Around two months ago, with Cayman’s traffic hitting a historic peak, Cayman Compass journalist Michael Klein began testing the island’s air quality as part of a long-term project. Since that experiment began, a massive fire at the George Town landfill along with the ban on cruise ships and a sharp drop in vehicle use under the COVID-19 lockdown rules, have offered telling insight into how these factors affect the environment. In a special feature today, we look at the quality of the air we breathe and the impact it is having on the health of everyone in Cayman.

‘O land of soft, fresh breezes’ is not only the first line of Cayman’s national song, ‘Beloved Isle Cayman’, but it is also a misconception, because Cayman’s air is at times not as pure and fresh as commonly believed.

This assessment is based on air-quality tests conducted over several weeks using a retail sensor. The measurements were taken before and during the lockdown due to COVID-19, as well as in the aftermath of the dump fire early last month.

The results might be somewhat surprising, at least to those not suffering from asthma or exhibiting other sensitivities to air pollution.

Cayman’s air-quality measurements show for the most part low-to-moderate exposure to air pollution over a 24-hour period. However, during specific times of the day, air pollution tends to rise to levels noticeable by those who have respiratory issues, reaching occasional peaks that are harmful to everyone.

Air quality sometimes worse than London

Example of the air quality in London on average weekday. Green and yellow denote low and moderate air pollution.

The data shows that on an average day, Cayman’s air quality is, of course, much better than that of the smog-infested heavy-industry hotspots of China, India and Southeast Asia. But at certain times of the day, the air is not even as clean as in inner-city London during rush hour.

Cayman resident Ian Tyler, who divides his time between Grand Cayman and the UK, says he noticed that his mild exercise-induced asthma never improved when he was on island, even though air quality seemed to influence his symptoms on skiing trips, for example.

“I had assumed the Cayman air would be very clean compared to London,” he said.

Because he has to consider when to go out for exercise, regardless of where he is in the world, Tyler uses an inexpensive air-quality-measuring device to get a better idea of pollution levels.

Air quality example in Cayman. Red and purple indicate high to very high pollution levels.

“I’ve been surprised by how high some of the pollution readings are in Cayman,” Tyler said. “I really did expect pollution in this wonderful Caribbean island to be low.”

Although he has not done an extensive comparison and his observations are based on limited data, he said the results on the west side of Cayman are routinely worse than during a regular busy weekday in the centre of London. The results are lower, however, during northwesterly winds and the air is much cleaner in East End, he said.

The spot-check results taken by the Cayman Compass over several weeks, prior to the COVID-19 outbreak, confirmed these observations.


Measuring air quality

The quality of the air that we breathe is generally expressed on the scale of the standardised air quality index, or AQI, which allows for the comparison of results in different locations for specific air pollutants.

Anything below 100 AQI is considered to be a low or moderate health concern. Levels between 100 and 150 are regarded as unhealthy for sensitive groups. And readings higher than 150 constitute anything from unhealthy to downright hazardous for the general population.

During specific times of the day, particularly from late morning to early afternoon, when there is a lot of sunshine and traffic on the roads, general pollution levels in Cayman can rise to between 70 and 150 AQI, with occasional peaks at around 200 AQI.

While Cayman does not have much industrial activity nor the population density of larger metropolises, it can be a hot and dusty place with a high volume of traffic. As it turns out, these are precisely the factors that influence the quality of the air that we breathe on Grand Cayman.

Dr. Archita Joshi-Bhatt, a pulmonologist at Health City Cayman Islands, says compared to urban areas in India, where she has practised before, complaints about air quality from her patients are not that common.

“Except more recently, following the dump fire, there were people having asthma flares because of the smoke and particulate matter in the air,” she noted.

The highest pollution readings occurred the day after the landfill fire for particulate matter.

Those days also produced the highest pollution readings of all the spot checks. On 11 March, the highest reading of 296 AQI was recorded in the centre of George Town, next to Eden Rock, downwind from the landfill.

The general trends in Cayman that Joshi-Bhatt observes are related to seasonal changes, which can cause different individual responses. While some may react to cooler air, often a trigger for asthma, others feel worse when it is more humid.

On 11 March, the highest reading of 296 AQI was recorded in the centre of George Town, next to Eden Rock, downwind from the landfill.

High pollution readings recoded around dusty locations, like parking lots and construction sites, do however contribute to cases in her daily practice. Air pollution related to dust particles in these areas is not unusual, she said.

“We do have people in the construction industry and people working in demolition, who do complain of respiratory symptoms and associate some of these problems with dust in the environment.”

She is, for example, treating several patients with asthma who attribute a worsening of their symptoms to construction-related activities.

Types of air pollution

Particulate matter – tiny solid particles that can be smaller than 2.5 microns and penetrate airways and lungs, causing harm – is one of the most prevalent air pollutants in Cayman. Particulate matter is also considered a risk factor for cardiovascular and respiratory diseases, as well as lung cancer.

However, high levels of particulate matter are not necessarily manmade. They also occur in arid areas and on Cayman’s beaches, often in combination with strong winds.

In addition, nitrogen dioxide (NO2) is a predominant suffocating and irritating gas commonly found in the air. It comes mainly from combustion engines used in cars, boats and electricity generation. High levels of NO2 can decrease lung function and cause bronchitis and asthma, especially in children.

Our air also includes ozone, a gas that is beneficial in the higher levels of our atmosphere but harmful at ground level. Ozone is created in a chemical reaction between two pollutants, the oxides of nitrogen and volatile organic compounds, in the presence of intense sunlight. The gas is most likely to reach unhealthy levels on hot sunny days in urban areas, when breathing ozone can cause chest pain, coughing, throat irritation and inflammation of the airways.

Our air quality depends on the amount of these pollutants and varies depending on the location, meteorological conditions, the time of day and the season.

Wind, for instance, can help dissipate some of the NO2 but also increase the amount of particulate matter in the air. At night, in the absence of human activity and ozone-producing sunlight, the air is generally much cleaner.

One reason that the highest air pollution levels around noon and in the early afternoon go largely unnoticed by the general population is possibly that they coincide with the hottest time of day when most people do their best to avoid the oppressive heat and thereby also reduce their exposure to bad air quality.


Central George Town, particularly in the port area, saw higher values than West Bay or East End, most likely as a result of differences in traffic density and construction activity.

In addition to the hot sunny climate and dry, open land without vegetation, traffic is a significant contributor to pollution levels in Cayman, both in terms of NO2 and ozone levels.

Assessing the air quality earlier this year during daily commutes showed that in the morning pollution levels were not as high as in the late afternoon, when traffic-related pollution had time to build up for several hours, supported by hot sunny weather.

Measuring the air quality along the same route at about the same time while walking, riding a bicycle and driving a car, it became apparent that sitting inside a vehicle does not offer protection from exhaust fumes and other air pollution. NO2 levels were slightly higher in a car, with the windows closed and the air conditioner on. The reason for this is that the outside air is sucked into the car largely unfiltered, and then recirculated in the vehicle; outside, bad air can dissipate.

Joshi-Bhatt said how long someone is exposed to air pollution matters a lot. If we were regularly stuck in traffic for a long time, this could lead to health issues. If it were for just half an hour, it may not have such a dramatic impact on somebody with healthy lungs. But not everybody is susceptible to the same type of exposure in the same way.

People who are predisposed to having respiratory problems should definitely avoid getting stuck in traffic for a prolonged period of time, she said.

The current lockdown has significantly lowered the traffic volume in Cayman, with noticeable effects, particularly in George Town, spot checks have shown. The combination of the remaining traffic and hot sunny days, however, does still produce high, if not harmful, NO2 levels.

Even during the lockdown, air pollution levels, as in this case NO2, can at times be high.

These measurements taken on 17 April show that even during the lockdown NO2 pollution can be high as indicated by the red colour.

Cruise ships

One factor that has not been considered during the lockdown is the emissions generated by cruise ships.

A 2017 study by campaign group Transport & Environment found that the 203 cruise ships that operated in European waters at the time emitted a combined total of 62 kilotons of sulfur oxides per year. This was substantially more than the 3.2 kilotons generated by all of Europe’s 260 million registered cars. Cruise lines described the results of the study as unscientific.

However, an air-quality report for the environmental impact assessment of the proposed cruise berthing facility in Cayman noted in 2015 that, locally, cruise-ship emissions were between 10 and 30 times higher than traffic emissions.

The report contained the results of air-quality measurements at six locations in George Town over three months. It found that UK Ambient Air Quality Standards were not exceeded for both NO2 and SO2 during the sampling period.

But the results were not absolutely conclusive as some were estimates based on the measurements, and particulate matter was not quantified. The analysis also did not include a worst-case analysis or dispersion modelling.

The report nevertheless noted that while the converted results do not exceed the UK AAQS values, the one-hour NO2 values approach upwards of 90% of the standard value. “This leaves little ‘space’ for increased impacts from changes at the cruise terminal,” the authors concluded.

How we measured air quality

The retail air-quality sensor we used is a device called Flow. It would not be used for scientific field studies, although Plume Labs, the developer of the Flow, says its accuracy is within 90% of industrial devices.

The set-up, frequency and timing of the tests were also not at the level of scientific experiments. Instead, the intention was to provide a snapshot of different factors affecting the air that we breathe every day.

What pollutes our air?

Particulate matter – solid particles that can penetrate the airways and lungs because they are smaller than 10 microns (PM10) and even 2.5 microns (PM2.5) in diameter.

Nitrogen dioxide – a suffocating and irritating gas mainly generated by combustion engines.

Volatile organic compounds – carbon-based gas molecules that in high concentrations can cause irritation and decreased breathing capacity.

Ozone – harmful ground level ozone is created in a chemical reaction between volatile organic chemicals, carbon monoxide and nitrogen oxides in the presence of sunlight.

Sulphur dioxide – a toxic gas that is created by industrial activity and the burning of heavy fuels, for example on ships.


The air quality index

The air quality index is an international standard that allows the comparison of results in different locations. Anything below 100 AQI is considered a low or moderate health concern. Levels between 100 and 150 are regarded as unhealthy for sensitive groups. Higher than 150 constitutes anything from unhealthy to hazardous for the general population.

Plume developed its own AQI. The thresholds are:

0-20: Low pollution.

21-50: Moderate pollution – air quality is considered acceptable.

51-100: High pollution – this threshold is above the 24-hour exposure limits recommended by the World Health Organization. Everyone may start to feel adverse health effects, and those with sensitivities should take care when performing outdoor activities.

101+: Very high pollution – in these conditions, everyone may start to experience more serious health effects, with long-term exposure representing a real health risk.

The air-pollution measurements taken in Cayman show for the most part low-to-moderate exposure to air pollution over a 24-hour period. However, during specific times of the day, particularly from late morning to early afternoon when there is a lot of sunshine and traffic, both PM2.5, PM10 and NO2 levels tend to rise above 50 AQI with occasional peaks well in excess of 100 AQI.

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  1. Michael, thanks for covering this important topic. Its very good air quality issues in Cayman are being exposed. I would like to take this opportunity to raise awareness of the terrible influence of gas powered landscaping equipment, specifically leafblowers. According to a report: gaspowered leafblowers will produce more ozone pollution in the state of California than that of all cars combined in the state. There are good alternatives to these devices such as simply raking or how about just leaving the leaves on the ground to provide nutrients to the soil and something for the insects. For those who cannot depart from their leafblower there are also commercial grade electric leafblowers that go up to 6 hours without a charge. Leafblowers also produce terrible noise pollution that travels for hundreds of meters. Many cities, states and countries across the world have already banned them or are in the process of doing that. Cayman’s air would be significantly cleaner without gas powered leafblowers.

  2. No wonder we have air pollution around George Town. All activity centers around George Town. When we have airplanes, cruise boats, cargo boats, the landfill dump and its frequent fires, the intense traffic… When will the government learn that they need to move industry away to other parts of the island. Are they going to act when reports come out saying the air around Seven Mile Beach and George Town is as bad the center of London – they will kill the golden goose as people will think twice if not three times before they think to spend so much money to have a condo on Seven Mile Beach and have poor air quality. The government relies on revenue from those who spend millions of dollars for these pricey condos. The people who have these funds are not 20 year olds but people in their 50’s, 60’s and older who will be concerned if they have any level of sensitivity to air quality. Wake up, government, deal with the issue and start moving the industry away – decentralize before it is too late.

    You are ignoring all this information that is coming from many different areas pointing to the same problem. You continue to want to expand the port to have even more and bigger cruise ships in George Town, have a bigger cargo port for more polluting boats and of course more cars and taxis to move the 20,000+ cruise visitors coming off these even bigger cruise ships in and around the Georgetown and Seven Mile Beach area.

    Please keep the citizens healthy for their future. They own this island and have elected you to manage it. You are managing the coronavirus well by making the hard choices. It is difficult for everybody but very rewarding for the future. Keep this future in mind and do the same by decentralizing George Town/Seven Mile Beach area. Show to the citizens how you plan to give them a long-term healthy island for them and their children.

  3. No one mentions vapor pressure which is a pesticide’s tendency to evaporate, change from a solid or liquid into a vapor. Some pesticides will stay grounded after they are applied, others may be more likely to move up into the air. It is important to know which type of pesticide you might be dealing with before it’s used.

    Pesticides with higher vapor pressures tend to move into the air faster and easier. Temperature plays a very large role here. In general, pesticides will have lower vapor pressures at lower temperatures. As temperature goes up, so does the pesticide’s vapor pressure.

    In the air, pesticides can break down, be breathed in, and move away from the treated area into new areas. When pesticides move off-target as vapors, that is known as vapor drift. Becoming a vapor isn’t the only way that a pesticide can move away from the place it is applied. Dust particles or spray droplets can also move through the air during or shortly after pesticide use. This is known as particle drift.

    Then, there are herbicides, mosquitocides…

    After a rain I have to stay inside until cocktail of herbicides, insecticides and all other “cides” clears from the air. I am extremely sensitive to “after-a-rain” odors which hit me really hard, I start choking and coughing.

  4. Landfill Gases!!! There is allot of data on this topic by the United States government. Go to this article:
    Put aside the landfill fires, our islands has a toxic dump in Georgetown!!! The prevailing winds pickup these toxins in the dust particles!!!
    The gases coming off this landfill needs to be capped off with a landfill liner, to contain and burn these gases off for electric power. This safe technology has been around for 40 years and our government has been blind to use it.

  5. As of 1/1/2020, all cruise ships were to follow the IMO’s 0.5% sulphur cap on marine fuels compared to the 3.5% they have used and still are using in many cases. Many countries have mandated the standard for any ship visiting their country; has Cayman? I doubt it. It must also be monitored, as many of the lines, especially those owned by Carnival, are notorious environmental rule-breakers.
    Dirty diesel fuel is not only used by cruise ships. Another source of pollution missed in the article is that generated by the power company that uses diesel for its generators. I am sure there are other diesel-powered generators being used on the island (water company?). What standards has our government imposed on them and what are the current import restrictions? A shift to solar power in the island should be a major government initiative.
    Hopefully, the current COVID-19 situation will result in more Caymanians becoming health- and safety-conscious for their children’s sake, if not for themselves.