Urban air quality

China’s progress in the improvement of air quality masks a widening gap: its heavily polluted, industrial border cities bear a disproportionate health and economic burden, which demands urgent policy shifts to avoid deepening environmental injustice.

Very short-lived convective dust events in urban areas are not always captured by traditional air quality monitoring in the USA; finer temporal scale measurements are needed to avoid health risks being overlooked

Forest fragmentation by urban expansion creates plumes that enhance ozone production, according to analyses of combined field observations and modelling over South China.

Cloud coverage over cities is increasing, especially those in developing countries, with coastal cities in tropical climates exhibiting the most significant increases, according to analyses of global-scale satellite cloud coverage data.

Long-term observations show that a rising fraction of ammonium nitrate in PM_2.5 reduces aerosol acidity, suppressing the heterogeneous conversion from NO₂ to HONO. This weakens its contribution to the HONO source and atmospheric oxidation capacity.

Rapid particle nucleation and growth in Houston are explained by sulfuric acid, base, and low volatility organics in the urban atmosphere, according to measurements of nucleation precursors and box model simulations.

Globally, urban areas experienced increases in ozone concentrations from 2005 to 2019, whereas fine particulate matter, nitrogen dioxide, and fossil-fuel carbon dioxide emissions showed non-significant variations, according to analysis of large geospatial air pollution datasets.

Big-data empowered traffic signal control in China can reduce vehicle trip times, creating potential reduction of 31.73 million tonnes (Mt) of CO2 emissions annually and US$31.8 billion benefits per year.

Cities and urbanization concentrate benzene, a carcinogen and brain toxin found in petroleum. This study estimated associations between benzene exposure and brain disorders in urban adults in the UK, finding elevated risks of dementia, major depression and anxiety disorder even at low benzene levels.

Nationwide implementation of a series of stringent multisectoral air pollution prevention and air-quality monitoring policies in China was associated with reduced hospital admissions for a wide range of cardiorespiratory, neuropsychiatric and kidney diseases due to substantial reductions in PM_2.5 and black carbon pollution over a period of 5 years.

Ozone pollution is enhanced by increased non-combustion anthropogenic volatile organic compound emissions during heatwaves, according to atmospheric measurements and modelling of ozone concentrations in a heatwave in Shanghai.