What is the Importance of an Air Quality Sensor, and is it Worth Buying?

Did you know that the WHO estimated that air pollution was responsible for the premature deaths of 4.2 million people worldwide in 2019? Clean air is essential for our health everywhere. From our homes to cities, keeping the air pure is necessary. Pollutants such as PM, CO, NO2, and SO2 can directly affect human organs.

Detecting pollutants consistently and accurately is the first step to improving air quality. The lurking invisible threat claims millions of lives worldwide. Air quality sensors are indispensable for public health alerts and personal air filtration. So, let's start exploring the hazards of air pollution, why detecting air quality is essential, and what makes air quality sensors worth buying!

The Hazards Of Air Pollution

Air pollution affects everything, from individuals' health to global economies. Understanding the effects of this far-reaching silent killer is vital to making progress against its elimination and keeping ourselves safe.

▪ Health Impacts of Air Pollution

Numerous well-reported effects of pollution on human health exist. Poisonous particles can be smaller than human air or a grain of sand. These are invisible to the human eye and only detectable using air quality sensors. These particles pass through our nose or mouth down through the trachea. A bronchi then takes them to either side of the lungs, distributing them into thinner passageways called bronchioles. At the end of bronchioles, there are alveoli. The air pollutants can penetrate the walls of the alveoli and enter our bloodstream.

Air pollutants inside our bloodstream can reach our lungs, heart, brain, and other vital organs. Scientists have found that these pollutants have led to stroke, lung cancer, asthma, chronic and respiratory diseases in the human body.

▪ Environmental Effects

Air pollution also has direct impacts on the environment. Pollutants from nearby sources can settle on the ground via dry deposition. Similarly, direct deposition to the ground or acid rain can occur in case of rain or precipitation. Unfavorable ground conditions directly affect our ecosystem.

The condition favors species that are tolerant to excess nutrients, thereby diminishing the diversity and richness of plant species. The animal communities also change, causing them to migrate.

▪ Economic Consequences

Increasing pollution can have economic impacts on countries. These include rising healthcare expenditures, decreased workforce efficiency, a drop in crop yield, and a drop in tourism. Countries that solely rely on tourism have the most impact. The government must regulate industrial releases and promote clean energy technologies. Using air quality sensors in industrial areas for regulatory concerns can enhance surveillance and decrease pollution.

Types of Air Pollutant

According to the World Health Organization (WHO) global air quality guideline, PM2.5, PM10, Ozone, Nitrogen Oxide, Sulfur Dioxide, and Carbon Monoxide are primary pollutants in the air. However, air quality sensors go a step ahead and can detect volatile organic compounds and ammonia. Pollutants can be outside or inside our living spaces. Here are all the types of contaminants and their associated hazards:

• Primary Pollutants

➔ Carbon Monoxide (CO): As a pollutant, CO causes a drop in oxygen levels in the blood. Fatigue, headaches, confusion, and dizziness are common CO symptoms in the bloodstream.

➔ Nitrogen Oxides (NO_x): High levels of NOx gases in the air can cause health and environmental effects. NOx in the air affects respiratory, cardiovascular, and aggravation conditions. It also causes acid rain and forms ozone on ground level by reacting with other pollutants.

➔ Sulfur Dioxide (SO₂): Like NOx gases, sulfur dioxide has similar health and environmental effects. It also contributes to smog, which can reduce visibility and directly affect economic activities. 

➔ Ozone (O₃): Ozone at ground level is known to cause chest pain, coughing, throat irritation, and congestion. It is not a direct product; instead, it forms through combining NOx and VOCs.

➔ Ammonia (NH₃): Ammonia is a severe health hazard, as it can cause blindness and death in humans. It can also cause tree leaves to burn in the wind direction of the polluting source.

➔ Hydrogen Sulfide (H₂S): The toxic gas hydrogen sulfide (H2S) has serious health effects. Even low concentrations can irritate the eyes, nose, and throat. Long-term exposure can cause headaches, dizziness, nausea, and pulmonary edema. At high concentrations, H₂S can kill in minutes.

➔ Chlorine (Cl₂): Chlorine can cause respiratory problems in humans but is primarily part of CFCs. It contributes to the ozone layer's depletion and causes soil or groundwater contamination.

• Particulate Matter (PM)

Particulate matter is similar to sand particles but much more complex in structure and invisible to the naked eye. It is produced mainly through incomplete combustion. Car exhaust, industrial stacks, crop burning, and some natural phenomena can cause the production of particulate matter.

They contain arsenic, organic carbon, lead, sulfates, nitrates, and black carbon. Air quality sensors can detect this particulate matter and provide a warning for dwellers. These are primarily three types of PM. Each of them is based on the size of the particulate. Here are their sizes:

PM₁₀ <10um

PM_2.5 <2.5um

PM_1.0 <1um

• Other Gases

Volatile Organic Compounds (VOCs), indicated by the TVOC and CH₂O (formaldehyde), also contribute to the respiratory, neurological, and long-term health effects. They also form ozone at ground level and cause acid rain. Advanced air quality sensors can detect TVOC and CH₂O levels in the air at 10ppb resolution.

Why Air Quality Detection Is Important?

★ Outdoor Air Quality

Detecting pollution using air quality sensors early on can help avoid negative impacts. The government can systematically approach the burden pollutants can cause on the healthcare system. Similarly, policymakers can analyze air pollution to impose penalties and track sources of pollution. Here is a table that provides safe levels as per WHO research:

Air Quality Guideline Level by WHO

Researchers can use air quality detection to provide meaningful data to help regulators and industrialists avoid polluting the environment. On a smaller scale, air quality detection in homes, such as PM detectors, can help prevent major health issues affecting kids and adults.

★ Indoor Air Quality

Lack of ventilation with modern air conditioning systems or regions with cold climates can cause indoor air quality challenges. There are multiple sources of pollutants indoors. On an industrial scale, where there are loads of combustion processes, material production, or manufacturing, there is always a chance that the air quality within the facility will degrade. Air quality sensors in confined indoor spaces can indicate ventilation requirements, filter replacements, or process errors.

How The Air Quality Sensor Can Help Detect The Invisible Threat?

Now that we know the importance of air quality sensors, we can understand how they work. Let's start with the types of sensors that you may encounter:

Types Of Air Quality Sensors

● Indoor: Particulate matter and carbon dioxide sensors are famous for household applications. They use the photoelectric phenomenon to detect pollutants in the air.

● Outdoor: Multifunctional air quality sensors are ideal for outdoor use. They can detect up to 20 atmospheric parameters, including primary pollutants, particulate matter, and volatile compounds. A typical outdoor detector also uses a photoelectric phenomenon to detect pollutants.

● Specific Pollutants: To be affordable, manufacturers may also produce air quality sensors that target only a few pollutants that one may want to observe.

How Sensors Work?

There is a general approach to detecting gases in the air. These air quality sensors also use a similar photoelectric phenomenon for detection.

1. Passing Light from the Gas

The process starts by taking a sample of air and passing it through the sensor's chamber. The chamber has a light source, either a laser or infrared. The light passes through the gas and falls onto the photoelectric detector on the other end.

2. Checking Absorption of Light

The particle absorbs light, or the gas particle absorbs infrared radiation. This results in lower absorption on the other end by the detector. Different absorption rates at different frequencies represent the respective gas molecules.

3. Generating a Signal

The photoelectric cell will detect the light on the other end of the passing air. It converts light into an electric signal. The intensity of the electric signal represents the quantity of pollutants in the air.

Interpreting Air Quality Data

● Data Acquisition and Processing

Air quality sensors generate an electric signal as an output by passing lights of different wavelengths through the air passing through it. High-end sensors can convert this analog output into a digital one, such as RS485. Some provide direct results in the form of voltage or ampere.

● Data Interpretation and Analysis

The results go into the microprocessor, which then uses the signal from the detector to produce results that users can interpret. The output can be in:

○ Pollutant Concentration: μg/m³, or Parts per Billion (ppb)

○ Temperature: Degrees Celsius (°C) or Fahrenheit (°F)

○ Pressure: Pascals (Pa), millibars (mbar), or inches of mercury (inHg)

○ Humidity: Percentage (%) or grams per cubic meter (g/m³)

○ Flow rate: Liters per minute (L/min) or cubic meters per hour (m³/h)

○ Force: Newtons (N)

● Comparison with Safe Levels

Now, we can compare these outputs with safe levels defined by organizations such as the World Health Organization (WHO), the United States Environmental Protection Agency (EPA), and the European Union (EU).

Conclusion

Using an air quality sensor is vital in modern-day environmental conditions. 99% of the world's population lives above the pollutant limits defined by WHO. Air quality sensors can detect air pollutants in parts per billion, starting from 0 to 6000 ppb. They have excellent measurement accuracy, linearity, repeatability, interoperability, and consistency. Do not hesitate to buy an air quality sensor for indoor or outdoor, industrial or domestic use; they are the first step to fighting pollution.

FAQ

1. What does an air quality sensor mean by ppm or μg/m³ pollutants?

Air quality sensors represent the presence of gas pollutants in the air by parts per million (ppm) and show particulate matter (PM) in the air by micro-gram per cubic meter (μg/m³). Government organizations and WHO provide safe pollutant limits in ppm and μg/m³. It's simply the presence of gas molecules in milligrams per liter of air volume, which is also ppm.

2. What are the limits of air quality sensors for detecting pollutants?

High-end air quality sensors such as the Rika RK300-08 can sense up to 14 gas molecules and 3 particulate matter types. The sensor's minimum detection capability depends on its resolution. These high-end sensors can detect PM as low as 1μg/m3 and sulfur dioxide as low as 0.1ppm in the air.

3. Can air quality sensors detect gases and pollutants in my house?

There are multi- and single-air quality sensors that can detect civil gases and pollutants indoors. PM and civil gases such as methane, carbon monoxide, and aldehydes are present in homes that use combustible gases in the kitchen. Particulate matter can also enter through our ventilation and accumulate. Indoor air quality sensors can detect these gases and provide warnings for abnormal levels.