Health and environmental impacts of toxic gases


Air pollution sources typically emit a mixture of toxic gases. For instance, wildfires, diesel engines, and other combustion processes typically release carbon monoxide, nitric oxides, volatile organic compounds, and other harmful gases to the atmosphere. Elevated concentrations of these toxic gases are harmful to human health and  the environment. For example, nitric oxide pollution forms acid rain, and carbon monoxide poisoning is a well-known health hazard.

The US Environmental Protection Agency (EPA) regulates ambient concentrations of six criteria air pollutants (NAAQS), four of which are gaseous: Carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2) and sulfur dioxide (SO2). At Distributed Sensing Technologies, we provide smart, networked sensors to monitor all of these criteria pollutants, in addition to black carbon aerosol. By accurately mapping the spatial and temporal extent of harmful gas concentrations, it is possible to ensure regulatory compliance, and ultimately develop policies that better protect the air we share.


Common gaseous pollutants

The toxic gaseous pollutants of greatest concern in urban environments include sulfur dioxide, nitrogen dioxide, and carbon monoxide. These are primarily emitted into the air by the combustion of fossil fuels such as kerosene, gasoline, and natural gas burned in power plants, cars, and other combustion driven equipment. Ozone is another important pollutant that is formed in the atmosphere when nitrogen dioxide and various volatile organic compounds undergo complex photochemical reactions.

Carbon monoxide

Carbon monoxide is a colorless, odorless gas produced when incomplete combustion occurs. It's the most common toxic gas. The main source of carbon monoxide are gasoline or diesel powered vehicles, but other sources include residential heating systems, certain industrial processes, and wildfires.

Since power plants are meticulously designed and operated to maximize combustion efficiency, they emit relatively little carbon monoxide. Carbon monoxide can cause asphyxiation at high enough concentrations and exposure times because it readily displaces oxygen in the bloodstream.

Nitrogen dioxide

Nitrogen dioxide is a reddish-brown, pungent gas that is formed when oxygen and nitrogen react at high temperatures and pressures. Nitrogen dioxide is primarily emitted by internal combustion engines (gasoline and diesel) where these extreme conditions exist. Nitrogen dioxide irritates the respiratory system, and prolonged exposure can lead to increased incidence of asthma and other chronic illnesses.

Nitrogen dioxide reacts with water in the atmosphere to form nitric acid, which contributes to acid rain. Furthermore, nitrogen dioxide is a major component of smog, creating a reddish-brown haze that is unfortunately an all too common sight in many urban areas.

Sulfur dioxide

Sulfur dioxide is a colorless gas with a suffocating odor that is emitted when burning coal or oil that contains sulfurous impurities. The vast majority of sulfur dioxide emissions come from power plants; mobile sources contribute very little. When inhaled, this noxious gas can irritate the eyes and throat, as well as harm lung tissue.

Sulfur dioxide reacts with oxygen and water vapor in the air to produce a sulfuric acid, which falls to the ground as acid rain. About three quarters of rain’s acidity can be attributed to sulfur dioxide concentrations in the atmosphere (the remaining quarter is largely due to nitric oxides). Freshwater ecosystems in innumerable lakes and streams have been harmed or destroyed by acid rain, particularly in Europe, the north-eastern United States, southeastern Canada, and parts of China. Sulfur dioxide also causes metals to corrode and the exposed stone or concrete surfaces of buildings and public monuments to deteriorate.

Impacts of toxic gas pollution on human health

Toxic gases can pose different health risks, depending on the compound or species. Potential impacts include increased incidence of:

  • Neurological disorders or illnesses.

  • Acute respiratory infections.

  • Cardiovascular diseases.

  • Birth defects.

  • Eye, nose, and throat irritation.

  • Chronic respiratory conditions, such as asthma.

  • Fertility issues.

Contact us at Distributed Sensing Technologies to help you monitor these toxic air gases the right way!