Definitely Doug 6/21/24: What’s That Smell?

by Doug Rice

If you read almost any ranking of common hotel complaints, you are likely to find two issues near the top of the list: cleanliness and noise. Within the cleanliness category, smoking odors are one of the biggest sources, so much so that they are often listed as a category of their own.

Smoking and noise complaints have always been issues for hotels. But it might surprise you to learn that while noise problems are generally stable, smoking has grown rapidly in recent years, due to growth in marijuana use and vaping.

According to the most recent data I could find, Gallup reports that only 11% of Americans smoked cigarettes in the past week, while 16% smoke marijuana regularly, and 8% vape (other substances, such as meth and fentanyl, were not surveyed). And while cigarette smoking has been in a long-term decline, marijuana smoking and vaping are increasing. A decade ago, only a few states permitted marijuana use. But by the time those Gallup polls were conducted in 2022, 19 states had legalized recreational marijuana. Today that total is 24 states, and likely to continue growing. As it does, the number of people who smoke it will surely continue to increase.

This week I will explore technology solutions that have recently come on to the market to address these issues for hotels. These are sensors that detect, report, and document anomalies, such as smoking and noise, that can lead to guest complaints. The products also provide documentation that can be used to fight chargebacks related to smoking fees that many hotels assess when they detect guest-room smoking.

I am as always indebted to those who generously shared their expertise on best practices, specifically senior executives from Alertify, FreshAir Smoking Sensors, Rest, and WYND. Rest was formerly known as NoiseAware, with a recent rebranding reflecting its change in focus from noise detection (primarily for short-term rentals) to smoking and noise detection for any type of lodging establishment. All these solutions address smoking, while some address noise, air quality, and other issues. All are specifically designed to meet the needs of hotels. Two other companies that sell similar solutions to hotels did not respond to requests for an interview.

I should note that there are various residential-grade devices that may sound similar. Some of them may meet the needs of casual accommodation providers such as bed and breakfasts and short-term rentals. But they typically lack the network monitoring and other features that hotels need, and they should be avoided unless (a) the only objective is deterrence, and (b) the units have audible alarms that can deliver that deterrence.

How Common is Guest-Room Smoking, and What Does It Cost?

Smoking incidents are much more common than most hotels think; what can be caught without detectors is just the tip of the iceberg. Many of the vendors collect historical data from hotels from before installation, so that they can compare the frequency of incidents detected before and after. One estimated that only about one in eight smoking incidents is detected and reported by housekeeping in the absence of detectors. And unless guests carelessly leave smoking materials visible to housekeepers and hotel security is called to obtain photographic evidence, it can be very difficult to prove that a particular guest was responsible – and hard to win credit card chargebacks of smoking fees.

While statistics vary by type of hotel, several of the vendors provided estimates that translated to smoking incidents in around 0.6% to 1% of occupied room nights, with some types of hotels as high as 2%. Even at the lower figure, that’s about one incident per day in a 200-room hotel.

Smoking in guest rooms is costly. FreshAir Sensor provided me with a copy of a very detailed study that tried to address the total costs per incident, including damage to property, cleanup costs, lost direct revenue, and lost business due to bad reviews (the biggest factor). Total costs per smoking incident were around $1,157, offset by an average of $145 collected in cleaning fees (by hotels that assessed one and were successful at collecting it). Luxury hotels’ costs were highest ($1,570), but their cleaning fees were also much higher ($594).

Others had less-formal estimates that were a bit lower, but they were primarily based on cleaning costs and lost revenue from having to take rooms out of service (no reputational impact). However it was measured, there was broad agreement that smoking incidents cost hotels a minimum of a few hundred dollars each, and often much more.

While smoking detection is generally the high-ROI application in hotels (because many hotels assess cleaning fees and these devices both increase the number of chargeable incidents and make it harder for guests to successfully challenge them), some of the products also address other issues related to guest satisfaction:

• Some can detect excessive noise from loud guests, nightclubs operating past hours, or even gunshots. Some hotels may find this useful, while others may worry that guests will be fearful their conversations are being recorded (although none of these solutions do this; rather they simply measure and record the decibel noise level).

• Some can detect air quality metrics, including the components of the Air Quality Index. Historically this has not been a priority for hotels due to a low perceived ROI, but this is starting to change as more and more travel management companies, meeting planners, and online travel agencies are now incorporating environmental and sustainability metrics in their listings and hotel ranking algorithms.

• Some can detect temperature, humidity, and mold (or mold risk). These can help to highlight issues with heating, ventilation, and air conditioning systems before they cause guest complaints or damage to the room.

Considerations for Evaluating Solutions

Every one of these solutions is probably a good choice for some hotels, but suboptimal for others. While my regular readers know that I try not to favor any specific product in these columns, in most cases my research nevertheless leaves me with biases that would apply if I were buying for my own hotel. That is not the case with this category. Which product I would favor would depend on the specifics of the hotel, including its clientele, size, management style, operational practices and even the design of the rooms.

Here are some of the key things to consider.

What are your goals? Discussions with the vendors highlighted products that were targeted at different objectives hotels may have. Some hotels just want to prevent smoking, while others are more focused on collecting incremental revenue from smoking fees. Most hotels would agree with the objective of reducing guest complaints. And while most hotels look at smoking detection as most valuable, some can also benefit from noise detection and other metrics. Finally, do you need a solution that can manage multiple properties from one dashboard?

Mounting location. The guest-room sensors need power, and depending on the model may be mountable on top of an outlet (dedicated or shared, depending on design) or may have a power cord. You need to locate them somewhere with good air circulation (don’t hide them in a cabinet) and accessible to an outlet that the guest is unlikely to find or to want to use. Depending on your objectives and the design of the device and its tamper-proofing properties, you may want the device itself to be mounted in an inconspicuous location such as the back of the television, or you may prefer a visible unit to discourage guests from smoking.

Tamper-proofing. Every solution I reviewed had features to frustrate tampering by guests, but some approaches may work better for you. One approach has LED lights that are normally on, but which turn off if the guest disconnects it from power to avoid detection. A battery backup keeps the unit active for at least several hours, however, alerting the hotel if the guest proceeds to smoke. Some solutions used a secure mount with a special key that makes the sensors impossible to remove from an outlet short of breaking them. Others rely on mounting in an obscure location, for example attaching to the back of a television, so that they are likely to remain undetected. Solutions need to report if a unit loses power; this might be via an alert to hotel management (useful if you want to catch a guest in the act), or only visible on a dashboard that would need to be checked regularly by hotel staff.

Accuracy. There are two common approaches to detecting smoke. One (pollutant density) basically measures pollutants in the air, and if they exceed a certain threshold, will trigger an alert, or further analysis that may result in one. Typically, these systems detect patterns of pollutant intensity (commonly particulates and volatile organic compounds) over time. They use the captured data to differentiate sources (tobacco, marijuana, vape, etc.) because each has characteristic signature elements (peaks, speed of dissipation, etc.). The sensors in this type of unit cannot distinguish tobacco from marijuana or vape; that comes from the analytics (in some cases AI-enhanced and self-adapting) of the density patterns over time.

The other approach is based on chemical detection of specific molecules found in tobacco, marijuana, vape, or other pollutants. This technology can distinguish one type of smoke from another. It is potentially less likely to generate false positives from permitted activities such as cooking, use of aerosol cleaners, incense burning, or even wildfire smoke, because the target molecules are present only in one source (for example, nicotine for tobacco). Sensors on these devices will need to be replaced periodically, although good ones should last at least a year and not be materially affected by the number of alerts triggered.

False positives matter, as one New York hotel found out when it was called out on the local news recently. And while my understanding of the underlying technologies could enable me to guess how different products might rank in terms of generating false positives, the truth is that there is no good data. The vendors all claim to have low rates of false positives, but one admitted that the only way to really know which is lowest would be to do side-by-side tests (put competing units in a room and then try out activities that might trigger them). Short of that, I would at least be sure to speak to several hotels using any product and explore both the metrics (number of smoking fees assessed and chargeback success rates). I would also analyze those hotels’ online reviews for insights (are too many guests complaining about fees charged when they say they did not smoke?).

Also be aware that some common housekeeping aerosol cleaners (notably ones with ammonia), and even some personal beauty products, can trigger some types of sensors. And while you cannot test every type of hair spray a guest might bring, you can and should at least test the housekeeping cleaners your hotel uses.

Vape detection is a special case. Because vape dissipates faster and generally leaves less of a lingering smell, it can be harder to identify. At the same time, it generally leaves less odor, causes less damage, and is less likely to generate complaints from subsequent guests, so many hotels are less concerned about it. Chemical detection looks for specific molecules commonly found in vape that are not present in tobacco or marijuana; it may be more reliable if vaping detection is important.

Customization. Be sure the product offers a dashboard and the ability to customize the sensitivity and available features of each sensor. This may include sensitivity levels (particularly for noise) or hours of operation (for example, when detecting noise levels in rooms near a nightclub, or to avoid cleaning aerosols from setting off a detector during housecleaning). For cost reasons, you may also choose to activate features like noise detection or humidity alerts only for certain rooms where they are needed.

Incident Reports. Be sure to closely evaluate the vendor’s incident reports. The first question is who is notified at the hotel when an incident is detected, and how. Different products support one or more of SMS, email, and popups on the front desk system, and may limit notifications to one person or allow multiple destinations. Immediate incident reports give the hotel the ability to (for example) send security to the room and collect photographic or other evidence while it is still available. Some hotels also choose to notify the guest by email or SMS, if only to remind them that a smoking fee has now been added to their bill.

But a bigger difference among systems is in the content of incident reports that can be used to dispute credit-card chargebacks of smoking fees. These can be notoriously difficult for hotels to win unless they can provide strong evidence of the infraction, and in most cases the incident report is what fills that role. It should include enough information so as to be difficult for the credit card company to refute: it should identify the room, the guest name, the date, the time, and the specific evidence (pollutant graphs, molecules detected, etc.). Some also include a good scientific explanation of why the evidence should be considered conclusive. Be sure to review various incident reports from any products you are considering, and to ask if they have been tested in any court cases.

Noise Detection.
For most hotels, noise will be a secondary issue, or one they do not think is worth addressing. But where it is important, critical considerations include the ability to set both noise thresholds and monitoring hours by sensor. Placement of the unit can matter as well: if it is too close to the television speaker, then the noise threshold for an alert might need to be set too high to catch other noise sources.

Operational Issues. While the idea of adding smoking detectors sounds simple, there are quite a few operational considerations that need to be thought through. The best solution to some of them may depend on the product selected. These include:

• Who should receive incident alerts, and how should they handle each type of incident?

• How will incident reports be reviewed and guests charged for violations? This may be a manual process, an automated process through a Property Management System (PMS) interface, or a hybrid (e.g. management reviews a list and decides who to charge).

• Should some or all guests be automatically charged when a violation is detected? If so, you will need a PMS interface. Some systems also allow the hotel to exempt certain high-value guests (casino high-rollers, top corporate accounts, etc.) if desired.

• Does the system report when a device is offline? How are the appropriate staff notified and how can management track resolution of the issue?

• If you will be charging a fee for violations, how much, and how will you disclose this? Will it vary by room type (e.g., higher for suites)? Should you put signage in guest rooms to warn guests?
• Are your credit-card authorization holds consistent with the smoking fees?

• How should front-desk agents be trained to deal with irate guests challenging a smoking fee?

• Should housekeeping checklists be updated to check the status of detectors? This can be particularly important if there is any likelihood of guests unplugging them and the hotel not detecting that from alerts or reports.

• When smoking is detected in a room, what is your threshold for remediation? A few puffs on a cigarette while leaning out a window may not merit deep cleaning, whereas an all-evening bong party with several potheads almost certainly will. You might rely on intensity and duration data from the incident report, or identify a few staff members with particularly sensitive noses to serve as your “canary in the coal mine” to detect smells that similarly sensitive future guests might notice.

A final consideration with respect to these operational issues is the extent to which the vendor helps you identify and address them (and whether you want or need that help). Vendors should also monitor your use of the system and alert you if you are not using it as effectively as possible – something that can easily happen through staff turnover.

Installation. Some vendors provide complete turnkey installation, while other systems are self-installed with varying levels of vendor support. For self-installation, look for a vendor that preconfigures each device to connect to your Wi-Fi, and labels them by room number. Look carefully at the electrical requirements and connection options, as well as form factors. Validate the preferred installation location for each room layout (see considerations above for accuracy and tamper-proofing).

Maintenance. Make sure that devices can auto-reconnect to Wi-Fi after a power or network outage. Understand whether and when any components need to be replaced periodically, and the cost of both the components and labor. Some products (although none of the ones mentioned here) reportedly require cartridge replacements as often as every three months or when triggered; this could represent a major cost, especially in a union hotel.

Pricing Models. Most of the vendors offered some flexibility, reflecting the relative newness of these products in the market. While customary device and software-as-a-service (SaaS) fees are common, some vendors offer the option to pay only a percentage of collected smoking fee revenues, and this may be useful especially if a hotel is uncertain how many smoking incidents it may experience. And of course, in considering the total cost of ownership, be sure to include installation and maintenance cost (whether from the vendor or internal) as well as warranty periods.


If your hotel is currently charging a smoking fee or is considering one, smoking sensors can provide a strong ROI, by identifying and documenting the significant number of smoking incidents that are likely undetected today. If you are unsure if you will have enough such incidents, most of the vendors can help you quantify it with minimal financial risk. And if you have noise issues, the noise detection capabilities can also be useful, even if deployed only to select rooms.

Douglas Rice

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