Houston Asphalt: Heat Trapping Sunscreen Toxins?

By Franklin Everett Shaw

December 23, 2025

The air hangs heavy in Houston, thick with humidity and the scent of… something else. That something else might just be the asphalt baking under the relentless Texas sun, releasing a cocktail of chemicals into the air we breathe. It’s a problem few are talking about, but one that demands our attention, especially if you live near a busy road, a parking lot, or even a freshly paved driveway.

Houston’s asphalt isn’t just any asphalt. It’s a specific blend, often sourced from local refineries processing heavy crude. This means it can contain higher concentrations of polycyclic aromatic hydrocarbons (PAHs), known carcinogens, and volatile organic compounds (VOCs), which contribute to smog and respiratory problems. The intense heat acts as a catalyst, accelerating the release of these toxins.

So, what exactly are we dealing with? Houston asphalt typically comprises aggregate (gravel, crushed stone) and bitumen, a sticky, black, highly viscous liquid or semi-solid form of petroleum. The bitumen is the culprit. It’s a complex mixture of hydrocarbons, including:

• PAHs: Benzo[a]pyrene, chrysene, benzo[a]anthracene – these are the big baddies, linked to various cancers.
• VOCs: Benzene, toluene, ethylbenzene, xylene (BTEX) – these contribute to ground-level ozone and can cause headaches, dizziness, and nausea.
• Sulfur compounds: Hydrogen sulfide, carbonyl sulfide – these contribute to the unpleasant odor and can irritate the respiratory system.

The problem is exacerbated by Houston’s unique climate. High temperatures increase the rate of volatilization, meaning more of these chemicals evaporate into the air. Rainfall can then wash these chemicals into the soil and waterways, contaminating our environment further.

But how do you know if you’re being exposed? Here’s a DIY guide for Houston residents:

1. The Sniff Test: A strong, petroleum-like odor, especially on hot days, is a red flag. This is a good first step, but not definitive.
2. Visual Inspection: Look for oily sheens on surfaces near asphalt, especially after rain. This indicates leaching.
3. Dust Analysis: Collect dust samples from surfaces near asphalt (window sills, outdoor furniture). Send them to a lab for PAH analysis. While this isn’t cheap (expect to pay $100-$300 per sample), it provides concrete data. EnviroLab Services in Houston offers this type of testing.
4. Air Quality Monitors: While expensive, personal air quality monitors can detect VOCs. Look for models that specifically measure BTEX compounds. TSI AirAssure is a reputable brand, though a significant investment.
5. Water Testing: If you suspect runoff from asphalt is contaminating your water source (unlikely with city water, but possible with well water), test for PAHs and VOCs. The City of Houston offers water testing services, but you’ll need to inquire about specific PAH and VOC testing.

Okay, you’ve identified a potential problem. What can you do about it?

• Limit Exposure: This is the most immediate and effective step. Avoid spending prolonged periods near asphalt on hot days. Keep windows closed and use air conditioning with a HEPA filter.
• Sealants: Applying a sealant to asphalt surfaces can significantly reduce emissions. Look for water-based acrylic sealants specifically designed for asphalt. Latex-ite Sand Mix is a popular choice available at most Houston hardware stores like Home Depot and Lowe’s. Reapply every 1-3 years.
• Vegetation: Planting trees and shrubs around asphalt surfaces can help absorb some of the pollutants. Native Texas plants like Live Oaks and Yaupon Hollies are good choices.
• Activated Carbon Filters: Use activated carbon filters in your home’s HVAC system to remove VOCs from the air. Replace them regularly.
• Address Runoff: Ensure proper drainage around asphalt surfaces to prevent runoff from contaminating soil and water. Consider installing a rain garden to filter runoff.
• Advocate for Change: Contact your local city council member and advocate for the use of more environmentally friendly paving materials, such as porous asphalt or recycled asphalt pavement (RAP).

One common mistake is assuming that all sealants are created equal. Many contain coal tar, which is worse than the asphalt itself in terms of PAH emissions. Always check the label and ensure the sealant is coal tar-free.

Another pitfall is neglecting maintenance. Sealants degrade over time, so regular reapplication is crucial. Also, remember that vegetation only helps to a certain extent. It’s not a substitute for other mitigation measures.

Let’s consider a real-world scenario: You live in a neighborhood near Hobby Airport in Houston, where increased air traffic has led to the expansion of parking lots. You notice a strong petroleum smell on hot days and are concerned about potential health effects.

1. Start with the sniff test and visual inspection.
2. If you suspect a problem, consider collecting dust samples for PAH analysis.
3. Apply a coal tar-free sealant to your driveway and any other asphalt surfaces on your property.
4. Plant trees and shrubs along your property line to help absorb pollutants.
5. Contact your city council member to express your concerns about air quality and advocate for the use of more environmentally friendly paving materials in future airport expansions.

This isn’t just about individual action. It’s about collective responsibility. By raising awareness and demanding change, we can create a healthier environment for all Houstonians. The Texas heat is here to stay, but the toxic legacy of our asphalt doesn’t have to be.