 Due to unregulated manufacturing of brick and other causes Dhaka is one of the most polluted world cities with very high levels of PM2.5 air pollution.There are many parks within Dhaka city, including Ramna Park, Suhrawardy Udyan, Shishu Park, National Botanical Garden, Baldha Garden, Chandrima Uddan, Gulshan Park and Dhaka Zoo.There are lakes within city, such as Crescent lake, Dhanmondi lake, Baridhara-Gulshan lake, Banani lake, Uttara lake and Hatirjheel-Begunbari lake.