Question: How does air pollution effect the growth of plants and eventually when it decomposes?

Emma Markham answered on 18 Jun 2019:

There are lots of types of air pollution. One type is carbon dioxide, which adds to climate change. Increasing CO2 levels would actually benefit plants, because plants convert CO2 into O2 and uses the carbon to grow. In theory, the more CO2 would help the plant grow slightly faster. But the increase in CO2 would also make the climate hotter and drier, and so stressing the plant, stunting its growth and potentially killing the plant.
However, there are lots of other particles in the air which we normally think of when we say pollution, these can be harmful to plants in multiple ways. Firstly, plants have small pores / holes in the leaves (called Stoma) these allow the plant to do gas exchange (essentially allowing the plant to breathe) and also loose moisture to cool the leaves. These pores can become blocked with particles in the air, making it more difficult to carry out gas exchange and so limit growth. The pollution particles can also cover the surface of the leaves, blocking out sunlight and limiting the ability of the leaves to photosynthesise and so unable to gain energy from the sun and limit its growth. This is particularly easy to see when you look at plants growing along the side of a busy road or highway, because there is a lot of pollution coming from car exhausts which will coat the leaves of surrounding plants. Other types of air pollution will become acid rain, this is caused by the burning of fossil fuels which can then make rain more acidic. This can impact plants, because plants are evolved to grow in specific conditions, and so acid rain can damage their leaves and acidify the soil, stressing and killing the plant.
When a plant or animal decomposes it releases methane and carbon, this can add to global warming, this is a challenge as we need to store the carbon and not release it if we want reverse climate change. This is why you often hear about carbon sinks and ways to de-carbon the atmosphere.