An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be generated from natural or human causes. The term aerosol commonly refers to the mixture of particulates in air, and not to the particulate matter alone. Examples of natural aerosols are fog, mist or dust. Examples of human caused aerosols include particulate air pollutants, mist from the discharge at hydroelectric dams, irrigation mist, perfume from atomizers, smoke, dust, sprayed pesticides, and medical treatments for respiratory illnesses.
A tire is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, designed to match the vehicle's weight and the bearing on the surface that it rolls over by exerting a pressure that will avoid deforming the surface.
Vehicle emissions control is the study of reducing the emissions produced by motor vehicles, especially internal combustion engines. The primary emissions studied include hydrocarbons, volatile organic compounds, carbon monoxide, carbon dioxide, nitrogen oxides, particulate matter, and sulfur oxides. Starting in the 1950s and 1960s, various regulatory agencies were formed with a primary focus on studying the vehicle emissions and their effects on human health and the environment. As the worlds understanding of vehicle emissions improved, so did the devices used to mitigate their impacts. The regulatory requirements of the Clean Air Act, which was amended many times, greatly restricted acceptable vehicle emissions. With the restrictions, vehicles started being designed more efficiently by utilizing various emission control systems and devices which became more common in vehicles over time.
Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack, or propelling nozzle. It often disperses downwind in a pattern called an exhaust plume.
Diesel exhaust is the exhaust gas produced by a diesel engine, plus any contained particulates. Its composition may vary with the fuel type, rate of consumption or speed of engine operation, and whether the engine is in an on-road vehicle, farm vehicle, locomotive, marine vessel, or stationary generator or other application.
Air pollution in Hong Kong is considered a serious problem. In 2004, visibility was less than eight kilometers for 30 per cent of the year. Cases of asthma and bronchial infections have soared due to reduced air quality. However, in recent years, the hours of reduced visibility in Hong Kong have decreased by significant amounts compared to the previous ten years.
Air pollution is the contamination of air due to the presence of substances called pollutants in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. It is also the contamination of the indoor or outdoor environment either by chemical, physical, or biological agents that alters the natural features of the atmosphere. There are many different types of air pollutants, such as gases, particulates and biological molecules. Air pollution can cause diseases, allergies, and even death to humans; it can also cause harm to other living organisms such as animals and crops, and may damage the natural environment or built environment. Air pollution can be caused by both human activities and natural phenomena.
United States vehicle emission standards are set through a combination of legislative mandates enacted by Congress through Clean Air Act (CAA) amendments from 1970 onwards, and executive regulations managed nationally by the Environmental Protection Agency (EPA), and more recently along with the National Highway Traffic Safety Administration (NHTSA). These standards cover tailpipe pollution, including carbon monoxide, nitrogen oxides, and particulate emissions, and newer versions have incorporated fuel economy standards. However they lag behind European emission standards, which limit air pollution from brakes and tires.
Ultrafine particles (UFPs) are particulate matter of nanoscale size (less than 0.1 μm or 100 nm in diameter). Regulations do not exist for this size class of ambient air pollution particles, which are far smaller than the regulated PM10 and PM2.5 particle classes and are believed to have several more aggressive health implications than those classes of larger particulates. Although they remain largely unregulated, the World Health Organization has published good practice statements regarding measuring UFPs.
Air Pollution in Mexico City has been of concern to the city's population and health officials for decades. In the 20th century, Mexico City's population rapidly increased as industrialization brought thousands of migrants from all over the world. Such a rapid and unexpected growth led to the UN declaring Mexico City as the most polluted city in the world in 1992. This was partly due to Mexico City's high altitude, which causes its oxygen levels to be 25% lower. Carbon-based fuels also do not combust completely. Other factors include the proliferation of vehicles, rapid industrial growth, and the population boom. The Mexican government has several active plans to reduce emission levels which require citizen participation, vehicular restrictions, increase of green areas, and expanded bicycle accessibility.
Particulates or atmospheric particulate matter are microscopic particles of solid or liquid matter suspended in the air. The term aerosol refers to the particulate/air mixture, as opposed to the particulate matter alone, though it is sometimes defined as a subset of aerosol terminology. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health, in ways additional to direct inhalation.
Air pollution in India is a serious environmental issue. Of the 30 most polluted cities in the world, 21 were in India in 2019. As per a study based on 2016 data, at least 140 million people in India breathe air that is 10 times or more over the WHO safe limit and 13 of the world's 20 cities with the highest annual levels of air pollution are in India. The main contributors to India's particulate air pollution include industrial and vehicular emissions, construction dust and debris, dependence on thermal power for electricity, waste burning, and use of wood and dung by low-income and rural households for cooking and heating. 51% of India's air pollution is caused by industrial pollution, 27% by vehicles, 17% by crop burning and 5% by other sources. Air pollution contributes to the premature deaths of 2 million Indians every year. Emissions come from vehicles and industry, whereas in rural areas, much of the pollution stems from biomass burning for cooking and keeping warm. In autumn and spring months, large scale crop residue burning in agriculture fields – a cheaper alternative to mechanical tilling – is a major source of smoke, smog and particulate pollution. India has a low per capita emissions of greenhouse gases but the country as a whole is the third largest greenhouse gas producer after China and the United States. A 2013 study on non-smokers has found that Indians have 30% weaker lung function than Europeans.
The health of a mother directly affects the fetus during pregnancy. High levels of vehicle pollution where pregnant women reside can have adverse health effects on fetuses.
The 2013 Eastern China smog was a severe air pollution episode that affected East China, including all or parts of the municipalities of Shanghai and Tianjin, and the provinces of Hebei, Shandong, Jiangsu, Anhui, Henan, and Zhejiang, during December 2013. A lack of cold air flow, combined with slow-moving air masses carrying industrial emissions, collected airborne pollutants to form a thick layer of smog over the region. Levels of PM2.5 particulate matter averaged over 150 micrograms per cubic metre; in some areas, they were 300 to 500 micrograms per cubic metre.
The air quality in Delhi, the capital territory of India, according to a WHO survey of 1,650 world cities, and a survey of 7,000 world cities by the US-based Health Effects Institute in August 2022, is the worst of any major city in the world. It also affects the districts around Delhi. Air pollution in India is estimated to kill about 2 million people every year; it is the fifth largest killer in India. India has the world's highest death rate from chronic respiratory diseases and asthma, according to the WHO. In Delhi, poor air quality irreversibly damages the lungs of 2.2 million or 50 percent of all children.
Usage of electric cars damages people’s health and the environment less than similar sized internal combustion engine cars. While aspects of their production can induce similar, less or different environmental impacts, they produce little or no tailpipe emissions, and reduce dependence on petroleum, greenhouse gas emissions, and deaths from air pollution. Electric motors are significantly more efficient than internal combustion engines and thus, even accounting for typical power plant efficiencies and distribution losses, less energy is required to operate an electric vehicle. Manufacturing batteries for electric cars requires additional resources and energy, so they may have a larger environmental footprint in the production phase. Electric vehicles also generate different impacts in their operation and maintenance. Electric vehicles are typically heavier and could produce more tire and road dust air pollution, but their regenerative braking could reduce such particulate pollution from brakes. Electric vehicles are mechanically simpler, which reduces the use and disposal of engine oil.
Fugitive dust is an environmental air quality term for very small particles suspended in the air, primarily mineral dust that is sourced from the soil of Earth's pedosphere. A significant volume of fugitive dust that is visible from a distance is known as a dust cloud, and a large dust cloud driven by a gust front is known as a dust storm.
Rubber pollution, similar to plastic pollution, occurs in various environments, and originates from a variety of sources, ranging from the food industry processing chain to tire wear. Synthetic and natural rubber dust and fragments now occur in food, airborne as particulates in air pollution, hidden in the earth as soil pollution, and in waterways, lakes and the sea.
Particulate pollution is pollution of an environment that consists of particles suspended in some medium. There are three primary forms: atmospheric particulate matter, marine debris, and space debris. Some particles are released directly from a specific source, while others form in chemical reactions in the atmosphere. Particulate pollution can be derived from either natural sources or anthropogenic processes.
Air Quality Expert Group (AQEG) is an official committee of scientific advisers who provide independent advice on air pollutants to the UK government's Department for Environment, Food and Rural Affairs (Defra). The group is drawn mostly from academia and consists of about a dozen atmospheric chemists and other environmental scientists. AQEG also advises government officials and ministers on air quality issues, suggests priority areas for future work, and advises on changes in international policy. AQEG was created in 2001, consolidating the work of a number of previous advisory groups including the Quality of Urban Air Review Group, Airborne Particles Expert Group, and Expert Panel on Air Quality Standards.
