Tianlan's Viewpoint | How to judge whether the air quality in the house is good or bad? There is a new basis~

Author: Wang Qiuyi, Analyst at the Center for Clean Air in Asia

Did you know that indoor air is not the "air pollution refuge" you think it is? Indoor air pollutants are of various types and their sources are complex. And because we spend a lot of time indoors (especially in winter and during the epidemic), the health hazards caused by indoor air pollution should be taken more seriously.

But think positively: we may have more control over our indoor environment. So why not do more in the areas you can control? The first key step is to understand the problem and be able to determine the extent of the problem.

Through this article, you can add the following practical "Blue" knowledge points:

1. What are the types and causes of indoor air pollutants?

2. Why is it necessary to formulate and revise the "Indoor Air Quality Standard"?

3. What important changes have occurred in the new standard?

∞Outdoor influences indoor

Outdoor air pollutants such as particulate matter and ozone can enter indoor areas through ventilation and natural air flow, causing indoor air pollution.

Although the changes in indoor and outdoor air quality are not completely synchronized due to different ventilation and convection conditions, the indoor and outdoor pollutant concentrations are correlated , and more than 75% of the daily changes in indoor pollutant concentrations can be explained by changes in outdoor pollutant concentrations.

Outdoor air pollution affects indoor air quality in many ways. Open windows for ventilation, artificial ventilation facilities, and gaps in walls and windows can all allow outdoor pollution to "take advantage of the situation." A study using a model to predict indoor PM2.5 concentrations in 90 residential buildings in Beijing found that regardless of outdoor weather and window opening conditions, outdoor PM2.5 contributed 54% to 96% to indoor PM2.5 concentrations.

∞Indoor environment and human factors

Indoor decoration materials and common cleaning agents may release pollutants such as formaldehyde, VOCs (volatile organic compounds), and radioactive substances . Carbon dioxide emitted by human activities and mold produced in humid environments may become indoor air pollutants. In addition, for the vast majority of developing countries, especially residents in rural areas, indoor burning of solid fuels for lighting, heating, and cooking will also produce pollutants such as particulate matter, carbon monoxide, and polycyclic aromatic hydrocarbons.

What are the health hazards?

Many studies have shown that indoor air pollutants are very harmful to human health . The World Health Organization has detailed the potential risks of various indoor pollutants to human health in three indoor air quality guidelines. For example, VOCs and formaldehyde released from newly painted surfaces are associated with aggravated asthma. Indoor humid environments can affect respiratory health, including asthma, respiratory infections, and breathing difficulties. Indoor exposure to nitrogen dioxide will increase susceptibility to respiratory infections.

As production and lifestyles become more modernized, more of people's work and leisure activities can be done indoors.

A two-year study of nearly 10,000 participants conducted by Lawrence Berkeley National Laboratory found that people spend about 87% of their time each day in indoor environments such as homes or buildings .

The impact of indoor air quality on people's lives, work and public health cannot be ignored, and the formulation of relevant standards is also very necessary.

∞What is the international standard?

◉ Considering the impact of indoor air pollutants on human health, WHO has successively issued three indoor air quality guidelines, targeting moisture and mold; selected pollutants such as carbon monoxide, formaldehyde, naphthalene, nitrogen dioxide, polycyclic aromatic hydrocarbons, radon, trichloroethylene and tetrachloroethylene; and household fuel combustion.

◉The guidance values ​​for PM10, PM2.5, carbon monoxide, sulfur dioxide and nitrogen dioxide are also included in the WHO's Global Air Quality Guidelines.

◉The latest 2021 WHO Global Air Quality Guidelines apply to both indoor and outdoor environments, but exclude occupational work environments due to the specificity of the relevant exposure and risk reduction policies, and potential differences in population susceptibility between the adult workforce and the general population.

◉The 2021 edition of the Global Air Quality Guidelines has updated the guideline values ​​for some pollutants. Among them, the 24-hour average limits for common indoor air pollutants PM2.5 and PM10 are tightened compared with previous versions.

∞What is the standard in our country?

In 2002, the former Ministry of Health and the State Environmental Protection Administration jointly drafted the "Indoor Air Quality Standard" (GB/T 18883-2002), which came into effect in 2003.

In the past twenty years, my country's indoor living environment and types of indoor pollutants have undergone tremendous changes, and indoor air monitoring and analysis technology has also made new progress. At the same time, more domestic and foreign studies have further confirmed the adverse effects of indoor air pollution on human health. International organizations and countries around the world have also successively carried out the formulation and revision of indoor and outdoor air quality standards. Among them, the air quality guideline values ​​revised by the World Health Organization in 2021 mentioned above are also applicable to indoor environments.

Therefore, timely updating of my country's indoor air quality standards can provide a scientific basis for the evaluation of my country's indoor air quality and its health impacts, and is of great significance to improving indoor air quality and protecting people's health.

On July 11, 2022, the State Administration for Market Regulation and the National Standardization Administration jointly announced the release of GB/T 18883-2022 "Indoor Air Quality Standard", which will be implemented on February 1, 2023. This is the first revision of GB/T 18883-2002 "Indoor Air Quality Standard" in its 20 years of operation.

∞Four types of indicators

The new version of "Indoor Air Quality Standard" includes four types of indicators: physical, chemical, biological and radioactive, with a total of 22 items.

∞New

Among them, three chemical indicators, including trichloroethylene, tetrachloroethylene and fine particulate matter (PM2.5), are newly added items. The main considerations for this indicator addition include three dimensions: first , the pollutants have a clear indoor source; second , the evidence of health hazards is conclusive and has attracted the attention of international authoritative organizations; third , the pollutants pose certain health risks in China.

∞ Tightened

At the same time, the new version of the "Indoor Air Quality Standard" has tightened the requirements for five chemical indicators (nitrogen dioxide, carbon dioxide, formaldehyde, benzene, and inhalable particulate matter), one biological indicator (total bacteria count), and one radioactive indicator (radon). In addition, some indicator names and pollutant measurement methods have also been adjusted based on scientificity and feasibility.

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