke and dust particles suspended in the air. Primary sources of particulate
matter in the Eureka area are on-road and off-road vehicles (engine exhaust and dust from paved and unpaved roads),
open burning of vegetation (both residential and commercial), residential wood stoves, and stationary industrial sources
(factories). For health reasons, we are most concerned with particulate matter less than 2.5 microns in diameter
(PM2.5). Particles of this size and smaller can permanently lodge in the deepest, most sensitive areas
of the lungs, and cause respiratory and other health problems. The California Air Resources Board recently concluded that
PM2.5 is far more hazardous than previously estimated.
The North Coast Air Basin
North Coast Air Basin is comprised of three air districts, the North Coast Unified AQMD, the Mendocino
County AQMD, and the Northern Sonoma County APCD. The North Coast AQMD included Del Norte, Humboldt, and
Trinity Counties; the Mendocino County AQMD consists of Mendocino County; and the Northern Sonoma County APCD
comprises the northern portion of Sonoma County.
view Area Designations for the rest of the North Coast Air Basin, and all other Basins in the state, please click
. You will be redirected to the California
Air Resources Board Area Designation Maps.