Our warming climate is amplifying environmental and human health problems in urban areas. Heat island effects, flooding, droughts, altered pollutant transport patterns, and human respiratory stress are examples of interactions between macro- and micro-climates that impact urban areas. The share of the global population living in cities is expected to rise to 80% by 2050, compared to 55% today. Emissions from energy production and other anthropogenic activities are altering the physical and chemical properties of the atmosphere and are linked to climate change, increased pollution in urban areas, and human health problems. This SBIR project will develop three new, low-cost, networkable aerosol measurement systems suitable for deployment in urban areas. The system avoids problems with current approaches that are too large and costly. Specifically, the project will support the development of: a light absorption device to measure black carbon and other absorbing aerosol, a sizing and counting device to measure aerosol number size distributions, and an automated filter sampler for aerosol chemical composition measurements. Phase I of the project will develop new designs and prototypes of the devices to minimize cost, size, weight, and power consumption. Prototypes will be tested with known particle sizes and chemical properties and under ambient urban conditions to assess performance. A small network of the devices will be deployed to test cloud data acquisition and analysis tools Commercial applications and other benefits include creating new, cost-effective tools to study aerosol climate forcing and urban micro-climate/larger scale feedbacks, creation of data sets to validate urban airshed pollutant transport models, and to perform measurements in health effects studies.