3.2. Criteria Pollutants

So, from a regulatory point of view, we have to still finish this part. So if we look at go back to the, so here again, what are the there are large number of things that can get into air. So, like the water, we also trying to prioritize, we need to look specifically at some big impactful pollutants first before we go and investigate what else is there in the environment. So when we say the air is polluted, we need some handle on that. We cannot just say air is polluted and because I may think the air is polluted, you may not think the air is polluted, so we need some kind of reference point for that.

Criteria pollutants are specific pollutants that pose significant risks to human health and the environment. Regulatory bodies identify these pollutants to prioritize monitoring and control, as not all pollutants have the same level of impact or prevalence. The idea here is to create a reference point for evaluating air quality; this helps in establishing whether the air is considered polluted or not.

Imagine a school where teachers grade students based on their performance. If a student doesn't meet a certain grade, it signals that they may need additional help to succeed. Similarly, criteria pollutants act as 'grades' for air quality. They help identify when changes are needed to improve overall air health, just like teachers help students improve.

So again, there are large number of pollutants that are possible that can be present in the environment. So people have a criteria pollutant list and this again keeps changing, but here what is the most commonly contributing source to air pollution? It is ‘combustion’. The biggest contributor to air pollution is ‘combustion’ that’s the biggest activity where there is something that is converted and an exhaust is released.

The primary source of air pollution is combustion, which occurs when fuels are burned to produce energy. This process releases various pollutants into the air, significantly affecting air quality. Understanding these sources allows regulators to focus on controlling the most impactful contributors first, thus making it easier to reduce pollution effectively.

Think about a campfire. When wood burns, it releases smoke and gases into the air, just as vehicles and factories do when they burn fossil fuels. Understanding that the fire is producing these byproducts helps campers take measures—like moving away or ensuring good ventilation—to minimize smoke inhalation.

So from combustion, the the pollutants that that are coming out, one of the big pollutants is NOx. Then if it has sulfur there’s SO2, then there is some ozone. These are 3 big pollutants. What else comes out of combustion, ‘particulate matter’, there’s carbon monoxide. You also have other things here. So long back when this criteria pollutants started, so this I will give you a little bit of history on it.

Key criteria pollutants include nitrogen oxides (NOx), sulfur dioxide (SO2), ozone (O3), particulate matter (PM), and carbon monoxide (CO). These pollutants are recognized because they can significantly harm human health, affecting respiratory systems and leading to various illnesses. Historical context indicates that the list of criteria pollutants has evolved over time to adapt to new data and changing priorities in public health.

Consider a kitchen. When you cook, the stove releases smoke and heat, which can fill the room and affect air quality. Similarly, vehicles and industries release harmful substances that can accumulate in the atmosphere and compromise the cleanliness of air, just as a smoky kitchen makes it hard to breathe.

So, big chunk of the emissions does not have lead now. So it’s being phased out. So as long as there is no leaded petrol and there is no need for lead to be in this most of it, but it may be an environment already, that’s something that people don’t, we have to see the data.

Historically, lead was a significant pollutant primarily due to its use in gasoline. However, regulations phased out leaded petrol, leading to a decrease in atmospheric lead levels. Monitoring continues to assess existing levels of lead and other pollutants, as residual effects may still impact the environment.

Think of lead like a piece of chewing gum stuck to your shoe. Even after stepping on it and moving away, traces of it may remain. Similarly, while we've reduced lead in gasoline, it may still linger in the environment, necessitating ongoing monitoring to ensure air quality safety.

So there’s unburnt hydrocarbons. These five are definitely there as criteria pollutants, but this sixth one and then there are a few more, sometimes people use unburnt hydrocarbons is when you put a fuel, combustion doesn’t happen properly.

Unburnt hydrocarbons emerge as byproducts of incomplete combustion, and are increasingly recognized as significant pollutants. They can condense and contribute to smog and other air quality issues. Additionally, compounds such as benzene, toluene, ethylbenzene, and xylene, collectively referred to as BTEX, are also monitored due to their potential health risks and environmental impacts.

Imagine cooking a steak. If the heat is too low, the meat might not cook fully, leaving parts raw. In the combustion process, if the fuel doesn't burn completely, it releases unburnt hydrocarbons, similar to how undercooked parts of the steak can lead to health risks. Monitoring ensures that we address these 'uncooked' components in air quality.

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