What Fraction Of Nox Emissions Are Natural

Is sulfur dioxide considered a green house gas?

One word answer would be NO.But sulfur dioxide is sometimes classified as indirect greenhouse gas. The paragraph below will help you in getting better insight.Any gas in atmosphere that absorbs and emits radiant energy within the thermal infrared range is qualified to be considered as greenhouse gas. GHGs that occur both naturally and from human activities include →Water vapor, Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O) and ozone (O3). Other GHGs that occur from human activities include → fluorinated gases: chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HCFCs), bromofluorocarbons (halons), perfluorcarbons, PFCs, nitrogen trifluoride, NF3, and sulfur hexafluoride, SF6. These are either side products of industrial processes or manufactured for human needs (as cleaning agents, refrigerants, and electrical insulators).Now there are some gases that are classified as Indirect Greenhouse GasesThe indirect greenhouse gases contribute to global warming by:- producing direct greenhouse gases through reactions with other chemical compounds, or through their own chemical transformations;- influencing the atmospheric lifetime of other greenhouse gases;- affecting absorptive capacity of atmosphere as influencing cloud formation (which are major non-gas contributor to Earth’s greenhouse effect).Such gases include non-methane volatile organic compounds (NMVOCs), nitrogen oxides (NOx) comprised of nitrogen monoxide (NO) and nitrogen dioxide (NO2), carbon monoxide (CO) and sulfur dioxide (SO2).But here also, there are some doubts about role of sulfur dioxide in warming the earth.Sulfur dioxide plays its indirect role by contributing to the formation of aerosols (exceptionally small particles of dust, salt or liquid droplets) by coupling with ‘elemental carbon’, affect warming and cooling in the earth’s atmosphere as:- Aerosols scatter the sun’s radiation and send it back to space, help in cooling the atmosphere.- They also affect the climate by increasing clouds’ lifetime and thickness and decreasing water droplet size, while increasing water droplet concentration in the atmosphere, which warms the atmosphere ( water droplets is a GHG).Now, whether the net effect is of cooling or warming is debatable as there effect is difficult to quantify because they have short atmospheric lifetimes, and their concentrations and compositions that vary regionally, spatially, and temporally too.Hope, its clear to you :)

What is the United States doing to restrict carbon dioxide emissions?

As far as I know, the US has a LOT of natural gas (often a byproduct of fracking for oil), which is being employed by market forces to replace a relatively high percentage of coal burning power production. This is not so much a “restriction” per se, but rather a market driven response to the relatively low price of natural gas. Markets are usually much more effective at driving changes in behavior than top down government regulations which often generate more negative unintended consequences. Natural Gas can easily be argued to the best source of energy given its very clean burning. There are so few real pollutants that are generated from its burning (most households use it for the heating of water for example), and the ability of natural gas fired plants to perform “load following” is far superior to nuclear. Finally, although some accidents do occur (all forms of energy have some risk - life is risky), it is extremely safe.By the way, natural gas emits about half as much CO2 (not a pollutant) as coal for the same amount of energy generated (more hydrogen being burned as a fraction of the total energy) and there is far less real pollutants such as NOx, SOx and particulates as compared to coal.I hope that this helps,Ian

How much haze is caused by air pollution?

I can't give any specific answers, and my answers are more appropriate for large urban areas rather than the rural areas you asked about...  But can offer a few notes.One pathway to ozone production which causes a lot of smog is when NOx from combustion engines mixes with VOCs like isoprene emitted by plant life (forests).  Plant life isn't by any means the only source of VOCs, you also get them from agricultural fields, and some industrial activity, but I thought this was a good example where "natural" and anthropogenic emissions mix to create smog/haze.Also, there have been laws banning the burning of coal in cities since 1272 when King Edward I banned the burning of sea-coal. London's Historic "Pea-Soupers" .  This was due to the haze, but also the odour.

What is the point of having electric cars, that are run from fossil fuel generated power stations and not solar, when the world is supposedly trying to reduce its carbon footprint?

There are several good reasons.First, there are also many non-fossil (and non-CO2-producing) sources of electricity: hydroelectric, nuclear, geothermal, wind and solar are all significant. Electricity represents the only practical way to use these energy sources for land transportation. In 2016, California generated more than half of all its electricity from these non-fossil sources.Second, even when fossil fuels are used to power electric vehicles, they do so more efficiently than internal combustion vehicles. Heat engines have an inherent economy of scale, i.e., larger engines are generally more efficient. This is true even when you include the losses in power lines and in battery charging and discharging.Electric and hybrid vehicles can also recover some of their energy through regenerative braking, with pure electrics doing it better than hybrids.Third, electricity generation uses a wider range of fossil fuels than car and truck engines. In fact, hardly any utility-scale electricity generation in the US burns petroleum because it is so expensive relative to coal and natural gas. Some vehicles (notably transit buses) do burn natural gas but it cannot be liquified at room temperature so it must be carried as a high pressure gas.Fourth, emissions are much more easily “scrubbed” from a relatively few, large fossil-fuel-burning generating plants than from millions of small vehicle engines. Other than CO2, the only significant emission from natural gas-fired electricity generation are NOx (oxides of nitrogen), but their levels are still far below those of gasoline and especially diesel vehicle engines. Even with catalytic converters, gasoline engines also produce large amounts of carbon monoxide and diesel engines are particularly notorious for producing smoke.