# Tag Info

## Hot answers tagged air-quality

Accepted

### 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 ...
• 781

### 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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### How do I convert Sentinel-5p / TROPOMI vertical column density to concentration?

The unit mole / m² has dimensions count per area; the unit µg / m³ has dimensions mass per volume. To go from a quantity per area to a quantity per volume, you need to understand some properties of ...
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### 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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### The difference of vertical advection and convection process for chemistry species

The difference between advection and convection in Chemistry Transport models (CTMs) is a question of scale: Advection is driven by winds that are provided by the meteorological input dataset. Thus, ...
• 2,641

### How will air quality, weather and climate improve because of the containment, social distancing and lockdown during the COVID-19 outbreak?

This is a topic of almost continual discussion in the South China Morning Post, scmp.com , an English language newspaper in Hong Kong. This is both because air quality is a major problem in China (but ...

### 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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### 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 ...
• 12.7k
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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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### What's the minimum number of days needed for reporting a "monthly average" of daily satellite retrievals?

Provide a monthly average in every grid cell, and describe how many measurements were used for each cell. There is no fixed rule for the minimum number of days for reporting a monthly average. A ...
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### Does hydroxyl radical chemistry in air quality models create numerical stability problems?

The hydroxyl radical chemistry is not modeled explicitly in air quality models, so numerical stability is not an issue. Instead, OH is held in pseudo-steady-state. For instance, see CMAQ's ...
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### How to understand the bizarre high level for both PM2.5 and Ozone

Ozone is most closely correlated to temperature. Yes you need NOx and VOCs to create ozone, but you also need enough photolysis driven by sunlight in order for ozone to form. The day analyzed in the ...
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### Are there plants or bacteria that perform NO2 fixation and how relevant are they for improving local/regional air quality?

NO2 uptake by plants It has been observed that plants can lead to a reduction of atmospheric NO2 concentrations [Breuninger et al, 2013]. Currently, it is assumed that NO2 is taken up through stomata ...
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### Does hydroxyl radical chemistry in air quality models create numerical stability problems?

In fact, there are many chemical transport models which solve the radical chemistry without steady-state approximations. The equations are very stiff but can be integrated with suitable methods, ...
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### How Can Smog in Metropolitan Cities like Delhi & Beijing Be Reduced?

I add some information here to present the control strategies which have been done by China government. A series of paper have reported that coal combustion is the main cause of the air pollution ...
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### What are the technical solutions to measure $\ce{CO2}$ emissions?

In addition to satellite measurements of carbon dioxide, there are numerous ground based stations that also measure carbon dioxide: Italy, Hawaii, Australia, just to name a few. If you want to catch ...
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### Which types of trees clean the air best?

Evergreen trees grow faster than most hardwood deciduous trees, so their absorption and oxygen emission is greater. Note that trees do not "clean" air. Plants emit oxygen which is why air in ...
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### How is the concentration of particulate matter calculated per cubic meter

You mention "volume" which is the crux of the problem: the surface mixing layer changes height throughout the day as solar heating influences the surface. Consider that the same emission ...
• 12.7k
Accepted

### How do I convert Sentinel-5p / TROPOMI vertical column density to concentration?

What you are suggesting is possible in theory but futile for any practical purposes. The concentrations of pollutants varies vertically throughout the atmosphere, so calculating a single value that ...
• 12.7k

### What meteorological data is needed for air quality machine learning models?

From Seigneur C., Dennis R. (2011) (free access here, probably not in the final published form): Inputs to air quality models include the emission rates of primary air pollutants and precursors of ...
• 347
Accepted

### What meteorological data is needed for air quality machine learning models?

The variables needed for machine learning are different than a standard air quality model. It's actually a much shorter list because you don't have to numerically model atmospheric motion/chemistry/...
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### What is the cause for large circular areas of air pollution?

The blob near Reno Nevada is not the Anaconda copper mine, which ceased processing activities in 2000 and is currently being rehabilitated. The blob of airborne pollution is most likely due to the gas ...
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### What are the technical solutions to measure $\ce{CO2}$ emissions?

I'll add to Freds answer and just provide some detail about the satellite measurements: The keyword you're looking for is "remote sensing of the atmosphere" or "remote sensing of XYZ", where XYZ is ...

### What are the technical solutions to measure $\ce{CO2}$ emissions?

There is an EU programme having exactly this aim. See this press release. Monitoring anthropogenic CO2 emissions needs the combination of in-situ measurements, satellite observations and modelling of ...
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### How can I account for rainfall effects on air pollution?

Sounds like you want a dataset that is unadjusted for rainfall. I'm not sure what you have to gain from that, but there are ways to do it. One way to do this would be to find the inverse correlation ...
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### How Can Smog in Metropolitan Cities like Delhi & Beijing Be Reduced?

What advanced method? Stop burning fossil fuels. Run vehicles on electricity. Produce electricity using solar/wind/nuclear methods. Develop new methods. Sell methods to other countries. Profit!
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### Was rural visibility (air transparency) longer in pre-industrial times?

Pre-industrial would mean that a lot of energy use would be the in-efficient use of wood burning. I recall that part of J. S. Bach's payment at one of his posts was firewood provided by his employer -...

### How to speciate EDGAR emissions for CBMZ?

I used the R package eixport (Ibarra-Espinosa et al., 2018) to download EDGAR data (5 and spec voc 4.3.2) and then include several speciations for chemical mechanisms according to Carter (2015) and ...
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