Environmental Pollutants: Air

ENVIRONMENTAL POLLUTANTS: AIR In this infographic, we explore the different types of air pollutants and their sources, as well as highlighting how these different compounds can be monitored. AIR POLLUTANT CLASSIFICATION COMMON AIR POLLUTANTS SOURCES OF AIR POLLUTION Air pollution is the contamination of air – either indoor or outdoor – by chemicals, particulates or biological agents that differ from the natural makeup of the atmosphere. Air pollutants can be categorized as primary or secondary pollutants . Primary air pollutants are emitted directly into the atmosphere, while secondary pollutants are byproducts formed in the atmosphere as other gases or primary pollutants undergo complex chemical reactions. The World Health Organization (WHO) Global Air Quality Guidelines establish air quality standards for five common air pollutants, which have the strongest evidence to suggest public health concerns. 01_PRIMARY POLLUTANTS Particulate matter (PM) Nitrogen oxides Sulphur oxides Methane Ammonia Ozone Sulfates Nitrates Ammonium salts Secondary aerosols 02_SECONDARY POLLUTANTS Air pollutants can also be classified according to their origin (indoor or outdoor, natural or man-made) or their physical properties, for example: There are many other common air pollutants that are not formally included in the WHO air quality guidelines, but that are often presented as contaminants of concern. These include: Soot Smoke Dust Particulate matter includes coarse particles (with a diameter between 2.5 μm and 10 μm), such as pollen, wind-blown soil particles and dust from industrial activities. Finer particles (diameter less than 2.5 μm) such as the soot and chemicals generated from the burning of fuels are also included in this category. Carbon monoxide is a colorless, odor-less gas produced by the incomplete combustion of wood and fossil fuels. As an indoor air contaminant, carbon monoxide is difficult to detect without specialized equipment. Carbon monoxide can be potentially lethal to humans if exposed for a long period of time. Fixed in place Long-term data collection for compliance monitoring, enforcement, research Measurement availability for a wide variety of pollutants Many natural environmental processes can generate airborne pollutants. SURFACE DUST, SEA SALT, POLLEN AND SPORES can all be considered natural sources for particulate matter. Wind erosion can also introduce new particles into the air. VOLCANIC ERUPTIONS AND WILDFIRES can also introduce soot particles, carbon dioxide and sulfur dioxide into the atmosphere. SWAMPS AND PEAT BOGS are natural sources of the greenhouse gas methane, while lightning strikes produce significant amounts of nitrogen oxides that may go on to react with VOCs to form dangerous ground-level ozone. In urban areas, most air pollution stems from human activity, including industry and transport. ROAD TRANSPORT is the dominant source of air pollution in urban cities. Increased traffic and congestion can also increase pollutant emissions. THE COMBUSTION OF FOSSIL FUELS for transport and in industrial processes is a major source of the emission of carbon monoxide, hydrocarbons, nitrogen oxides and VOCs into the atmosphere. This mixture contributes towards the formation of more ground-level ozone, which contributes to smog in industrial areas. AIRBORNE MICROPLASTICS originating from the breakdown of plastics and synthetic clothing can enter the air and water vapor cycle, which carries the plastic particles into even the most remote areas of the world. OTHER INDUSTRIAL ACTIVITIES can produce more specific environmental air pollutants; the agricultural sector, through its use of fertilizers and rearing of animals, is a major source for methane emissions and nitrogenbased pollutants, such as ammonia and nitric oxide. Sulfur dioxide is another harmful gas that is produced mainly from fossil fuel combustion. Sulfur dioxide is the most important acidifying compound responsible for acid rain. Portable, can be used in dense, urban environments Near real-time air quality monitoring for specific priority areas Ease of use supports community and citizen science initiatives Carbon dioxide Volatile organic compounds (VOCs) Benzene Nitrogen dioxide is a reddish-brown gas produced predominately through the burning of fossil fuels. It is one of the most common indoor air contaminants, due to heating systems and cooking. It also plays a key role in the formation of atmospheric ozone. Skin flakes Fecal matter Mold Ozone in the upper atmosphere helps to protect the Earth from the Sun’s harmful ultraviolet (UV) rays. But ground-level ozone has been linked to problems with lung health. As climate change creates favorable conditions for ozone formation, combatting global ozone production is expected to be a strong focus for the coming decades. PARTICULATES PARTICULATE MATTER CARBON MONOXIDE LEAD AND LEAD COMPOUNDS RADIOACTIVE RADON GAS ULTRAFINE PARTICLES BACTERIAL MOLD FORMALDEHYDE AND OTHER VOLATILE ORGANIC COMPOUNDS (VOCS) MONITORING STATIONS NATURAL SOURCES SHORT-TERM EFFECTS LONG-TERM EFFECTS MAN-MADE SOURCES SULFUR DIOXIDE PORTABLE TECHNOLOGY GASES NITROGEN DIOXIDE BIOLOGICAL MATTER OZONE THE HEALTH IMPACTS OF AIR POLLUTION AIR POLLUTION MONITORING The WHO estimates that almost the entirety of the world’s population (99%) are breathing in air that exceeds ideal WHO air quality limits. Regularly breathing in high levels of air pollutants can be a danger to human health. Air pollution, both indoor and outdoor, was responsible for 6.9 million deaths in 2019. Long-term exposure to air pollutants has also been linked to the development of various cancers and issues with human and animal infertility. The WHO now lists data collected in more than 6,000 cities and settlements from 117 countries in their international air quality database. Traditionally, air quality monitoring has been done at fixed monitoring stations, often set up by governmental departments. But the development of new sensing technologies has also led to shifts in how air pollution is being monitored. Headache Irritated eyes Wheezing and coughing Difficulty breathing Stroke Cardiovascular disease Lung cancer Fertility problems Such low-cost, portable air pollution sensors can help support the more traditional monitoring stations by allowing researchers and citizen science initiatives to contribute real-time, in-field measurements for areas of interest – such as a city’s downtown during rush hour. Advances in wireless communication infrastructure have also made it possible for data to be collected from widely dispersed networks of small real-time sensors. In addition to ground-based monitoring, satellite mapping data can also be used to monitor changes in the concentration of carbon dioxide, methane, sulfur dioxide, nitrous oxides and other aerosols. Such satellite instruments work by detecting tiny differences in the light reflected when sunlight strikes these molecules and particles in the atmosphere.