29 votes
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What's causing this high SO2 concentrations in Kazakhstan?

The source of SO2 is the smelter associated with the Jezkazgan (Zhezkazgan, Жезказган) copper mine, mined by Kaz Minerals. The complex also produces sulfuric acid. If you check for the other ...
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17 votes
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Where do bad smells eventually go?

If you are smelling something, you are inhaling gases, particles, or a combination of the two. They don't normally build up in the atmosphere because of three reasons: transport/dilution (which you ...
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12 votes
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What is a temperature inversion and can it trap smog/pollution?

Normally, temperature broadly decreases with altitude, and convection is effective: locally warmer air will rise, and cooler air will fall. A temperature inversion is where the air temperature rises ...
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10 votes

How do current pollution levels in Los Angeles compare to the 1970s?

The air quality in Los Angeles does not meet federal air quality standards. That being said, the air quality has improved immensely since the 1970s. From the California Air Resource Board, in 1965 ...
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8 votes
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How do current pollution levels in Los Angeles compare to the 1970s?

A figure downloaded from this site. It represent the history trends of the pollutants related to the photochemical pollution from 1960s to 2000s We can find that $O_3$, $PAN$, $VOCs$, $...
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  • 2,439
8 votes
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Could a reported rainfall pH of 3.1 actually be realistic?

A quick literature search seems to confirm Gordons estimation, even at the scale of a whole bucket: [T]he annual mean pH, based upon samples collected weekly during 1970-1971 and weighted ...
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  • 476
8 votes

Which chemicals in smog obscure visibility?

Winter and Summer smog There are two types of smog: winter smog: high emissions of soot and of $SO_2$ through heating with wood, coal, etc. $SO_2$ reacts to sulfuric acid => formation of ...
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8 votes
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Convert NO2 concentration in Sentinel-5P data from mol/m2 to μg/m3 on the ground level

...measured in mol/m² within the total or tropospheric column. Is it possible to deduce concentrations for a specific slice of the troposphere? Not really, since you have a crucial bit of information ...
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8 votes
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Urgent, Please help, where can I find worldwide standards of manganese mining?

Your issue is an issue for all types of mining near residential or built up areas, not just manganese mining. The distance that mines should be from built up areas depends on the competency of the ...
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8 votes
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How is the concentration of particulate matter calculated per cubic meter

The data that you are having are called emission fluxes. If these data are available as global averages then one can calculate global mean concentration by multiplying the residence time of the ...
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7 votes
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How to remove 'silk braid' noise in satellite data?

You ask, How to remove these abnormal value for more precise data? The short answer is that you might be able to make your data look more representative of the natural 'truth', but you will probably ...
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7 votes

Could a reported rainfall pH of 3.1 actually be realistic?

Raindrops gain a small amount of acidity as they fall through carbon dioxide in the air, but that's not what this question is about. Raindrops commonly start off as ice crystals which have to nucleate ...
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7 votes

What causes smog to clear up on some days?

My guess would be a combination of boundary layer, cloud cover, and emissions (though that isn't terribly specific). Smog is a combination of nitrogen oxides (which cause smog's brown color), ozone, ...
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  • 1,361
7 votes

How much worse is the typical subway air, compared to street-level air pollution, in a typical city?

Depends on what type of pollution you are talking about Moreno et al., 2015 studied this problem in Barcelona, and compared Metro (subway) to trams, buses, and walking in various parts of the city. ...
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7 votes
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How can agricultural ammonia lead to PM2.5 production in the atmosphere?

Acid/Base Chemistry Gaseous ammonia (NH$_3$) acts as a base when it dissolves in water. The reactions are below. NH$_3$(g) + H$_2$O(l) $\rightleftharpoons$ NH$_3$(aq) NH$_3$(aq) + H$_3$O$^+$(aq) $\...
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6 votes

What is a temperature inversion and can it trap smog/pollution?

As others have noted, a temperature inversion is a layer where temperature increases with height. This is called an inversion because the normal temperature profile decreases with height. A ...
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6 votes
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What's the background concentration of trace gas/pollutants?

Background pollution is what would be measured if no anthropogenic emissions existed. In other words, if you shut off human activity (or avoid the emissions from it), you can measure the background. ...
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6 votes

How to understand the bizarre high level for both PM2.5 and Ozone

I think it is important to keep in mind the mechanisms that form PM$_{2.5}$ are different than the mechanisms that form O$_3$. From the data your provided you can draw some simple conclusions: ...
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6 votes

Why are inversion layers so important in meteorology?

Farrenthope is correct, but I would like to add some detail. An inversion occurs when the air is warmer than the ground. It is called an inversion because it is the opposite of what occurs during the ...
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6 votes
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Are these plane trails seen from satellite

Under the right conditions (in a basic sense, locally high relative humidity; see also this discussion on this site regarding contrail formation), the clouds initially formed by contrails may persist ...
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6 votes
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Would home heat pumps provide large benefits against climate change?

The values on the DEFRA table with the column heading $ kg\ \ce{N2O} $ already include the global warming potential (GWP) factor of 298, as indicated by a note on the column heading (looking at ...
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  • 1,340
5 votes

How to remove 'silk braid' noise in satellite data?

Thanks for @Kwinkunks's answer. I have read this paper. And this figure may explain something important. What I have already done is plotting the original data like the first subplot. From Destriped -...
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  • 2,439
5 votes

Why are inversion layers so important in meteorology?

Temperature inversions are important to meteorology and pollution because they are the boundary for atmospheric mixing. If there is a strong inversion, the air above and below an inversion do not ...
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5 votes
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How can I test the Air Quality?

The AQI calculation does not require that all pollutants be measured. Instead, it uses the pollutants that are available and then uses a function (chosen by the overarching regulatory agency) that ...
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  • 12.7k
5 votes
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Convert OMI NO2 Vertical Column Density (molecules/cm^2) into Mixing Ratio (ppm)

No, you shouldn't really do that. A vertical column density (VCD) retrieval provides the user with a representation of the total number of molecules over some vertical slice (e.g. the entire ...
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5 votes

How Can Smog in Metropolitan Cities like Delhi & Beijing Be Reduced?

The first thing to do is to stop putting pollution in the air, particularly very small particulate matter that are produced by combustion. For the Beijing Olympic Games of 2008, the Chinese ...
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5 votes
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Which particles are classified as PM2.5? How exactly is this defined?

I think answering your questions in reverse will make more sense. The "size" of PM is typically the aerodynamic/inertial impaction size, as you guessed. My standard reference for this is this paper. ...
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  • 1,361
5 votes

Are atmospheric halogen oxides "supposed to be" in the atmosphere? Where do they come from?

Classifying the presence of halogen oxides in the atmosphere as either natural, pollution or mixed bag, would result in mixed bag. Natural sources of halogen oxides include the ocean and volcanoes. ...
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4 votes
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Does usual city pollution have effects on relative humidity?

By way of reference, "humidity depends on water vaporization and condensation, which, in turn, mainly depends on temperature". From the information you have supplied in your comments. There are ...
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4 votes
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Why are "ground level" air quality monitors really on rooftops?

In order to put your question in perspective, you need to consider atmospheric mixing and the size of the system you are curious about. The troposphere is several kilometers thick and the mixed layer ...
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