According to a five-year survey conducted by the U.S. Environmental Protection Agency, indoor air pollution in many families is extremely high, which is several to dozens of times higher than outdoor air pollution. The China Health Education Association has also published a report that summer is a time of high incidence of allergies, and indoor air pollution is four to five times higher than outdoor air pollution. So, what factors lead to indoor air pollution in summer more serious than outdoor?

3月1日，我国实施的《室内空气质量标准》把室内生物性污染与化学性污染、放射性污染共同列为室内环境三大污染物质。

On March 1, the indoor air quality standard implemented in China listed indoor biological pollution, chemical pollution and radioactive pollution as the three major indoor environmental pollutants.

，夏季室内尤其要警惕化学性污染。生活中，常有人遇到这样的困惑：装修好几年了，污染还是没散尽，一到夏天就能闻到刺鼻的气味。建筑装饰协会住宅装饰装修委员会秘书长张仁告诉记者，来自装修和家具中的甲醛等化学性污染物释放周期较长，可达几年甚二三十年。夏季高温、潮湿，污染物的释放速度会加快，如果长期关闭门窗，污染物便无法有效扩散。长此以往，家人可能会头晕、恶心、咳嗽，甚呼吸困难。其次，潮湿高温的环境也增加了生物性污染的几率。

First of all, we should pay special attention to chemical pollution in summer. In life, people often encounter such a puzzle: after several years of decoration, the pollution is still not exhausted, and you can smell the pungent smell in summer. Zhang Ren, Secretary General of the Residential Decoration Committee of China Building Decoration Association, told reporters that the release cycle of formaldehyde and other chemical pollutants from decoration and furniture is long, up to several years or even 20 to 30 years. In summer, due to the high temperature and humidity, the release rate of pollutants will be accelerated. If the doors and windows are closed for a long time, the pollutants will not spread effectively. In the long run, family members may be dizzy, nauseous, coughing, and even breathing difficulties. Secondly, humid and hot environment also increases the probability of biological pollution.

加拿大一项调查表明，室内空气质量问题有21%是微生物污染造成的，主要包括细菌、真菌、花粉、病毒等，可能会引起过敏及哮喘等呼吸系统疾病。再次，各类家电加重了室内PM2.5污染。北京市疾病预防控制检测数据显示，在室内吸烟可使PM2.5数值翻12倍。如果有烹调等其他人为活动，还会使PM2.5浓度大增。张仁表示，夏季，室内空调、空气净化器等家电长时间开启，如未定期清洁，不仅会将颗粒物吸附在过滤网上，还可能使其扩散整个房间，加重污染。

According to a survey in Canada, 21% of indoor air quality problems are caused by microbial pollution, mainly including bacteria, fungi, pollen, viruses, etc., which may cause respiratory diseases such as allergies and asthma. Thirdly, all kinds of household appliances aggravate indoor PM2.5 pollution. According to the data from Beijing centers for Disease Control and prevention, indoor smoking can increase PM2.5 by 12 times. If there are cooking and other human activities, the PM2.5 concentration will increase greatly. Zhang Ren said that in summer, household appliances such as indoor air conditioning and air purifier will be opened for a long time. If they are not cleaned regularly, they will not only absorb the particles on the filter screen, but also spread them to the whole room, aggravating the pollution.