Something like this one?

http://www.who.int/phe/health_topics/outdoorair/databases/cities/en/

I recommend chapters 5-10 of "Chemistry of the Upper and Lower Atmosphere" by J N Pitts and B J Finlayson-Pitts, Academic Press. Recent databases and journal reviews are OK as far as they go, but a good exposition of the basics like this is an essential starting point.

overview

http://www.who.int/phe/health_topics/outdoorair/databases/cities/en/

Ken

I apologise via you to Ingo: my first thought was WHO

As for your question: LIDAR is the method by which the vertical distribution of aerosol is measured. However that layering is complex and varies over the day and by season and land/sea surface.

Simplifying: most anthropogenic aerosol is emitted and formed in the surface boundary layer of the atmosphere. However there is also a substantial amount in the so-called residual layer(s) above this boundary layer.

A recent publication with info on this structuring is here

Lidar-based remote sensing of atmospheric boundary layer height over land and ocean

http://www.atmos-meas-tech.net/7/173/2014/amt-7-173-2014.pdf

Ken

The influence of aerosol on climate comes thru modelling and the modelling is confined with observations like the one I refer to.

Modelling is also necessary to discriminate between natural and manmade aerosol. Only the manmade portion changes climate

IPCC reports give the most comprehensive overview of how the aerosol effects work and how the magnitude is assessed.

I agree about modelling. There is an alternative that does as well predictively, as well as offering a physically based definition of climate, in contrast to the arbitrary 30-year rule currently in use. The 10-day to 50-year timescale isn't climate, it's macroweather. See:- 

A voyage through scales, a missing quadrillion and why the climate is not what you expect

S Lovejoy

Climate Dynamics 44 (11-12), 3187-3210

Ken

For once accept that there are branches of science in which models are the only tools. One of these areas is aerosol loadings in the atmosphere. This "compound" is short-lived and the associated aerosol fields thus change at a frequency of hours. To obtain a global average field there is only modelling. It is also the only way to assess the proportion of manmade aerosol components in the aerosol. These components are not tagged. As a support the isotope composition is measured 14C being a measure for contemporary carbon which derives from non-fossil sources.

The situation for tropospheric ozone, a single component, is somewhat similar to that for the much more complex aerosol(s). Also in this case the manmade contribution and vertical distribution must be modelled

Some articles on ambient air pollution are linked below:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6313293&queryText=ambient%20air%20pollution&refinements=4294965216&refinements=4291944246

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4378199&queryText=ambient%20air%20pollution&refinements=4294965216&refinements=4291944246

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=104779&queryText=ambient%20air%20pollution&refinements=4294965216&refinements=4291944246

I would advise you to look for research articles on major monitoring campaigns such as MINOS, STAARTE, MEDCAPHOT-TRACE, GOME, MILAGRO (a very important project) and some papers:

1) Baldasano, J.M., Valera, E., Jimenez, P., 2003. Air quality data from large cities. The Science of the Total Environment 307, 141–165. doi:10.1016/S0048-9697(02)00537-5 

2)Gurjar, B. (2014). Air quality in megacities.http://www.eoearth.org/view/article/149934

Thank you very much to all of you for your kind and generous answers and for providing wealth of information!