How to test toxic gases from building materials?

Smoke toxicity testing is a key method for evaluating the composition and concentration of toxic gases released during combustion or high-temperature decomposition. It is widely used in the construction, transportation, electronics, and other fields to ensure personal safety during fires. Building material toxic gas analysis tests for toxic gases released during combustion, assessing their safety in fires. This testing is crucial for fire safety in building materials, electronic and electrical products, and vehicle interiors. It helps companies and consumers understand potential product risks and ensures compliance with international and national safety standards. Scientific analysis of smoke toxicity can effectively prevent fire-related casualties and provide data support for product design improvements and regulatory development.

Related Standard: EN 13501-2 Smoke Toxicity Testing

In the field of building material fire safety, the EN 13501-2 standard is the core basis for assessing combustion smoke toxicity in the EU CE certification system. By scientifically quantifying smoke toxicity parameters, this standard provides a critical benchmark for evaluating building material safety in fires, directly impacting a product's access to the European market.

The EN 13501-2 standard divides smoke toxicity testing into three stages: first, simulating material combustion using equipment such as a tube furnace or cone calorimeter to collect the released smoke components; then, using gas chromatography/mass spectrometry, analyzing the concentrations of over 20 toxic gases, including CO, HCN, and HCl; and finally, calculating the FED (fractional effective dose) index according to the EN ISO 13571 standard. A passing grade is determined when the FED value is ≤1. The test focuses on the critical escape period of the first 10 minutes, which closely aligns with the prime time for evacuation in actual fires.

The current standard categorizes smoke toxicity into three levels, t0-t2. T0 is the most stringent, requiring an FED ≤ 0.4 and a toxic contribution of no more than 30% from a single gas. Notably, the 2023 revision adds restrictions for fluorinated compounds, reflecting the continuous improvement of the standard to accommodate the development of new building materials. Test specimens must simulate actual installation conditions, such as cables being tested with brackets and wall materials taking into account the impact of cavity structures. This "real-world" testing approach significantly improves assessment accuracy. Compared to the US ASTM E1678 standard, EN 13501-2 includes five additional gas analysis indicators and requires dynamic combustion testing rather than fixed-temperature testing. This discrepancy results in approximately 15% of building materials meeting US standards but failing European standards. China's GB/T 20285-2006 standard is closer to the EU system, but lacks testing requirements for organic acid gases.

Building material companies seeking CE certification must establish a comprehensive quality control chain, rigorously monitoring everything from the percentage of flame retardants added to raw materials to the combustion performance of finished products. A well-known insulation material manufacturer demonstrated a 62% reduction in HCl emissions, ultimately achieving T1 rating, by switching to an aluminum hydroxide flame retardant system. Currently, approximately 67% of Class A fire-resistant building materials in the EU market also meet T0 smoke toxicity requirements. These products typically carry the full "Euroclass A2-s1.t0" label.

With the increasing popularity of green building concepts, future standards may incorporate environmental toxicity indicators such as carbon dioxide equivalents. Exporters are advised to conduct pre-testing in advance, focusing on improvements to materials such as polyvinyl chloride and polyurethane that are prone to producing highly toxic smoke. If necessary, a comprehensive assessment can be conducted in conjunction with the EN 13823 single-unit combustion test. Understanding these technical requirements will not only ensure smooth certification but also provide true fire safety for building occupants.

Related Test Methods

1. Smoke Density Test

Smoke density testing assesses smoke density by measuring the light transmittance of smoke produced during combustion. This method provides quantitative data on the ability of smoke to obstruct vision. The test is typically conducted in a controlled environment. Building materials are heated until combustion occurs, and the resulting smoke passes through a measuring beam. The intensity of the beam changes proportionally to the density of the smoke, allowing the smoke density value to be calculated.

2. Toxicity Analytical Testing

Toxicity analytical testing focuses on the chemical composition and concentration of harmful substances in combustion products. This includes the detection of toxic gases such as carbon monoxide, hydrogen cyanide, and hydrogen chloride. These tests are typically conducted in a laboratory setting, using analytical instruments such as gas chromatography and mass spectrometry to identify and quantify toxic substances in combustion products.

3. Animal Exposure Testing

Animal exposure testing is a direct method for assessing the toxicity of combustion products. In this method, animals (usually mice or rats) are exposed to smoke produced by combustion, and their physiological reactions and survival are observed. This method can provide direct evidence of the effects of smoke on organisms, but is becoming less commonly used due to ethical and cost issues.

4. Cytotoxicity Testing

Cytotoxicity testing assesses the toxicity of combustion products by exposing them to cell samples. This method can evaluate the direct effects of combustion products on cell structure and function. Cytotoxicity testing is typically performed using cultured cells in vitro, and toxicity is assessed by observing changes in cell death, DNA damage, or other biomarkers.

5. Heat Release Rate Testing

The heat release rate test assesses the rate of heat release during the combustion of building materials. While this method does not directly measure smoke toxicity, it provides important information about the rate of combustion product production, which indirectly affects smoke toxicity. The test is typically conducted in a controlled environment, where the building materials are heated until they burn and the heat released is measured.

6. Oxygen Index Testing

The oxygen index test assesses the minimum oxygen concentration required for a material to burn. This method provides information on the combustion characteristics of a material, which indirectly affects smoke toxicity. The higher the oxygen index, the more difficult the material is to burn and the less toxic the smoke it may produce.

7. Combustion Product Analysis Testing

Combustion product analysis testing assesses smoke toxicity by analyzing the gases and particulate matter produced during combustion. This method provides detailed information on the composition of combustion products, including both toxic and non-hazardous substances. Test results can help understand the potential harmful substances produced during combustion and assess smoke toxicity.

As a critical component of fire safety, smoke toxicity testing is undergoing standardization and diversification, driving technological innovation in the global building materials industry. From the precise simulation of dynamic combustion scenarios in the EN 13501-2 standard, to the systematic development of testing methods such as smoke density and toxicity analysis, to the exploration and application of cutting-edge technologies such as cytotoxicity and animal exposure, a toxicity assessment system has been established that covers the entire material combustion process. In response to the growing trend toward green buildings and innovative materials, companies must establish comprehensive quality control from raw materials to finished products based on international standards, while also focusing on pre-research of environmental toxicity indicators and material improvements. Only by deeply integrating scientific testing with industrial practice can we strengthen the last line of defense for fire safety and provide more reliable life safety for the global building environment.