Packages for express delivery goods in China are expected to be thinner and more recyclable to reduce environmental stress, according to a new national standard.

The recommended standard, to take effect on Sept 1, is intended to reduce the harmful environmental effect caused by packaging waste with China's rapidly developing express delivery industry, according to China's Standardization Administration.

It is necessary to encourage enterprises to use environmentally friendly packages and adhesives that result in reduced pollution and emissions, and consume less energy to move parcels, the administration said.

The latest standard had been in use since 2009 and lacks enough environmental specifications for packages, the administration said.

Package bags made of plastic film should now be between 0.03 and 0.08 millimeters in thickness, according to the new standard, less than the current standard of between 0.06 mm and 0.08 mm.

Bags made of woven plastic fabric can now be a minimum of 70 grams per square meter, a reduction of 10 g.

The new standard also includes content limits for certain heavy metals and chemical compounds for packages such as lead, mercury and cadmium. For example, lead content should not exceed 100 mg per kilogram of package bags.

The standard also includes recommendations over the use of biodegradable plastics in producing package bags, and encourages the reuse of package boxes for delivery.

Express delivery companies delivered 40 billion parcels last year in China, an increase of 28 percent over the previous year, ranking top globally for the fourth consecutive year, according to the State Post Bureau.

In 2016, 6.8 billion plastic bags and 330 million rolls of tape were used for express delivery in China, according to a report released by the bureau.

Less than 20 percent of package bags in China are recycled, and almost all tape is simply abandoned, Zhu Lei, a researcher in green packaging at Beijing Institute of Graphic Communication, told Workers' Daily.

Packages that are produced using biodegradable materials will account for half of all packages used for express delivery, and a special recycling system for express delivery packages will be established by 2020, according to a guideline released by 10 ministries and central government departments last year to promote green packaging in express delivery.