Indoor Air Testing Methods

After renovating a new house, many people choose to wait before moving in. This is because indoor air pollution can be harmful during the renovation process. Formaldehyde is one of the most dangerous pollutants, and it poses serious health risks. In this article, we will explore the methods and instruments used for indoor air testing. Let's take a closer look.

Indoor air testing is a scientific process that uses modern technology to measure and analyze harmful pollutants in the air, either continuously or at intervals. It helps assess the impact of these pollutants on human health. Studies show that individuals living in homes with better indoor air quality tend to live longer than those in poorly ventilated environments. This is why many families prioritize indoor air testing.

Indoor Air Testing Standards:

1. The living room should be closed for 12 hours following the National Indoor Air Quality Standard (GB/T18883-2002). Air conditioning and other devices should not be used during this time.

2. During on-site inspections, no more than three people should be present in the room.

3. Smoking is strictly prohibited when conducting indoor air tests.

4. All decorative debris, such as paint, thinners, and boards, must be removed before testing.

5. Avoid using deodorizing products indoors within one week before the test.

6. The detection time depends on the number of sampling points, usually taking about 1 hour for 2–3 points.

When accepting a construction project, the number of detection points should be set based on the room area:

1. If the room area is less than 50 m², one point is required.

2. For rooms between 50–100 m², two points are needed.

3. For rooms larger than 100 m², 3–5 points should be set.

Indoor Air Testing Equipment:

Formaldehyde is the primary pollutant tested in indoor air. Other harmful gases like benzene, ammonia, VOCs, and ozone are also monitored. Common testing equipment includes formaldehyde detectors, air samplers, particle counters, ammonia detectors, CO2/CO meters, and more.

Indoor Air Detection Methods:

1. Formaldehyde Detection: There are four standard methods—AHMT spectrophotometry, phenol reagent spectrophotometry, gas chromatography, and acetylacetone spectrophotometry. Each method involves different chemical reactions and quantification techniques.

2. Benzene, Toluene, and Xylene: These are typically detected using gas chromatography after being collected by activated carbon tubes and analyzed with a hydrogen flame ionization detector.

3. Ammonia Detection: Two main methods are used—indophenol blue spectrophotometry and Nessler reagent spectrophotometry, each suitable for different concentration ranges.

4. Total Volatile Organic Compounds (TVOC): Gas chromatography is used, where samples are collected and analyzed using a capillary column and a flame ionization detector.

5. Ozone Detection: Two methods exist—ultraviolet absorption and indigo disulfonate spectrophotometry, both measuring ozone levels through light absorption or color change.

6. Cockroach Detection: Methods include scintillation flat measurement, track etching, and double filter membrane technique. Some advanced tools like the MODEL1027 offer continuous monitoring.

Appendix

Beijing Zhongyi Yusheng Technology Co., Ltd.

Dedicated Gas Chromatograph Configuration for Indoor Environment (TVOC) Testing:

Equipment Name	Model and Specifications	Unit	Quantity
Gas Chromatograph	Host + FID + Filling system + Capillary system	Station	1
Chromatography Workstation	BF-2002 TVOC special edition dual channel	Station	1
Air Generator	0–3000 ml/min	Station	1
Hydrogen Generator	0–310 ml/min, 99.999%	Station	1
Nitrogen Bottle	High purity nitrogen, 99.999%, pressure reducing valve	Set	1
ATDS-6000 Thermal Analyzer	Analysis, activation, 6 branches	Station	1
Spectrophotometer	For formaldehyde and ammonia detection	Station	1
Measuring Instrument	FD216	Station	1
Dual Gas Path Sampler	QC series, 0.1–1.5 L/min	Station	1
QC-6H Constant Current Sampler	0.4–0.6 L/min	Station	1
BS-H2 Constant Flow Pump	100–500 ml/min	Station	1
Empty Box Pressure Gauge	DYM3	Station	1
Thermometer	TES1360	Station	1
Digital Blast Drying Oven	9030MBE	Station	1
Quartz Double Distilled Water Meter	SZ-93	Station	1
Electronic Balance	0.1 mg, 200 g	Station	1
Sample Box	With absorption tube and sampling tube, aluminum bracket	Pack	1
TVOC Special Column	US KB 0.32 mm × 50 m × 1 μm	Support	1
Benzene Special Column	3 mm × 2 m	Support	1
Tenax Adsorption Tube	200 mg, 50 per box	Box	1
Activated Carbon Sampling Tube	50 per package	Package	1
Bubble Absorber	10 ml (optional)	Support	1
Glass Plate Absorber	10 ml (optional)	Support	1
TVOC Standard Solution	10, 100, 1000 µg/ml	Set	1
Benzene Standard Solution	2 ml	Support	1
Benzene Standard Gas	2 L, 5 components	Bottle	1
Phenol Reagent	5 g	Bottle	1
Formaldehyde Solution	20 ml, 100 mg/L or 2 ml, 10.2 mg/ml	Support	1
Ammonia Solution	20 ml, 500 mg/L	Support	1