Frequently Asked Question(s) - GoEnvi


  • Why do we need to monitor air quality?

    Air quality monitoring is about understanding the quality of our residential environment. This is of great importance to ensure our family and children are well protected. A good quality of the residential environment will make it more attractive and healthier to live, work and invest in. On the other hand, the degradation of the environment, through air pollution, climate change, etc., may have negative impacts on human health and well-being.

    To understand the quality of our environment, the first step is to quantify the impact by monitoring and measuring it with the environmental sensing tools.

    For example, to know the quality of the air, we measure the fine Particulate Matter 2.5 (PM2.5). If more than 35 µg/m3 of PM2.5 is detected within a day, the air quality is deemed to be unhealthy for sensitive groups and we should avoid having outdoor activities for our family.

    This comprehensive data will allow us to quickly analyze the quality of our residential environment and make prompt actions for short-term and long-term countermeasures.

  • What types of Environmental Indicators are commonly used?

    Environmental indicators are a set of numerical values that track the state of the environment over a period of time. Examples of commonly used environmental indicators include rainfall, earth surface temperature, humidity, air particular matter (PM), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO).

    Environmental indicators can be measured and reported at different scales. For example, a city may track the air quality along with the water quality and count the number of rare species of birds to estimate the health of the environment in their area. In another scenario, people living in hilly residential areas may track the variations in rainfall patterns and its impact on slope stability and soil erosion.

  • What is PM2.5 and why we should care?

    PM2.5 refers to atmospheric particulate matter (PM) that has a diameter of less than 2.5 micrometers, which is about 0.03 the diameter of a human hair. Fine particulars can come from various sources, such as power plants, motor vehicles, residential wood/leaves burning, forest fire, volcanic eruptions, agricultural burning, and dust storms. Particulars in this category are so small that they can only be detected with an electron microscope. Since they are so small and light, fine particles tend to stay longer in the air than heavier particles. This increases the chances of humans inhaling them into the bodies.

    Particles smaller than 2.5 micrometers are able to bypass the nose and throat and penetrate deep into the lungs and some may even enter the circulatory system. Studies have found a close link between exposure to fine particles and premature death from heart and lung disease. Fine particles are also known to trigger or worsen chronic disease such as asthma, heart attack, bronchitis and other respiratory problems.

    In 2013, PM was classified as a cause of lung cancer by WHO’s International Agency for Research on Cancer (IARC). It is also the most widely used indicator to assess the health effects from exposure to ambient air pollution. On a very clear and non-hazy day, the PM2.5 concentration can be as low as 5 μg/m3 or below. The 24-hour concentration of PM2.5 is considered unhealthy when it rises above 35 μg/m3.

  • What is Ozone (O3) and why we should care?

    Ozone is aninorganic molecule with the chemical formula O3. The ozone layer at the higher atmosphere (in the stratosphere) is beneficial, preventing damaging ultraviolet light from reaching the Earth's surface.

    However, low level ozone is an atmospheric pollutant. It is not emitted directly by car engines or by industrial operations, but formed by the reaction of sunlight on air containing hydrocarbons and nitrogen oxides that react to form ozone directly at the source of the pollution or many kilometers down wind.

    It is well documented that ground-level ozone can harm lung function and irritate the respiratory system. Exposure to ozone (and the pollutants that produce it) is linked to premature death, asthma, bronchitis, heart attack, and other cardiopulmonary problems.

    Long-term exposure to ozone has been shown to increase risk of death from respiratory illness. A study of 450,000 people living in United States cities saw a significant correlation between ozone levels and respiratory illness over the 18-year follow-up period. The study revealed that people living in cities with high ozone levels, such as Houston or Los Angeles, had an over 30% increased risk of dying from lung disease.

  • What is Nitrogen Dioxide (NO2) and why we should care?

    Nitrogen dioxide or NO2 is a nasty-smelling gas. NO2 primarily gets in the air from the burning of fuel. NO2 forms from emissions from cars, trucks and buses, power plants, and off-road equipment.

    Nitrogen dioxide is a major air pollutant because it contributes to the formation of photochemical smog, which can have significant impacts on human health. NO2 inflames the lining of the lungs, and it can reduce immunity to lung infections. This can cause problems such as wheezing, coughing, colds, flu and bronchitis.

    Increased levels of nitrogen dioxide can have significant impacts on people with asthma because it can cause more frequent and more intense attacks. Children with asthma and older people with heart disease are most at risk.

  • What is Sulfur Dioxide (SO2) and why we should care?

    Sulfur dioxide or SO2 is a colorless gas. It is invisible and has a nasty, sharp smell. It reacts easily with other substances to form harmful compounds, such as sulfuric acid, sulfurous acid and sulfate particles.

    About 99% of the sulfur dioxide in air comes from human activities. The main source of SO2 is the burning of coal and oil in power plants. It is also emitted by trains, large ships, motor vehicles, and other diesel equipment that burns high sulfur fuel, and by volcanic eruptions. Sulfur dioxide and nitrogen oxides can react with substances in the atmosphere to form acid rain.

    Sulfur dioxide affects human health when it is breathed in. It irritates the nose, throat, and airways to cause coughing, wheezing, shortness of breath, or a tight feeling around the chest. The effects of sulfur dioxide are felt very quickly and most people would feel the worst symptoms in 10 or 15 minutes after breathing it in. Exposure to very high levels of sulfur dioxide can be life-threatening.

    Children and the elderly, as well as people with asthma, heart or lung disease, are particularly sensitive to exposure to sulfur dioxide.

  • What is Carbon Monoxide (CO) and why we should care?

    Carbon monoxide or CO is a colorless, odorless, tasteless and highly poisonous gas. High levels of carbon monoxide can be fatal but, unfortunately, it cannot be detected by human, as it has no taste or smell and cannot be seen.

    CO is produced in the incomplete combustion of carbon-containing fuels, such as gasoline, natural gas, oil, coal, wood, and other fuels. The largest anthropogenic source of CO in most cities is vehicle emissions. It can also be released from tobacco smoke and natural sources such as volcanic eruptions and wildfires.

    Breathing the high concentrations of CO will prevent the transport of oxygen (O2) in blood around the body. The result is that vital organs, such as the brain, nervous tissues and the heart, do not receive enough oxygen to work properly. This has health effects such as headache, nausea and vomiting, blurred vision, confusion, dizziness, chest pain, weakness, difficulty breathing, damage to the heart and brain and unconsciousness.

    Carbon monoxide is most dangerous in enclosed spaces such as garages or indoor rooms.

    People with heart problems are likely to suffer from more frequent and longer angina attacks, and they would be at greater risk of heart attack. Besides, children, unborn babies, pregnant women, and elderly are particularly at higher risk for exposure to carbon monoxide.

  • What I should do if the air quality is at unhealthy level?

    When the air quality is at unhealthy level, take the following steps to reduce exposure and protect you and your family's health:

    1. Stay indoor and if possible, close all windows and openings to stop polluted air from entering.

    2. If available, turn on an air purifier that is equipped with a HEPA filter. High Efficiency Particulate Air, or HEPA air filters are usually made of fiberglass. They are 99.97% effective at removing particles as small as 0.3 microns.

    3. If available, turn on an air conditioner to circulate air and cool down room temperature.

    4. When most or all windows are closed, do not burn candle, incense or operate devices that emit smoke or gas to prevent harmful particles and gas (such as carbon monoxide) from building up.

    5. If you must drive, get an air purifier for your car that comes with at least HEPA and activated carbon filters.

    6. If you must go outdoor, make it short and quick, and wear a N95 or higher face mask. (“N95” means it can filter at least 95% of particles that do not contain oil).

    7. If the air pollution is expected to last for many days, consider moving to an unaffected location.


  • What does it measure?

    E120 Air Quality Station is a compact air quality monitoring system designed for outdoor use. It measures major air pollutants (O3, NO2, SO2 and CO)*, fine particulate (PM2.5, PM10), ambient temperature, and humidity of the surroundings.

    * Applicable for E120A model only

  • What is the difference between E120A and E120B?

    E120A is a complete set of air quality station that comes with air pollutants (O3, NO2, SO2 and CO), fine particulate (PM2.5, PM10), temperature, and humidity sensors.

    E120B is a basic air quality station that comes with fine particulate (PM2.5, PM10), temperature, and humidity sensors. Air pollutant sensors are not included in E120B.

  • How is it different to other air quality monitoring systems?

    E120 series Air Quality Station is compact in design; it has built-in GPS and wireless connectivity for timely monitoring of air quality. Air quality data are sent to a secured cloud server in real-time where a deep learning-based method is used to extract spatiotemporal air quality features for predictive analysis. User can monitor the air quality of the designated area through mobile APP, anytime, anywhere.

  • Who is using them and what for?

    Smart cities, gated residential areas, and schools. Air quality map can be generated for detecting sources of pollutants, as well as for forecasting of air quality in advance. By monitoring air quality and understanding its changing trend, we can make prompt actions to protect our family and children.

  • What are the install and setup requirements?

    Selecting an appropriate site for the Air Quality station is critical for obtaining accurate data. Here are some general tips for installation:

    Perform a Site Survey. Always perform a site survey to determine the suitable location for installation. Typically, the site should represent the general area of interest, and be away from obstructions such as buildings and trees.

    Rooftop vs. Ground Mounting. If you are going to install the Air Quality station on a roof, be careful. Injuries, roof leakage and lightning strikes can occur for roof-mounted installations. We recommend a professional roofer to assist you in the installation.

    In general, we recommend mounting the Air Quality station at least 4 feet above the roof line.

    For ground installations, we recommend mounting the Air Quality station at least 5 feet above the ground. (Our station comes with an U-bot mounting structure that can be connected to a mast or pole).

    The Air Quality station should be installed at a relatively open area, away from wind obstruction. As a rule of thumb,

    Distance to the nearest building = 4 x (Obstruction Height – Station Installed Height)

    For example, if your building is 25 feet tall, and your Air Quality station is 5 feet above the ground, install the station at a distance of 80 feet, i.e.:

    Distance = 4 x (25' - 5') = 80'

    If this clearance is not possible, you may need to install the station at a higher position, such as mounted on a post, or at a rooftop.

    Lightning. Direct or indirect lightning strikes may damage the Air Quality station, even with lightning arrestors installed. In lightning prone areas, it is recommended to install a lightning rod and connect the mast to earth ground. Consult a licensed electrician for more information.

    Birds and Rats. The Air Quality station requires an AC power supply (110/240 Vac). For wired installations, it is recommended you run the cables in electrical conduit. Rats and rodents may chew through the wires. Birds may excrement on your Air Quality station. You may want to install a decoy owl or spike strip around the station.

  • How can I view the data?

    You can view the air quality data of your surroundings through our web portal and mobile APP. Valid users will be given an online account to login and view the historical, present, and forecast data.

  • How can I be confident in the data quality?

    Before shipment, all the sensors are calibrated and tested. Each sensor is very selective to a specific type of gas. Our long term testing has shown a failure rate of < 1.3 failures per million hours of operation (FPMH). In other words, the minimum mean-time between failures (MTBF) is > 790,000 hours (or > 90 unit-years!).

  • What is the sensor lifetime? Do I need to send back for calibration?

    Under ideal conditions, all the sensors will exhibit a stable response for an indefinite period of time. For a typical environmental condition (23±3℃, 40-60% RH), a 10 year operating life is expected. On the other hand, under extreme environmental operation (e.g. continuous operation of 10 days at low relative humidity RH < 15% and high temperature at > 40℃) can cause loss of sensor sensitivity. However, loss of sensitivity is temporary, and the sensors can recover when exposed to more humid conditions.

    The Air Quality station is designed for use at ambient pressures and all sensors are calibrated under standard conditions (23±3℃, 40-60% RH, and at sea level atmospheric pressure). If your intended use is very different from the above-mentioned conditions, kindly contact us to re-calibrate the sensors before shipment. On-site service to perform periodic checking and sensor calibration is available upon request.