Understanding VOCs in Urban Wildfires

Tracking pollutants from wildfires, like VOCs and particulates, can be challenging because of factors such as wind, temperature, the variety of materials burning, and limited monitoring resources. This primer, and these FAQs, are gathered with the intention of creating a starting point for education. The issues and concepts contained here are not easy to understand; when confronted, they are best tackled by teams, rather than individuals, and nobody should expect to hold all the answers. While specific data might not always be available, staying informed and cautious is essential for safety. We maintain that there is no evidence to indicate any kind of wide-scale conspiracy to hide data from the public, or mislead the public into a false sense of security by using AQI as an air quality metric. We are dealing with massively interconnected environmental systems that touch on aspects of physics, chemistry, biology, and mathematics that provide no easy answers.

What are VOCs, and how do they get released in urban wildfires?

Volatile Organic Compounds (VOCs) are gases released when materials like buildings, vehicles, and household items burn. In an urban wildfire, synthetic materials (e.g., plastics, electronics) can produce additional VOCs on top of those from natural sources like wood.

Reference

• US EPA,OAR Technical Overview of Volatile Organic Compounds | US EPA
• Dianna Smith Understanding TVOC: What You Need To Know About Volatile Organic Compounds
• Halley Myers Wildfires and the Wildland Urban Interface | Chemical Insights

What kinds of VOCs are usually found in the air during urban wildfires?

Common VOCs include toluene, benzene, and formaldehyde, all of which can be released by burning plastics, paints, or building materials, which are commonly found in urban fires. These pose a substantial risk on top of the smoke from the wildfires.

OK, so what are some other VOCs? Well, you asked:

References

• MDPI Impacts on Urban VOCs and PM2.5 during a Wildfire Episode

Why should we care about VOC levels during these fires? How do they affect our health and air quality?

VOCs can lead to health problems like respiratory irritation, eye irritation, headaches, and in higher concentrations, more serious complications. Children, older adults, and people with existing health conditions are often most vulnerable.

References

• Chantelle Lee Your Questions About Wildfire Smoke and Health, Answered
• US EPA,OAR Volatile Organic Compounds' Impact on Indoor Air Quality | US EPA
• PubMed Central (PMC) Health Risk Implications of Volatile Organic Compounds in Wildfire Smoke During the 2019 FIREX‐AQ Campaign and Beyond

How do VOC readings tie into the AQI? And why doesn’t AQI tell the whole story?

The Air Quality Index (AQI) primarily measures pollutants like particulate matter (PM2.5/PM10) and ozone. It doesn’t directly measure VOCs. Because of this gap, the AQI might underrepresent the total risk if VOCs are high.

The active word here is might. It’s incredibly difficult to detect VOCs reliably over distances. VOCs can contribute to ozone formation and indirectly affect AQI, which is one way to track their distribution, but that is not a precise indicator.

Don’t like that answer? Neither do we. This is why we want to see more attention paid to implementing better mechanisms for measurement around urban populations.

References

• www.sciencedirect.com

What tools are used to check VOC levels, and what makes it tricky to track them in cities?

There is a wide range of specialized commercial equipment used to detect and measure VOCs:

These devices face numerous challenges when deployed to detect VOCs in urban environments. The presence of other pollutants and varying environmental conditions can interfere with accurate readings, while the need for regular calibration adds to operational complexity. Interpreting the data requires significant expertise, and the high costs strain monitoring budgets.

Each device typically has limited detection ranges for specific compounds, meaning multiple types of sensors may be needed for comprehensive monitoring. Environmental factors like temperature and humidity can significantly affect sensor accuracy, and the requirements for consistent power supply and supporting infrastructure make deploying these tools in emergency situations particularly challenging, even when they are built for portability.

As a result, most cities have limited monitoring capabilities, often relying on a few fixed stations supplemented by mobile monitoring units during emergencies.

Consumer-level outdoor VOC detectors do exist (like from ATMO and PurpleAir), but they do not have the same degree of fidelity or accuracy as commercial devices. That said, they can be used for effective crowd-sourced VOC monitoring with some caveats.

Indoor VOC detectors like those sold by Awair, Airthings or Amazon are calibrated specifically to do the job they do: measure VOCs in a stable indoor environment. Taking them outside will likely result in odd readings; don’t expect them to self-calibrate to an outdoor environment.

References

• What VOCs Are and How They Affect You | Enviro-Equipment Inc
• www.sciencedirect.com

Why might VOCs not always be monitored or reported accurately?

Several factors complicate VOC monitoring and reporting during wildfire events.

Technical complexity arises from the hundreds of different VOCs present during fires, each requiring specific detection methods and potentially interfering with each other's measurements. Most monitoring stations focus only on basic pollutants, and the specialized equipment needed requires frequent calibration.

Environmental factors like temperature changes affect vapor pressure and detection accuracy, while humidity interferes with sensors. Wind patterns and urban pollution sources further complicate consistent measurement.

Practical constraints include the limited number of monitoring stations and their high maintenance costs. The need for specialized training, restricted real-time monitoring capabilities, and time-consuming laboratory analysis make comprehensive VOC tracking challenging.

References:

• Understanding Volatile Organic Compounds (VOCs) and TVOC Measurements

What can we do to protect ourselves from VOC exposure during urban wildfires?

Masks & Protection

• Use properly fitted N95 masks (minimum) for general wildfire smoke protection. For areas with potential VOC exposure, use P100 respirators with appropriate VOC filters (like 3M 60926 or 60923)
• Remember that casual mask wearing isn't enough - proper seal and fit testing are essential for wildfire smoke protection
• Wear tight-fitting safety goggles if ash is present in the air or when in/near burn zones

Home Protection

• Keep windows closed and disable any fresh air intake on your HVAC system
• Use MERV13+ filters in your HVAC system if compatible (check manual first - these can strain some systems)
• Place high-quality air purifiers with both HEPA and charcoal filters in main living areas
• Change HVAC filters more frequently during wildfire events (don't wait the usual 3 months)

Additional Safety Measures

• Monitor both AQI and VOC levels if you're near burn zones (AQI alone doesn't tell the full story)
• Limit outdoor activities when air quality is compromised
• Verify that carbon monoxide detectors are working properly
• Avoid activities that add to indoor air pollution (smoking, burning candles, using fireplaces)

When in doubt, follow official evacuation orders and guidance from local authorities. This is a simplified guide - please review the complete primer for detailed information and resources.

What crowd-sourced VOC initiatives are out there?

We are working with ATMO to build a local network of outdoor VOC detectors in Los Angeles, owned by private citizens, some of whom carry them around the city during their daily routines. This is not a unique concept, but we believe the more citizen science there is around the issue, the better. We will update the FAQ as we launch a public portal to track results.

PurpleAir provides a map that aggregates data from their own sensors.

Use this information at your own risk. Please consult with local agencies regarding laws and regulations. This information is provided without warranty or guarantee. Your safety comes first. Be careful, be empathetic, and please don’t be an asshole.