Ozone concentrations in 2005

These data are part of the effort to provide the most detailed data on air quality
in CAPLTER. This dataset represents spatially interpolated ozone (O3) levels as
measured by monitroring stations of the Maricopa County Air Quality Department. O3
is a naturally occurring compound in which three oxygen atoms combine together. This
is an unstable combination, and ozone is continually going through a natural cycle
of being formed and then converting back to the more stable “normal� double
oxygen compound (O2). The cycle occurs fairly rapidly. In the stratosphere (6 miles
and more above the earth), naturally occurring ozone has a beneficial effect of
screening out harmful ultraviolet light from the sun. However, ground-level ozone is
a pollutant and is a major component of the brown haze that is often observed in the
Maricopa County valley. Ozone is not directly emitted into the air, but rather forms
in a complex reaction that involves heat, sunlight, and a “soup� of toxic
pollutants, especially volatile organic compounds (VOCs). Some of the most common
sources of VOCs are gasoline vapors, chemical solvents, and combustion products of
fuels and consumer products. Ozone is created by sunlight acting on nitrates (NOX)
and VOCs from motor vehicles and stationary sources, and can be carried hundreds of
miles from their origins. Ozone affects the respiratory system in people and
animals, and also affects the growth of plants.

本数据集是CAPLTER区域空气质量最详实数据采集项目的组成部分。本数据集基于马里科帕县空气质量部门（Maricopa County Air Quality Department）监测站的实测数据，经空间插值得到臭氧（O3）浓度数据。臭氧（O3）是由三个氧原子结合形成的天然化合物，其组合结构极不稳定，始终处于生成后又转化为更稳定的“常规”双氧分子（O2）的自然循环中，且该循环进程迅速。在地球上方6英里及以上的平流层（stratosphere）中，天然臭氧可有效阻挡太阳发出的有害紫外线，发挥有益的防护作用。但地面臭氧属于污染物，是马里科帕县谷地中常见的黄褐色霾的主要组分。臭氧不会直接排放至大气，而是经由涉及热量、阳光以及由有毒污染物（尤其是挥发性有机化合物（VOCs））构成的复杂反应体系生成。挥发性有机化合物（VOCs）的常见来源包括汽油蒸气、化学溶剂以及燃料与消费品的燃烧产物。臭氧由阳光作用于机动车与固定源排放的氮氧化物（NOx）和挥发性有机化合物（VOCs）而生成，可在大气中被输送数百英里之遥。臭氧会对人类与动物的呼吸系统造成影响，同时也会影响植物的生长发育。