27-36 Indoor Air Pollution

APES 2024

Thermal inversion

Thermal inversion

A situation in which a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below

Inversion layer

The layer of warm air that traps emissions in a thermal inversion, the warm inversion layer traps emissions that then accumulate beneath it – especially smog and particulates

Thermal inversions that create pollution events are particularly common in some cities, where

high concentration of vehicles exhaust and industrial emissions are easily trapped by the inversion layer

Under normal conditions, where temperatures decrease with increasing altitude, emissions rise into the atmosphere (Thermal inversion)

When a mid-altitude, relatively warm inversion layer blankets a cooler layer, emissions are trapped and accumulate

Worldwide, approximately 4 million deaths each year are attributable to

indoor air pollution (90% of these deaths are in developing countries, more than 50% are children)

A typical home in the US may contain a variety of chemical compounds that could

under certain circumstances, be considered indoor air pollutants

Indoor air pollutants include

• Carbon monoxide from malfunctioning heating equipment, classified as an asphyxiant (will cause oxygen deprivation)

• Asbestos formerly used as insulation in
  buildings

• Radon that seeps into homes through cracks in the foundation, groundwater, or rocks

• VOCs used in furniture, paint, and building materials

• Dust

• Smoke

Common natural indoor air pollutants

• Radon-222

• Mold

• Dust

Asbestos

A long thin fibrous silicate mineral with insulating properties, which can cause cancer when inhaled

Common human made indoor air pollutants include

• Insulation

• Volatile organic compounds (VOCs) – from furniture, paneling, carpets

• Formaldehyde – building materials, furniture, upholstery, and carpeting

• Lead - paints

Common indoor air pollutants from combustion

• Carbon monoxide

• Nitrogen oxides

• Sulfur dioxide

• Particulates

• Tobacco smoke

• Soot

• carbon monoxide

Tobacco smoke

most dangerous indoor pollutants in developed nations

Fuel burning pollution causes

1.6 million deaths/year

Common indoor air pollutants from combustion cause

Pneumonia, bronchitis, lung cancer, allergies, cataracts, asthma, heart disease, etc.

Radon- 222

• Naturally occurring radioactive gas produced from the decay of uranium found in some rocks and soils

• Can infiltrate homes as it moves up through soil

• Enters homes through the basement or cracks in walls or foundations

• Also dissolved in groundwater that enters homes through wells

Exposure to radon gas can lead to

lung cancer – second leading cause of lung cancer in US

Depending on the underlying bedrock and soils, the potential for exposure to radon exists in

houses in certain parts of the US

Sick building syndrome

a sickness produced by indoor pollution with general and nonspecific symptoms (reduced by using low-toxicity building materials and good ventilation)

Reasons for sick building syndrome

• Inadequate or faulty ventilation

• Chemical contamination from indoor sources

• Chemical contamination from outdoor sources

• Biological contamination from outside or inside